Wednesday, October 20, 2021

Genetic Engineering of Solanum tuberosum L. to Enhance Resistance Against Abiotic Stresses: A Review - Juniper Publishers

 JOJ Sciences - Juniper Publishers

Abstract

Potato (Solanum tuberosum L.) today is the fifth most significant crop worldwide after wheat, maize, rice and sugar cane. Conventionally intogressing agronomic traits in potato is considered laborious and time consuming task because of sexuality barriers between wild and cultivated potatoes. However, potato has gone through genetic manipulations with the advent of genetic engineering technologies. These technologies have helped the researchers to introduce traits of economic importance. Several studies for abiotic (i.e. drought, chilling, heat, salt) tolerances and improvement in nutrient quality have been documented. Modern day technologies have emerged as a necessary tool in potato breeding programs, strengthening classical strategies to improve yield and yield contributing factors. The present review article describes the genetic improvements in potato by scientists worldwide utilizing modern biotechnological approaches to enahnce abiotic tolerance in crop along with the future prospects of the transgenic potato.

Keywords: Genetic improvements; Abiotic stress; GMOs

Abbreviations: GNP: Gross National Agricultural Product; BV: Biological Value; IPM: Integrated Pest Management; ABA: Abscisic Acid; bZIP: Basic Leucine Zipper; TF: Transcription Factor; CE: GC-rich Coupling Elements; ABRE: ABA-responsive Element; CBP80: Cap-Binding Protein 80; ROS: Reactive Oxygen Species; BADH: Betaine Aldehyde Dehydrogenase; COD: Choline Oxidase; NT: Non-transgenic; TPS1: Trehalose-6-phosphate Synthase; amiRNAs: Artificial MicroRNAs; DREB; Dehydration-responsive Element-binding, DRE/CRT: Dehydration-responsive Element/C-repeat; EMSA: Electrophoretic Mobility Shift Assay; P5CS: 𝛿1-pyrroline-5-carboxylate Synthetase; CDPKs: Calcium-dependent Protein Kinases; GalUR: D-Galacturonic Acid Reductase; desA: Acyl-lipid 12-desaturase; SCOF-1: Soybean Cold Inducible Zinc Finger Transcription Factor; sHsps: Small Heat Shock Proteins; ATP: Adenosine Triphosphate; CuZnSOD: Copper–zinc Superoxide Dismutase; APX: Ascorbate Peroxidase; NDPK2: Plant Nucleoside Diphosphate Kinase 2; SSA: Transgenics with CuZnSOD genes and APX transgenes only; SN: Transgenics with NDPK2 only; 2-Cys Prx : 2-cysteine peroxiredoxin; MV: Methyl Viologen; DHN4: Dehydrin 4; miRNA: Micro RNA; CRISPR: Clustered Regularly Interspaced Short Palindromic Repeats; Cas9: CRISPR-associated protein9 nuclease

Introduction

Potato is a family of the Solanaceae, an enormous plant family with more than 3000 varieties [1]. More than 374,463,885 million tones of potatoes are produced worldwide [2]. As the global population reaches to 9.7 billion by 2050, the potato will play important role in securing global food resources. In Turkey, potato accounts for 3% of the gross national agricultural product (GNP), whereas it is about 3.1% in the EU-27 countries, hence contributing significantly to Turkish economy. It was cultivated on an area of 172,000 ha with the production of 3.9 million tons of potatoes. Central Anatolia including Nigde shares more than 60% potato production in this regard [3]. Potato has high amount of protein after soybean; patatin is the dominant storage protein [4]. The tubers of potato contain important dietary origin of starch, protein, vitamins and antioxidants [5]. Potato protein contains great biological value (BV) with a BV of 90-100 in contrast with whole egg (100) [6].

Potato crop is exposed to various sorts of abiotic stresses including drought saline cold and heat stresses. In areas where there is erratic rain fall or inadequate water supply, the cultivation of potato remains challenging [7]. As the world is going to face global warming issues, water restriction would be a threat in coming decades [8,9]. Drought stress periods may vary yearly in terms of duration and severity [10]. As per Hijmans [11], the potato losses due to climate change are expected to be 18-32% in first quarter of this century. Therefore, the development of transgenic drought resistant potatoes is an important issue. Potato as a frost-sensitive species adopts cool environment, and its regular growth and improvement are prevented by high temperature. When the temperature increases above 25 °C, tuber’s growth is terminated, and when the temperature rises to 39 °C, growth of stems and leaves are terminated [12]. Therefore, efforts are going on to develop abiotic stress tolerant potatoes. The potato presents unique challenges and advantages to plant breeders. As it is propagated vegetatively by tuber cuttings, potato cultivars don’t need to be bred to produce homogenous plants from true seed. A major disadvantage of potatoes for breeders is that potato is tetraploid, making it difficult to transfer desirable traits between cultivars and to have them expressed in subsequent progeny. The several species of Solanum are cultivated in Peru and Central America. These species provide a rich source for potential traits to breed into S. tuberosum, including tuber qualities (e.g. colors ranging from white to deep purple skin and flesh) and resistance to insect pests and diseases. Unfortunately, many of these wild Solanum relatives are diploid that further complicates breeding process. Hence, insertion of candidate gene(s) encoding for desirable economic trait by genetic engineering is a particularly attractive and valuable process for developing new potato cultivars [13]. There are many success reports of development of transgenic crops with traits of tolerance to abiotic stress [14]. These transgenic plants are becoming important components of integrated pest management (IPM) worldwide [15].

Improvement of Drought Stress Tolerance in Potatoes

S. tuberosum L. has been reported to be extremely sensitive to the drought stress, and with its leaves being more sensitive as this plant has less capability to absorb water from soil as compared to other crops [16]. The shallow root architectural system in potatoes is particularly detrimental to potatoes in that under drought, increased salinity and extreme temperature fluctuations, tuber yield and quality can be significantly plummeted [16-19]. Drought alone is expected to significantly decrease potato yield as much as 18 to 32% over the period of 2040-2069 [11]. Drought stress can bring about reduction in photosynthetic rate as well as reduction on biomass fresh weights of potato leaves and also it affects leaf number, leaf size and shoot length [16-18, 20-22]. One of the strategies that have been employed in ameliorating drought tolerance has been by introducing transgene that codes for bZIP (basic leucine zipper) TFs (transcription factors). On ABA (Abscisic acid) signal perception by specific receptors, signal transduction takes place when phosphorylation of bZIP TFs takes place via Ser/ Thr kinases which activate these bZIP TFs to bind to CE (GC-rich coupling elements) or cis-acting ABRE (ABA-responsive element) sequences to elicit various abiotic stresses [23]. Moon et al. [24] reported that the CaBZ1 gene isolated from hot pepper (Capsicum annuum) that encodes for bZIP transcription factor induced by ABA and under salinity and osmotic stresses when over-expressed in potatoes didn’t result in detrimental phenotypic traits in transgenic potatoes.

