Abiotic Environmental Stresses Research Articles

ROLE OF CRISPR TO IMPROVE ABIOTIC STRESS TOLERANCE IN CROP PLANTS

The study for genetic variation in plant genomes for a variety of crops, as well as developments of genome editing techniques, have made it possible to cultivate for about any desired trait. Zinc finger enzymes; have made strides in genome-editing. Molecular biologists can now more specifically target every gene using transcription activator-like effector nucleases and ZFNs. These methods, on the other hand, are expensive and time-consuming because they involve complex procedures. Referring to various genome editing techniques, CRISPR/Cas9 genetic modification is simple to construct and clone and the Cas9 could