Under ABA treatment and drought condition, the transgenic plants showed a prompt stomatal closure with a decline in water loss rate and elevated yield under drought stress as compared to the wild-type. Kim et al. [25] generated improved drought tolerant transgenic potatoes based on decrease in water loss by overexpressing AtYUC6 gene associated with auxin biosynthesis in potato under CaMV 35S promoter using pCAMBIA1300pt–YUC6 construct. The transformed plants exhibited phenotypes associated with high-auxin like increment in the heights, erect stature, longevity and narrow-downward curled leaves. Pieczynski et al. [26] silenced the cap-binding protein 80 (CBP80) gene in potato cultivar Desiree using artificial miRNAs. CBP80 protein regulates miR159, MYB33 and MYB101 levels which are known to be the important regulators of ABA transduction pathway and drought tolerance. Downregulation of CBP80 was observed in silenced potato plants with decreased miR159 levels and increased levels of its target mRNAs, MYB33 and MYB101, which rendered higher drought tolerance in silenced plants. In addition, ABA-hypersensitive stomatal closing, elevation in thrichome and leaf stomata densities with decrease in number of michrochannels were reported, which correlated with increased tolerance to water stress. Similar pattern was reported in cbp80 mutant Arabidopsis. One of the major osmolytes, glycine betaine, accrues when encountered by abiotic stresses such as drought, high salinity and extreme temperature conditions. Not all plant species are capable of natural production or accretion of glycine beta. There has been extensive research with the ability to generate this compound in transgenics to ameliorate its tolerance to salt, cold, drought or high temperature stresses. Choline monoxygenase catalyzes conversion of choline to betaine aldehyde and ultimately to glycine beta under the catalysis of betaine aldehyde dehydrogenase [27-29]. Cheng et al. [30] cloned codA gene, obtained from Arthrobacter globiformis that directly converts choline to glycine beta, under the SWPA2 promoter to generate transgenic potatoes. The water stress was simulated with 20% PEG under the control of SWPA2 promoter. Accumulated glycine beta was reported in transgenic potatoes while non-transgenic potatoes exhibited no glycine beta accumulation as potato is not a glycine beta accumulating plant. Furthermore, reactive oxygen species (ROS) was shown to be accumulated and the transgenic potatoes exhibited strong drought resistance and recover ability. They further demonstrated that the glycine beta produced as a result of codA gene expression in transgenics could prevent membrane lipid peroxidation and degradation of chlorophyll caused by stress. Zhang et al. [31] reported that the cloning of transgene BADH gene (Betaine aldehyde dehydrogenase), under the control of drought- and NaCl- induced promoter rd29A from A. thaliana, into potato cultivar Gannongshu 2 increased the plant height of transgenic potatoes under NaCl and PEG stresses by 0.4 to 0.9cm, whereas fresh weight per plant increased from 17-29% as compared to non-transgenic controls indicating the drought and salt tolerances enhanced in the transgenics when BADH activity was upregulated.

Choline can be directly catalyzed to GB by choline oxidase (Cod) but it does not exist in higher plants. Different sources were adopted to transform codA gene: one by taking the gene from rhizobacterium and using promoter SWPA2 from sweet potato [32], and the other from transit peptide of Rubisco from tobacco [33]. The transgenic plants showed better tolerance to drought and salinity stress as compared to non-transgenic (NT) ones. There was also improvement in biomass of potted transgenic plants as compared to NTs when they were kept in water less conditions for 14 days to observe drought tolerance. Cheng et al. [30] further proceeded with these experiments by focusing on antioxidant system in drought conditions. The plants were kept in drought stress for 4 days and later were subject to rehydration conditions for 2 days. Transgenic plants were better to non-transgenic ones in many aspects including higher chlorophyll content, higher activity of antioxidant enzymes (caralase, peroxidases and superoxide dismutase), lower MDA and better recovery from water deficiency. Thus, tolerance against drought stress can be controlled in potato plants by increasing accumulation of GB. One of the elements involved in ROS signaling pathway in Arabidopsis is Arabidopsis annexin 1 (AtANN1). A family of calcium and membrane binding proteins, annexin, has also been found to confer stress tolerance to plants. ROS triggers boost in Ca2+ under salinity stress conditions and AtANN1 has been thought to be involved in activation of calcium conductance by NADPH oxidases in root epidermal cells. Annexin’s major role is to offset oxidative stress to maintain cell redox homeostasis and ameliorate tolerance against drought stress [34, 35]. Szalonek et al. [35] studied the role of StANN1 by overexpressing StANN1 in potatoes under CaMV 35S promoter and obtained more drought tolerant transgenics than the wild type with more water in green tissues, maintained chloroplast function with chlorophyll b and xanthophylls accretion. Also, the study inferred that the transgenic potatoes maintained effective photosynthesis during drought stress that increased its yield rate than non-transformed plants even under water stress. Trehalose overexpression has been shown to confer resistance against abiotic stress in plants such as rice and Arabidopsis [36-38]. However, in potatoes, it has been reported to be challenging to develop drought resistance transformants [39]. Nevertheless, improved drought tolerance in potatoes has been reported. Stiller et al. [40] cloned trehalose-6-phosphate synthase (TPS1) gene isolated from yeast with StDS2 drought inducible promoter and transformed the construct in White Lady potato cultivar. The resulting transgenics were drought tolerant and displayed higher stomatal conductance with increased net photosynthesis rates as compared to the wild types. There has also been a report on the use of artificial microRNAs (amiRNAs) in silencing CBP80/ABH1 gene in S. tuberosum to increase tolerance to water shortage conditions [41]. Myrothamnus falbellifolia (a terrestrial plant) and plants of Liliaceae family have been reported to synthesize glucosyl glycerol under drought stress conditions [42,43]. Transgenic potato plants were prepared by expressing ggpPS gene using 2 different types of promoters, i.e. CaMV35 and rd29A. Both type of transformed plants showed improvement in shoot length under both drought and saline stresses in green house conditions. Also, accumulation of GG was observed in leaves in both cases. But only rd29A transformants were able to accumulate GG in tuber [44]. Drought tolerance was introduced in potato plants by over expression of AtYUC6, as YUCCA family is known for its contribution in auxin biosynthesis. Potted transgenic plants of 4 months were evaluated, and they showed drought tolerance [25]. El-Banna et al. [45] used overexpression of gene regulating PR-10a (which is induced in osmotic/salinity stress) to control osmotic and salinity stress in potato callus. High proline accumulation and low oxidized glutathione was observed in transgenic callus in stress condition. Transgenic potatoes were developed by transferring sweet potato orange gene (ibOr). The transgenic plants were given drought stress in green house conditions. The transgenic lines showed improved resistances [46]. Thus, multiple researchers quoted above prove that there are a large number of genes which have important contribution for development of drought tolerance in potato plants.

Improvement of Salt Stress Tolerance in Potatoes

There are various implications of excessive soil salinity such as reduced yield and water potential, toxicity, alteration in metabolism of plants, ion imbalances and a drop-in assimilation of CO2. By the mid 21st century, a rise in arable land salinization seems to result in a loss of 50% of the arable land [47,48]. Potato has been categorized under moderately salt-sensitive crop; nonetheless, different potato cultivars respond differentially to salinity [49,50]. It has been identified that the Dehydration-responsive elementbinding (DREB)-1 TFs have been strongly induced under heat, drought, and high salinity as well as low-temperature stress conditions [51]. It has been elucidated that DREB1A and DREB2A TFs recognize DRE core sequence G/ACCGAC [52,53]. Additionally, DREB1A/CBF3 and DREB2A TFs specifically interact with cisacting dehydration-responsive element/C-repeat (DRE/CRT) region which play the role in drought and cold stress–responsive gene expression in A. thaliana [54]. Also, DREB1A/CBF1, DREB1A/ CBF3, DREB1B/CBF1 and DREB1C/CBF2 TFs have been found to be induced under low temperature stress conditions [55-57]. Bouaziz et al. [19] isolated StDREB2 gene from potato (cv. Nicola) plants and overexpressed it in transgenic potatoes, bioinformatics analysis of which unraveled that the StDREB2 protein belongs to the A-5 group of DREB subfamily. The overexpression in transgenic plants resulted in increased tolerance against salt stress. With the help of electrophoretic mobility shift assay (EMSA), they further found that this transcription factor was bound specifically to the DRE core element (ACCGAGA) in vitro. 𝛿1-pyrroline-5-carboxylate synthetase (P5CS) was increased in transgenics under salinity stress with collateral upregulation in proline accumulation inferring that StDREB2 might be responsive to abiotic stresses via ABA signaling regulation and through proline synthesis mechanism. In another similar study conducted by Bouaziz et al. [58], StDREB1 was found to be induced by drought, sodium chloride, cold temperature, and ABA. StDREB1 cDNA overexpression using pMDC32:StDREB1 construction in transgenic potatoes showed enhanced salt and drought stress tolerance in comparison to the control plants. As described above for StDREB2, the authors indicated that this increased stress tolerance could be due to P5CS-RNA expression as well the resulting proline osmoprotectant accumulation which also induced calcium-dependent protein kinases (CDPKs) stress responsive genes in standard and salt-stressed transgenics (Table 1).


Agrobacterium mediated transformation was used to transform DREB1A of Arabidopsis in Longshu3 (L3) cultivar of potato. Positive gene integration and over expression of gene was confirmed using PCR, Southern blotting and semi quantitative RT-PCR Analysis. The transgenic lines showed very partial wilting when water was withheld for 14 days as compared to non-transgenic plants, thereby confirming that over expression of DREB1A improved drought tolerance in potato plants [59]. In plants, the other TF group, NAC, might be involved in regulating transcriptional reprogramming associated with plant stress responses and is involved in stress responses in plants [60]. StNAC2 overexpression under the control of CaMV 35S promoter in transgenic potato yielded ameliorated tolerance to salt in vitro and drought tolerance in pot growing condition. Phytophthora infestans also induced StNAC2 expression in addition to its induction by salt, drought and wounding stresses, indicating the possibility of cross-talking of signaling molecules involved in biotic and abiotic stresses [61].

Potato cultivar Taedong valley was overexpressed using Gal- UR gene (D-Galacturonic acid reductase) isolated from strawberry under the control of CaMV 35S promoter and exhibited enhanced ascorbate (AsA). The study identified the function of GSH (Reduced glutathione), its regulation via ascorbate pathway enzymes and its role in improving salt tolerance in plants. GalUR gene in transgenics enhanced ascorbic acid content (L-AsA), and ultimate< ly reduced oxidative stress-induced damage leading to salinity tolerance improvement with tub erization even at 200mM of NaCl in transformants as compared to wild types [62]. HvNHX2, an Na+/ H+ antiporter gene from barley, under the control of CaMV 35S was transformed to potato cultivars Skoroplodny and Jubilei Zhukova which conferred improved tolerance to NaCl. At 200mM NaCl, Jubilei Zhukova-derived transgenics survived, whereas Skoroplodny couldn’t. The transgenic plant had enhanced dry weight, root length, and suppressed cell explansion than the non-transformants. Postassium was found to be elevated in the transgenic roots instead of sodium [63]. Plant cells are prone to salinity damages in two perspectives i.e. ionic stress and osmotic stress. Osmoregulation in plants by using osmoregulator substances, e.g. Mannitol, has been used to confer salinity tolerance in plants [64- 66]. Potato is among the plant species which do not accumulate mannitol naturally. Rahnama et al. [67] produced transgenic potatoes by taking the mannitol-1-phosphate dehydrogenase (mtlD) gene from E. coli Mt1D gene was proved to confer salinity tolerance to potato.

Improvement of cold stress tolerance in potatoes

The other stress that holds devastation for the cultivated potatoes is freezing temperature, and as potatoes being frost sensitive species, these plants are inept to thrive well under cold stress condition with maximum freezing tolerance threshold of -3 °C, both before and after exposure to freezing temperatures. Drop in temperature can bring about a plunge in various enzymatic activities with ice formation under low temperature, and ultimately dehydration in cytoplasm. There are some wild potatoes which are better frost tolerant than the cultivated species which could be potential genetic resource for its use in genetic improvement of cultivated potato crops [68,69]. It has been shown that the desaturase gene protein can be helpful in conferring cold resistant stress in plants [70]. Amiri et al. [71] demonstrated that the desA gene (acyl-lipid 12-desaturase) isolated from Synechocystis sp. PCC 6803 (cyanobacteria) transformed in potato lines could ameliorate the cold tolerance by varying lipid polyunsaturated fatty acid levels. Under cold stress, the study observed more sensitivity in control plants than those for desA gene introduced transgenic plants. The damage index in control plants was more at 7 °C in the control plants, whereas those for the three lines in transgenics were significantly reduced. Additionally, the study concluded that the desA protein has negative role on stem growth as the stem length in transformants reduced by nearly 60% than the control plants.

The S. tuberosum cv. Umatilla was overexpressed with AtCBF1-3 driven by CaMV 35S or a stress-inducible Arabidopsis promoter rd29A. Under CaMV 35S promoter, AtCBF1 and AtCBF3 increased freezing tolerance about 2 °C, whereas AtCBF2 transgenics couldn’t. Under rd29A promoter, transgenics exhibited same level of freezing tolerance in few hours, whereas CaMV 35S exhibited tolerance only under low temperature but not under freezing condition. Transgenics with AtCBF constitutive expression under freezing temperature exhibited smaller leaves, stunted growth, delay in flowering, and yield loss. Under the same freezing condition, transgenics driven by rd29A resulted in improvement of phenotype indicating use of stress inducible promoter to direct CBF transgene expression to ameliorate freezing tolerance in potatoes [72]. Pino et al. [69] further reported that the ectopic overexpression of AtCBF1 in frost-sensitive S. tuberosum and S. commersonii both induced COR gene expression devoid of cold stimulus and stimulated increase in tolerance against cold temperature of about 1-2 °C and 4 °C in transgenic S. tuberosum and S. commersonii respectively as compared to their wild types. The study highlighted that S. tuberosum has CBF regulated genes that can increase the freezing tolerance of plants grown at warm temperature. However, the authors suggest that there may be lack of additional cold-tolerant genes in potatoes that made it incapable for transgenic potatoes to increase chilling tolerance beyond those conferred by AtCBF1 overexpression as it was reported that the transgenic S. tuberosum showed no further gain in freezing stress tolerance under low temperature condition while S. commersonii could exhibit better acclimation to low temperature. Invertase gene was isolated from yeast and transformed in potato (cv. Desiree) under the control of B33 class 1 tuber-specific promoter. Invertase activity, content of sugar and cold tolerance were measured by MDA content in in vitro plants. Under controlled conditions in transgenic plants, invertase content and sugar content increased in leaves at 22 °C and MDA content enhanced as compared to the wild types. The authors have suggested that the invertase gene as a transgene might have conferred tolerance at chilling temperature apparently as a result of variation in sugar ratio [73].

Desiree cultivar of potato was transformed with the gene construct of A. thaliana derived AtDREB1A, the gene driven by the rd29A promoter from the same source, which showed enhanced freezing tolerance than the wild type. Also, in many of the transgenic lines, the authors observed recovery from freezing stress [74]. Improved salt tolerance at 75mM and cold tolerance was observed in transgenic potatoes (cv. Superior) when StEREBP1 was overexpressed under a constitutive CaMV 35S promoter inferring that StEREBP1 is another TF associated with abiotic stresses in plants. The yield in elite transformant improved by approximately 50% under cold stress. Also, it was observed that StEREBP1 binds to DRE/CRT and DCC cis-elements for its activity and microarray and RT-PCR techniques showed that many other stress responsive genes containing GCC box had been under the overexpression of StEREBP1 TF [75].

Increased cold stress resistance was induced in potato plants by transformation of soybean cold inducible zinc finger transcription factor (SCOF-1). The transgenic plants were kept under cold stress at 4 °C for 5 days. The expression of SCOF-1 correlated positively with the cold stress. The results showed that overexpression of SCOF-1 can efficiently increase the tolerance against freezing stress [76].

Improvement of Heat Stress Tolerance in Potatoes

Potato yield, mainly in the warm tropical region, is narrowed down by high temperature by hindering synthesis of starch in tubers [77]. The potato tuber growth optimal temperature is approximately 20 °C as potato is a cool-season crop [78]. The high temperature has been reported to cause build-up of glycoalkaloid in potatoes that alters the carbohydrate metabolism in tuber tissue leading to heat-induced damage of potato tubers [79]. Increased temperatures can also lead to a drop-in tuber dry matter accumulation. The tetraploidy of the cultivated potatoes makes potato genome more byzantine and high degree of sterility has precluded development of conventional breeding. This makes genetic engineering of potatoes to improve thermotolerance in potatoes inevitable [80]. Most small heat shock proteins (sHsps) are perceived only under heat stress in vegetative tissues and not under normal growth conditions. With increment in temperature up to 10-15 °C above the normal growth condition could actually be lethal to the organisms and eventually can induce heat shock response and stress tolerance in plants [81]. sHsps are adenosine triphosphate (ATP)-independent molecular chaperones which preclude irreversible aggregation or initiates correct refolding of the incorrectly folded or partially damaged proteins. In addition, many studies have reported incorporation of sHSP genes in ameliorating thermotolerance in various organisms [80]. Enhanced thermotolerance in the transgenic Desiree potatoes, probably the first one in potato, were obtained when the carrot gene that codes for heat shock protein (DcHSP17.7 gene) was transformed, regulated by CaMV 35S promoter. Under normal condition without stress, DcHSP17.7 expressed constitutively, though not in abundant amount. Transgenics showed ameliorated stability of the cellular membrane at increased temperature and prompt high tuber yield even at constant 29 °C stress when compared with the non-transformants. The study found that there was a good increase in percentages and dry weight of microtubes [80].

Transgenic potato cv. Atlantic which expressed cassava CuZn- SOD (Copper–zinc superoxide dismutase), pea APX (Ascorbate peroxidase) and Arabidopsis NDPK2 (Plant nucleoside diphosphate kinase 2) genes together under the control of stress-inducible SWPA2 promoter, all of these genes were shown to be ameliorating tolerance to high temperature stress and methyl viologen- induced oxidative stress. This transgenics (SSAN) showed enhanced tolerance to methyl viologen than the non-transgenics, SSA (transgenics with CuZnSOD genes and APX transgenes only) and SN (transgenics with NDPK2 only) plants. SSAN sprayed with 40μM methyl viologen resulted 53% less visible damage than SSA and 83% less than SN. Furthermore, high temperature tolerance as high as 42 °C was achieved in SSAN transgenics with only 6.2% reduction in photosynthesis rate than those grown at 25 °C, while this drop in rate was 50% for SN and 18% for SSA transgenics [82]. Dou et al. [83] isolated CBF3 gene from Arabidopsis which can be induced under cold stress, cloned under CaMV 35S promoter control as well as rd29A promoter and transformed the construct into the ‘luyin NO. 1’ potato cultivar. AtCBF3 could be expressed under heat stress even at the temperature higher than 40 °C. The accretion of O2 • − and H2O2 was declined in the transformants as compared to the non-transformants with increased D1 protein accumulation, net phososynthetic rate and maximal PSII photochemical efficiency in transgenics. The results inferred that the amelioration in heat stress tolerance was exhibited as a result of ectopic expression of AtCBF3 gene which enhanced photosynthesis and antioxidant defense. Nevertheless, HSP70 accumulation was lesser in transgenics than the wild types indicating HSP70 role was uninvolved in the pathway.

In another study, Kim et al. [84] overexpressed potato cultivar Atlantic with antioxidative enzyme 2-cysteine peroxiredoxin (2-Cys Prx) gene, which aids in eliminating peroxides and shields the photosynthetic membrane from oxidative damage, regulated by stress-inducible SWPA2 promoter or 35S promoter. The treatment with 3μM methyl viologen (MV) on both promoter-driven transgenics exhibited approximately 33% and 15% less damage than the wild type. Photosynthetic activity for SWPA2-promoter driven transgenics declined by 25% when 300μM MV was sprayed onto whole plants, whereas for non-transgenics it dropped further to 60%. SWPA2-driven transgenics could tolerate up to 42 °C.

Multiple tolerance against stresses including heat, oxidative stress, heavy metal and freezing was achieved in transgenic potatoes when ERF/AP2-type TF CaPF1 gene isolated from Capsicum annuum was cloned under the control of CaMV 35S promoter and the construct vector was transformed to Atlantic potato cultivar. However, the tuber formation in transgenics in vitro was severely impeded as compared with the wild-type [85].

Use of Transcription Factor for Introducing Tolerance Against Abiotic Stress in Potatoes

In addition to the genes directly related to different stresses, transcription factors also play a vital role in plants’ natural defense against various abiotic stresses. So, transformation of better transcription factor can be a good strategy to enhance tolerance of plants against various abiotic stresses [72,86,87]. Transgenic potatoes were developed in independent researches via transforming AtDREB/CBF gene. Different promoters were used in different researches i.e. rd29A [72,74,88,89] and 35S promoters [72,90]. The transgenic potato plant showed increased resistance against cold stress, salinity and drought tolerance [91]. Youm et al. [85] transformed a CaPF1 gene from Capsicum annuum in potato plants, this gene encodes the transcription factor AP2/ERF which has role in tolerance against cold stress and pathogens. The results showed an increased tolerance against drought, freezing, heat, heavy metal ions and oxidative stress in transgenic lines but tuber formation was retarded in these transformants as compared to non-transgenic plants. R2R3-type Myb TF has been reported to be involved in secondary metabolism and responding to biotic and abiotic stresses [92,93]. It is encoded by IbMybb1 gene. Cheng et al. [94] transformed this gene in potato plants which ultimately showed higher level of secondary metabolites (anthocynins, flavonoids and total phenols). These secondary metabolites are released in drought and UV-B ray stresses, thus the transformants showed better response under these stresses. Shin et al. [95] developed transgenic potato plants by transformation of StMyb1R-1 gene (a stress inducible gene) which encodes R-1 type MYB-like TF. The transgenic plants showed better response under drought stress.

Combination of Many Different Tolerances

Waterer et al. [96] developed potato cultivar Desiree by introducing transgenes under the control of 35S promoter or stress-inducible Arabidopsis COR78 promoter. Four types of transgenes were used: wheat mitochondrial MnSOD (SOD3.1), barley dehydrin 4 (DHN4), cold-inducible transcription factor DREB/ CBF from canola and stress-inducible brome grass derived ROB5 gene coding for LEA group 3-like protein. In total, six transgenics were used: COR78:: SOD3:1, COR78::DHN4, COR78::DREB/ CBF, COR78::ROB5, 35S::SOD and 35S::ROB5. Many of the transformed lines were reported to produce higher yield even at the significant drought stress. Under moisture stress, COR78::ROB5, COR78::DHN4 and COR78::SOD3.1 transgenics performed with higher yield with heat tolerance up to 44 °C. The tolerance was seen the highest for COR78::SOD3.1 transformants. At 10 °C, 35S::- SOD3.1 grew better than the non-transformants and COR78::- SOD3.1, 35S:SOD3.1 and 35S:ROB5 transgenics also showed improved tolerance against freezing stress.

StnsLTP1 is a potential gene from potato which was reported to be thermo-tolerant. Transgenic potato lines were developed which showed overexpression of this gene. The transgenic plants not only showed increased cell membrane integrity under stress conditions but also depicted increased antioxidant enzyme activity. The stress related genes (StAPX, StCAT, StSOD, StHsfA3, StHSP70 and StSHSP20) were also unregulated in transgenic lines [97].

Future prospective

Micro RNAs as a prospective candidate in improving abiotic stress tolerance in potato

Micro RNAs (miRNA) have been known to play an important role in various abiotic stress tolerance and some of them have been elucidated for transgenic plants. miR156 overexpression in Arabidopsis revealed enhanced tolerance to heat stress [98], constitutive overexpression of miR169 in tomato ameliorated tolerance against drought [99], miR319 overexpression in transgenic rice enhanced cold stress tolerance [100] and miR402 overexpression in Arabidopsis increased tolerance against drought, salinity and cold stresses in the transformants [82]. Similar type of miRNA or other miRNAs that have been explored to be involved in various abiotic stress tolerances can be studied by overexpression, silencing or other manipulations in potatoes which could improve the abiotic stress tolerance in cultivated potatoes.

CRISPR/Cas9, an emerging technology for improving abiotic stress tolerance in potato

A newly introduced technology Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein9 nuclease (Cas9) is revolutionizing the genetic engineering concepts in plants. CRISPR has been successfully implemented in various organisms including plants. It was first utilized in model plants like Arabidopsis, tobacco, and with passage of time it has been used for making genetic transitions in crops like maize, soybean, sorghum, wheat, woody plants, etc. [101-108]. Osakabe et al. [109] have used CRISPR for dealing with drought stress in Arabidopsis plants and they have achieved some success. But authors suggested that more studies are needed in this respect. CRIPSR/Cas9 has been utilized to study genes related to abiotic tolerance in plants. Two glycosyltransferase genes, i.e. UGT79B2 and UBT79B3, are thought to be responsible for making Arabidopsis plants tolerant in case of drought cold and salt stress. When these genes were knocked down by using CRISPR/Cas9 the plants became more susceptible to these stresses [110]. Shi et al. [111] utilized CRISPR/ Cas9 for generating transgenic maize with improved drought tolerance. Thus, studies need to be done in potatoes by utilizing the efficacy of CRISPR/Cas9 to enhance abiotic stress resistance in crop.

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Tuesday, October 19, 2021

Petrography of Hypabyssal Rock at Obiulo-Lekwesi-Lokpaukwu Area Southeastern Nigeria - Juniper Publishers

 Insights in Mining Science & Technology - Juniper Publishers

Abstract

The study area is in Lokpanta Formation of southern Benue Trough sedimentary terrain, in Abia State. The rocks are believed to have developed in early Cretaceous times and igneous activity was confined to this period in the Benue Trough. Major magmatism in the Mesozoic and Cenozoic formed the hypabyssal and pyroclastic rocks, due to opening of the Trough and its associated tectonism, of this well-defined continental rift setting. The effects of the heat supplied by igneous intrusives can be observed between the host rocks shales and dolerites as metamorphic aureoles, and the other rocks formed are hornfels at Obiulo-Lekwesi area. The petrography of the rocks indicates the phenocrysts minerals like pyroxene 20%, plagioclase 35%, olivine 14% and opaque minerals of Fe-Ti oxides, while quartz is low. The dolerites were emplaced in soft sediments and they are very hard. The rocks are of economic and industrial importance as aggregates for building houses, pavements, bridges, roads and railroad ballast. The mining pits which are several at Lokpaukwu, Lekwesi, Obiulo, Eziama, Lokpanta and Ishiagu areas are open pits filled with large volumes of water. They can be converted to fishing ponds so as to reduce the area from having badland topographical features. Presently, they pose health hazard to animals like cows and goats and even to human beings. The Environmental Impact Assessment (EIA) of the quarries were not carried out before establishing them for the quarrying of the aggregates for pavement and road construction purposes. All the mines surveyed have been abandoned without any remediation or reclamation procedures in place.

Keywords: Dolerites; Average Modal composition; Lokpanta Formation; Benue Trough; SE; Nigeria

Introduction

The study area is in Lokpaukwu-Lekwesi-Lokpanta axis located in Abia State southeast Nigeria. Its accessibility is through the Port Harcourt-Enugu dual carriage way and by foot paths or motorcycles. The dolerites are widespread and are emplaced in fracture systems that developed during the separation of Africa from North and South America [1]. The hypabyssal rocks are igneous intrusives which vary from medium-grained to fine-grained, and they are mostly dolerites, diorites, trachytes, unmappable pegmatite and granite-pegmatite rocks. They occurs less than 5m in-situ below the overburden shaly rocks. The initial mining pit locations were identified by the local communities and a major civil engineering firm, Forgerule Construction Company Nigeria Limited, in the 1980’s. They quarried the rocks for aggregates used in pavement construction of the Umuahia – Enugu section, of the 225km Port Harcourt - Enugu dual carriage way. The Figure 1 below indicates the insert Nigerian and Abia state maps, with the sample location map, coordinates Latitude 5° 53' N to 5° 59' N and Longitude 7° 21' E to 7° 31' E showing Leru, Lokpaukwu, Eluama and Lekwesi areas.

Geological Setting

The study area topography is undulating from the highlands of Leru in the south, with the Enugu escarpment running north-south at the western flank while the Abakaliki Anticlinorium is on the right. Figure 2a is the topographic and geological maps of parts of Leru-Lokpaukwu-Lokpanta axis. The shale outcrop covers the entire area and serve as host rock to the igneous intrusives. The area is within the tropical rainforest of southeast Nigeria, with an average rainfall of 1800mm-2050mm per year [2]. The drainage pattern is dendritic, with water flowing from the highlands in the west to east to join River Ikwo in Ishiagu area which flows southeast and joins the Asu River and Cross River drainage basin. The shale supports thick vegetation with trees, grasses, cassava, yams, coco-yams, bananas, plantain and palm trees growing very well. The Eze-Aku Group which forms the sedimentary cover in the study area, has been extensively studied by workers, on the geology of Nigeria in the area like Reyment [3], Amajor [4], Zarbosrki [5] and Ojoh [6], while its tectonism and magmatism has been studied by Ukaegbu [7], Onwualu-John & Ukaegbu [8] and Nwachukwu et al. [9]. The unusually carbonaceous rock in Lokpanta area was first reported by Petters & Ekweozor [10] and Ekweozor & Unomah [11]. However, as more recent data were obtained, they have re-defined the age and depositional environment of Eze-Aku Shale. The fact includes that the shale “black” colour may not necessarily always correlate with high organic matter content associated with sea-bottom anoxia. This was an underlying reason for this recent revision of the stratigraphy of what was hitherto regarded as ‘Eze-Aku Shale’, and the recognition of the ‘Lokpanta Shale’ as a member of the ‘Lokpanta Formation’ has recently been made [12]. The study area falls within Eze-Aku Formation and Lokpanta Formation that is Lokpaukwu and Obiulo-Lekwesi [12] and the geological map of the area modified after, is shown in Figure 2b.

Ekweozor [12] have on the basis of their very extensive geochemical campaign on the profiles of Eze Aku Group units has recently re-defined it. The Lokpanta Formation overlies Lokpanta, Lekwesi, Acha, Ugwueke and Ezeukwu areas; Eze Aku Formation is made up of Lokpaukwu and Aka Eze areas and this two formations form the Eze Aku Group, while parts of Asu River Group can be found at Uturu and Ishiagu areas, Figure 2b is a geological map of the area modified after [12]. The Figure 3 is the field photograph of the area showing the Enugu escarpment highlands running N-S in the west and top of the photograph of the study area and an abandoned open pit mine at Obiulo-Lekwesi area.

Materials and Methods

In this study, all the factors conditioning the exposure of the area was closely made and mapped. The elements of relief, highlands and lowlands was established using topographical map and field investigations as indicated on the field photographs. At the end of the survey, features of all the rocks and indices and names of various intrusive rocks were established and some of the rocks were un-mapable at the scale of the map. The intrusive rocks displayed sharp contact relationships with the host country rocks shale. Thirty rock samples were obtained from the field survey and twenty-five representative sections were sampled for thin sections and petrographical analysis. The observations made include individual grain boundary and dislocation substructure. The average modal composition of the rocks were obtained and compared with previous data obtained elsewhere.

Results and Discussion

The dolerites (olivine diabase) colour are of different types, dark grey to black or green, some spotted like skin of the leopard when fresh, the grain size is medium-grained, fresh to weathered and there are traces of pegmatite at some sections in the mining pits. This may probably be due to variable ferromagnesian minerals and trace elements composition and weathering profiles of the exposed rocks in the mining pits. The overburden material varies in thickness from one part of the mining pit to another. The deepest part is in the south while the north is shallower. The depth ranges from 3m to 4.5m and the lithology indicates laterite 0.5m, dark shale 2.0m, grey shale 1.5m, bioturbated shale 0.4m and slate/phyllites <0.1m. In some locations, the heat from the igneous intrusions have metamorphosed the shale to slate/phyllites which indicates contact metamorphism and around the rocks, and there are presence of metamorphic aureoles. There is evidence of all the three rock types sedimentary, metamorphic and igneous rocks occurring in the area at various thickness, which can be observed at the locations where local miners mine dolerites at a depth of 1.5m to 3m Figure 4.

The dolerites texture is ophitic and in hand specimen, can be distinguished from gabbro and it may also be porphyritic. The structure shows vesicles and amygdales occurs. Sometimes it has segregations of coarser rock enriched in feldspar. The mineralogy shows phenocrysts comprise olivine (olivine diabase) and/or pyroxene or plagioclase. The groundmass comprises the same minerals with iron oxide, and sometimes with some quartz, hornblende or biotite. The field relationships are dykes and/or sills. They formed swarms of hundreds or perhaps thousands of individual dykes or sills which often radiate from a single volcanic centre as shown in Figure 4. The filed photographs of the mining pits where the rocks were obtained for thin sections and petrographic studies are shown in (Figures 5-7), while Table 1, is the average modal composition of the rocks analyzed and comparison with similar rocks analysis elsewhere.

Discussion

The Cenozoic volcanism in parts of West Africa is of alkaline affinity [1], while Onwualu-John and Ukaegbu [8] using geochemical evaluation in Southern Benue Trough identified two groups; one having an alkaline affinity and the other with a tholeiitic affinity and contains these minerals ortho-pyroxene, calci-plagioclase and clino-pyroxene. In the Oban massif and Obudu Plateau southeast basement complex areas of Nigeria, the fine to medium grained varieties have been identified with similar characteristics by Ekwueme [13]. Minerals like cordierite, hypersthene, and sillimanite were also identified in the gneisses that are in contact with dolerites in this basement terrain. The Obiulo dolerites are fine- to medium- grained and the fine-grained texture is a reflection of their shallow level emplacement which favoured quick cooling as compared to deep emplacement that will favour slow cooling with texture medium-to coarse-grained. They have ophitic texture and the contact of these dolerites with the host shale rocks are chilled and metamorphosed as shown on the field photographs Figures 4 & 8. Dolerites have been observed as un-mappable exposure along Enyi Boje – Ebok road in meta-sediments and also at Kanyang quarry a granulites environment, in Bansara and Mukuru area with chilled margin and contact metamorphic aureole Egesi [14]. Sholokwu and Egesi [15] and Oyefeso and Egesi [16] also identified minor intrusive rocks; dolerites, charnockites and granites in association with basement rocks migmatites, gneisses and schists in the boundary area between Obudu sheet 291 and Mukuru sheet 305 Table1. In Lekwesi area, Nwokeabia et al. [17] using Vertical Electrical Sounding (VES) and microscopic study identified diorite with mean density 2.88 × 10³ Kg/m³ in an investigation to determine the rocks viability for the establishment of a quarry operation. They observed that the diorite deposit found at the location, is 5.8m thick, while the overburden materials was estimated be 10.49m and concluded that it not economical for large-scale quarrying operations, except for small scale enterprise [18].

Conclusion

The mining pits which are several at Eziama-Lokpaukwu area is in Eze-Aku Formation, while Obiulo-Lekwesi is in Lokpanta Formation and Ishiagu is in the Asu River Group areas have igneous intrusives which are hypabyssal rocks dolerites, microdiorites and diorites, and they ranges from 25m overburden depth in Ugwu-ele mining pit at Uturu area to less than 3m at Obiulo-Lekwesi area. The petrographic analysis indicates mainly dolerites with contact metamorphic auroles and thin section analysis showing the phenocrysts as mainly plagioclase, pyroxene, olivine and minor quartz and opaque minerals and the values of the average modal compositions of the rocks are comparable to the results obtained elsewhere.

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Monday, October 18, 2021

Dependence of Chlorophyll Content in Leaves from The Light Regime, Electromagnetic Fields and Plant Species Alexander Kholmanskiy* and Nataliya Zaytseva - Juniper Publishers

 Horticulture & Arboriculture - Juniper Publishers


Abstract

The regularity of the distribution of chlorophylls content in a series of 30 cultivated plants and 75 steppe grasses was studied. The increased content of chlorophyll and magnesium in vegetables and grains compared with greens and steppe grasses is associated with more complex genetics of metabolism, which has stages of flowering and fruiting. The chlorophyll content increases with the use of LED phytoirradiators with an emission band coinciding with the first absorption band of chlorophyll. Industrial electromagnetic fields can affect the biosynthesis of pigments in deciduous trees, but cultivated herbaceous plants are not sensitive to them.

Keywords: Content; Chlorophyll; Magnesium; Phytoirradiators; Vegetables; Grains; Grass

Introduction

The productivity of photosynthesis of green plants is determined mainly by their genetics and strongly depends on temperature, nutrient medium and light regime Polevoj [25]; Andrianova & Tarchevskij [2]. These factors determine the structure and efficiency of the Photosynthetic Apparatus of the plant (PSA). The key functional elements of PSA are a and b forms of the Chlorophyll (Chl) Senge [28]; Kholmanskiy & Smirnov [16] and water, which plays the role of a dynamic matrix and active metabolite Polevoj [25]; Kholmanskiy & Tilov [13]; Aksenov [1]. Water sensitizes PSA by forming complexes with Mg and chiral centers Chl Kholmanskiy & Smirnov [16] and other molecules in the composition of PSA Senge [28]; Kholmanskiy [14]; Kholmanskiy [15]; Zaytseva & Sitanskaya [37]. The abnormal thermodynamic properties of water optimize the physics of cold stratification of seeds at a temperature of about 4°C Kholmanskiy [15] and minimize the energy of seed germination and photosynthesis in the temperature range 15-25°C Polevoj [25]; Kholmanskiy [15]. The photo- and thermophysics of Chl substantially depend on the Mg ion in the center of porphyrin cycle and the electronic nature of substituents in it Senge [28]; Kholmanskiy & Smirnov [16]. In principle, chlorophyll can play the role of a marker of the total Mg content in a plant and therefore can be considered an adequate characteristic of the nutritional value of a plant product.

The photochemistry and photo physics of PSA are determined primarily by the electronic structure of the ground and excited electronic states of Chl. A significant difference in the biophysics of chlorophyll Chl a and Chl b Tyutereva & Ivanova [35] is caused by the replacement of the CH3 group by the electron-acceptor and proton donor groups of CHO in the 7th position of pheophytin (Figure 1). In Frese [9]; Kholmanskiy & Smirnov [16], the electronic nature of the ground and lower excited states of Chl was attributed to states with charge transfers whose dipoles are oriented along the mutually orthogonal X and Y axes of the Chl molecule. The high dipole moments of the excited states of Chls initiate electron and proton transfers from other PSA components and these reactions can accelerate the kinetics of photochemical reactions in PSA. It was suggested in Kholmanskiy [18] that micro polarization of PSA promotes proton diffusion in leaves and intensifies the extraction of micro and macro cell ions by a plant. Mg and Chl greatly increase the nutritional and medicinal value of cultivated plants, both leafy and fruit-bearing. In Kholmanskiy [17-18] it was established that the efficiency of Mg extraction by plant leaves of cultivated plants depends on their species and responds to changes in the irradiation spectrum. It can be assumed that a similar dependence should be observed for the content of Chl in plant leaves. To deepen understanding of the biophysical relationship between plant productivity and Chl we compared the total content of a+b Chl and Mg in raw samples of leaves of a number of cultivated plants and steppe grasses. We analyzed the dependence of the Chl content in the leaves of cultivated plants on the light regime, and also compared the effects on photosynthesis of Chl a and Chl b in plantain and wheat seedlings of an electromagnetic industrial Novichkova & Podkovkin [23]; Shashurin [27] and an electrostatic vortex field Therapeutic reel Mishina [33].

Results and discussion

The empirical data on the content of chlorophylls a and b in cultivated plants and grasses were taken from books and works published by us and other authors. Table 1 shows the total content of Chl a+b (hereinafter [Chl]) and the ratio a/b for raw samples of plant leaves. The determination of [Chl] in the works was carried out according to the methods described in Lichtenthaler & Buschmann [21]. In Bohn [3] [Chl] was determined using liquid chromatography, and the Mg content in Chl was calculated based on its mass fraction of ~2.7% in a and b Chl. In this work, we compared the concentrations of total Mg and Mg in the composition of Chl (Table 2).

A large scatter of [Chl] values in different works is caused by differences in both their measurement methods and the growing conditions of the same plants. The [Chl] values determined for dry samples were recalculated for the wet state using a drying coefficient (k). It was evaluated by determining the weight of a fresh sample and after drying it at a temperature of no higher than 40°C. For vegetable crops (tomato, cucumber), leaf (lettuce, greens) and steppe grasses their k were: 8.5; 15-20 and 6-7, respectively. At the same time, the proportion of water in raw samples was determined by the ratio (k-1)/k and was equal to: 88%; 93-96% and 85-86%, respectively.

The Table 1 shows [Chl] values for plants growing in natural and greenhouse conditions. In the latter case, the age of the samples (weeks) and the light regimes were varied. The irradiators included various combinations of Blue (Bl), Green (Gr), Red (Rt) Light Emitting Diodes (LED1 and LED2) Kholmanskiy [18] and 400W high pressure sodium (SL) and mercury (ML) lamp. Their emission spectra and the absorption spectrum of Chl are shown in Figure. In some works, the LED composition included a diode emitting in the far-red region of the spectrum (FRt) with a maximum at 730nm. Plant species in Table 1 are divided into three groups: vegetables, cereals, berries (I); lettuce and greens (II); grasses (III). The mean values of [Chl] in the II and III groups are close and 1.6 times less than in the I group. At the same time, [Chl-b] in the I-st III-th is 2 times less than [Chl-a], and in the II-th one 3.3 times. The value of [Chl] in the first and second groups of plants reaches a maximum at 3 weeks of growth and depends on the spectral composition and intensity of irradiation. The Сhl content decreases when the irradiation intensity is exceeded by the norms of the optimal light regime Dalke [7]. Moreover, the Chl photo destruction reaction can contribute to the negative effect Kholmanskiy & Smirnov [16]. The efficiencies of Chl biosynthesis in the leaves of plants of group I are close when the plants are irradiated with LED irradiators and the sun and are higher than when irradiated with SL. This result can be explained by the good overlap of the Rt emission bands of LED1 and LED2 with the first absorption band of Chl a and b (Figure 2). In group II, the dependence of the efficiency of Chl biosynthesis on the irradiation spectrum is less pronounced. Chl biosynthesis is limited by the efficiency of the plant’s extraction of the Mg, which depends on the type of plant and the irradiation spectrum Kholmanskiy [18]. Table 2 shows the total content of Mg, Chl, and Mg in Chl ([Mg-Chl]) in the leaves and fruits of plants of the first and second groups, for samples grown under irradiation ML. From these values, the concentration ratio of total Mg to Mg in the composition of Chl (Mg/[Mg-Chl]) was calculated.

The obtained relations Mg/[Mg-Chl] indicate that the total Mg content in plants significantly exceeds [Chl], and this disproportion in plants of the 1st group is 4-5 times greater than in plants of the 2nd group. This is due to the fact that Mg is included in the active center of the enzyme, providing assimilation of CO2 Polevoj [25] and also participates in the activation of many other complexes Senge [28]; Shkol’nik [29]; Sukovataya [32]. In addition, the genetics of cucumber and tomato, unlike lettuce, includes programs for the stages of flowering and fruiting with their specific biochemistry and bioenergy Shkol’nik [29]; Tikhomirov, Sharupich [34]. A significant contribution to the intensification of photosynthesis and enzymatic reactions in animal and plant organisms is made by the magnetic isotope 25Mg Buchachenko [5] the content of which in natural magnesium is 10%. Apparently, 25Mg in the composition of enzymes plays an important role in the functioning of the phytochrome and cryptochrome PSA systems, activating magnetically sensitive dark reactions of radical ion pairs Evans [8]. Chl charge transfer states in dark reactions relax with the formation of long-lived excitons Frese [9]. Their participation in the work of PSA can, in principle, determine the dependence of the efficiency of photosynthesis on external electromagnetic and electric fields. To verify this assumption, we compared the dependence of the content of pigments - Chl a, Chl b and carotenoids (k) in maple leaves growing at a distance of 0 to 1000m (control) from 110kV power lines Novichkova & Podkovkin [23] and in the leaves of plantain seedlings, grown in an Electromagnetic Field (EMF) with a frequency of 50Gz and different intensities Shashurin [27], as well as wheat seedlings growing in an electrostatic vortex field with a frequency of 300kGz Therapeutic reel Mishina [33]. Recent experiments were carried out by us, using similar methods Kholmanskiy & Smirnov [16]; Kholmanskiy [18]. The results and experimental conditions are shown in Table 3. The errors in measuring the pigment content in all samples were about 10%. From the data of Table 3 it follows that the influence of EMF affects the efficiency of pigment biosynthesis only in a tree. The reason for this may be the elongation of transport communications along which charged mineral elements move from bottom to top, and phytohormones from top to bottom. The electrophysical properties of the sap in the layers of cambium and sapwood of deciduous trees, in contrast to the resin of conifers, contribute to electro tropism Kholmanskiy [12].

Conclusion

Thus, it was found that the content of chlorophyll and magnesium in the leaves of cultivated plants is significantly higher in fruitful species than in leafy and, especially in steppe grasses. The chlorophyll content increases when growing plants in light regime using LED irradiators having a radiation band that overlaps well with the first absorption band of chlorophyll a and b. Differences in the content of chlorophyll and plant productivity are associated with a more complex genetic program of metabolism in higher cultivated plants, including the stages of flowering and fruiting.

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Wednesday, October 13, 2021

The Importance of Wildlife and Biodiversity - Juniper Publishers

 Wildlife & Biodiversity - Juniper Publishers

Abstract

Biodiversity is a complete term for the extent of nature’s variety or variation within the natural system, both in number and frequency [1]. It’s often being understood in terms of the wide variety of plants, animals and microorganisms, the genes they contain and the ecosystem they form [1]. Today’s biodiversity is the result of billions of years of evolution, shaped by natural processes and, increasingly, by the influence of humans [1]. It forms the web of life of which we are an integral part and upon which we so fully dependent. Biodiversity also includes genetic differences within each species - for example, between varieties of crops and breeds of livestock. Chromosomes, genes, and DNA-the building blocks of life-determine the uniqueness of each individual and each species [2]. It is necessary to know Current scenario about wildlife protection and conservation at national and international level [2]. Habitat conservation is the key solution to conserve biodiversity [3]. Lot of efforts has been done to encourage forestation and decrease deforestation and practices has been done in many areas[3]. Similarly, by discouraging the pet trades, over shooting as well as hunting by applying different banes, marine pollution by different laws and regulations, and public awareness are the main concerns. Conservation of biodiversity is a great challenge in current scenario [3].

Keywords: Biodiversity; Biodiversity conservation; Natural forests; Wildlife; Ecosystems

Introduction

Biodiversity is a short form for biological diversity which refers to the sum total of all the variety and variability of life in a defined area. The term biodiversity was used to emphasize the many complex kinds of variations that exist within and among organisms at different levels of organization. It refers to the totality of genes, species and ecosystems of a region [4].

Biodiversity is considered at three major levels:

i. Genetic diversity: This is the variety of genetic information contained in all of the individual plants, animals and microorganisms occurring within populations of species. Simply it is the variation of genes within species and populations [4].

ii. Species diversity: This is the variety of species or the living organisms. It is measured in terms of Species Richness. This refers to the total count of species in a defined area.

iii. Ecosystem diversity: This relates to the variety of habitats, biotic communities and ecological processes in the biosphere [4].

Ethical and moral benefits includes every form of life on earth is unique and warrants respect regardless of its worth to human beings; this is the ecosystems right of an organism [5]. Every organism has an inherent right to exist regardless of whether it is valuable to human beings or not [5]. Planted forest also plays significant role in biodiversity conservation and also reduce the pressure on natural forests. Both FRA (Forest Resources Assessments) and FAOSTAT data shows that if globally planted forests get increased by 2.4% per annum from 2010-2050 it might restore natural forests for fibers as well as timber [5]. Humankind is part of nature and the natural world has a value for human heritage [6]. The well-being of all future generations is a social responsibility of the present generations, hence the existence of an organism warrants conservation of the organism [6]. Human beings derive great enjoyment from natural environment. The shapes, structure and colour stimulate our senses and enrich our culture [7].A lot of money is paid to conserve wildlife for their value in nature through so many organizations. The greatest threat to biodiversity is habitat loss [7]. Variations in Biodiversity occurs with changes in latitude or altitude. As we shift from the poles to the equator, the biodiversity increases and vice versa . The latitudinal gradient in species refers to the increase in species richness or biodiversity that occurs from the poles to the tropics. Latitudinal gradient in species is one of the most widely recognized patterns in ecology. Like latitudinal variation, changes in the biodiversity also occurs due to altitudinal variation. A decrease in species diversity occurs when shifted from lower to higher altitudes on a mountain. There are various benefits of biodiversity [8]. More than 60 wild species have been used to improve the world’s 13 major crops by providing genes for pest resistance, improved yield, and enhanced nutrition (IUCN, 2012) [8]. Fisheries alone account for at least 15% of animal protein directly consumed by humans. Like in USA (technologically-advanced country) most of the drugs are provided by medicinal plants and animal’s people use [9]. More than 70,000 different plant species are used in traditional and modern medicine [9]. Microbes have given us nearly all of our antibiotics such as penicillin as well as the cholesterol lowering strain. Ecosystem services are the processes and conditions of natural systems that support human activity [10]. The function of the ecosystem and the services they provide are completely governed by biodiversity [10]. A major role in mitigating climate change by contributing to long term sequestration of carbon in a numb is played by biodiversity [11]. Absorption and breakdown of pollutants and waste materials through decomposition, e.g., in food webs and food chains where the flow of energy goes through production consumption and decomposition without which breakdown and absorption of materials will not be complete [12]. In an ecosystem there is no waste as because decomposition will take place to purify the environment by converting the waste to other forms of biodiversity [13]. Every form of life on earth is unique and is respectable regardless of its worth to human beings; this is the ecosystems for an organism [14]. Whether an organism is valuable to human beings or not it has an inherent right to exist [14]. Humankind is part of nature and the natural world has a value for human heritage [15]. The well-being of all future generations is a social responsibility of the present generations; hence the existence of an organism warrants conservation of the organism [16]. Human beings derive great enjoyment from natural environment [17]. Our senses are being stimulated by the shapes, structure and colour which enriches our culture [17]. This illustrates majorly in the popularity of biodiversity conservation measures and the myriad of the many organizations which fight for the protection of different organisms [18]. Many organizations pay to conserve wildlife for their value in nature [18]. Wild species enhance our appreciation and enjoyment of the environment through leisure activities, for example bird watching and nature trailing; Spotting activities for example spot hunting, sport fishing, diving and mushroom picking; hearing, touching or just seeing wildlife [19]. There are principle threats to biodiversity, which refers to any process or event whether natural or human induced that is likely to cause adverse effects upon the status or sustainable use of any component of biological diversity [19]. Due to factors such as habitat alteration and destruction by the land use change, over exploitation of biological resources, climate change, pollution and invasive species Biodiversity is declining rapidly [20]. Such natural or human induced factors tend to interact and amplify each other [20]. The contemporary biodiversity decline will be leading to subsequent decline in the functioning and stability of ecosystem. Ecosystem functioning often depends on species richness, species composition and also on species evenness and genetic diversity. Stability often depends on species richness and species composition. Thus, contemporary changes in biodiversity will likely lead to subsequent changes in ecosystem properties [20].

Conclusion

Biodiversity conservation is all about saving life on Earth in all its forms and keeping natural ecosystems functioning and healthy [21]. Biodiversity is the life support system of our planet- we depend on it for the air we breathe, the food we eat, and the water we drink [21]. Medicines originating from wild species, including penicillin, aspirin, Taxol, and quinine, have saved millions of lives and alleviated tremendous sufferings [22]. Wetlands filter pollutants from water, trees and plants reduce global warming by absorbing carbon. Bacteria and fungi break down organic material and fertilize the soil [22]. It has been observed that native species richness and the health of ecosystems are linked, as is the quality of life for humans [22]. The connections between biodiversity and the sustainable future appear closer and closer the more we look. We literally need to conserve biodiversity as our lives depend on it [23]. We should address the underlying causes of biodiversity loss by mainstreaming biodiversity across government and society , reduce the direct pressures on biodiversity and promote sustainable use, Improve the status of biodiversity by safeguarding ecosystems, species and genetic diversity , Enhance the benefits to all from biodiversity and ecosystem services, Enhance implementation through participatory planning, knowledge management and capacity building [24].

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Tuesday, October 12, 2021

Traumatic Localized Dupuytren Disease - Juniper Publishers

 Orthopedic & Orthoplastic Surgery - Juniper Publishers

Abstract

We present a Case series of four patients who attended the clinic complaining of a localized lump formation after a specific trauma, which ended being a form of localized Dupuytren. We discuss the still unclear etiology of this disease on comparison to the specific relationship of those cases to trauma.

Keywords: Localized dupuytren; Traumatic contracture

Introduction

Dupuytren’s contracture is a benign fibro-proliferative disease of the hand causing fibrotic nodules and fascial cords which determine debilitating contracture and deformities of fingers and hands. There are characterized by a disorder of the extracellular matrix and high myofibroblast proliferation. Different investigators have proposed many theories and documented several findings regarding the aetiology of Dupuytren’s contracture affecting large area of the hand, but there are not references to more localized tumor-like disease clearly and directly associated to trauma.

Methods

Three women and one man attended in different occasions the clinic complaining of a localized lump formation associated in some of the cases with reduction of joint movement affecting fingers or palm of the hand, caused by a specific direct trauma to the area where the disease appeared and with an involvement of a maximum two and a half to three centimeter of length, and all of then forming a fascial cord of Dupuytren. MRI scan were organized for all the cases, previous to the surgical treatment, and histopathological results were sought to confirm the disease.

Objective and Discussion

The aim of this study was to present the cause-specific incidence of trauma in the development of Dupuytren disease (DD). Presenting a case series of four cases of Traumatic Localized Dupuytren disease appearing as a result of a direct trauma in a specific area of the hand with no progression of the disease. Most studies have found relationships between the disorder and manual labor, previous hand injures, genetic susceptibility, diabetes mellitus, epilepsy, high cholesterol level profile and intake of either alcohol or tobacco. However, according to others, the evidence on risk factors associated with certain lifestyles has been conflicting [1].

Several authors who focused their studies on the genetics of DD recognized an inherited autosomal dominant pattern. Actually, DD is thought to be a multifactorial and complex disease. Myofibroblasts are thought to play a crucial role in its pathogenesis, although their origin is not clear, also Transforming growth factor beta (TGF-beta) is thought to play a role in its pathogenesis [2]. Traumatic events or vibration have been found to have influence on the development of this illness and are likely to trigger different clinical forms of this disease [3,4].

Despite that there was an extended idea that microtraumas may developed the disease, there is not proved evidence that hand injuries or occupations that involve vibrations to the hands cause the condition [5]. In all those reports the relation between the DD and the origen or cause of the disorder was refer to the well-known full developed disease with affectation of the palm and one, two or more digits, in our cases the direct trauma affecting only a small specific area of the hand, clearly produced a localized DD more often seen in the digits with not expansion to the palm of the hand or other fingers.

Result

Pathology confirmed in all the cases the diagnosis of DD. Al the patients remember clearly the traumatic event that produced the reaction. Only one refer family history, and neither of them have any of the recognized risk factors associated to Dupuytren. Most of the cases came to consultation with a previous diagnosis of soft tissue tumor.

Conclusion

Despite the correlation between trauma and Dupuytren contracture has not been proved, this small case series confirmed that trauma has an important role on the developing of a localized form of this disease, even in patients that have neither of the risk factors associated to the condition and could be the answer to some unknown tumor-like formation in the hand.

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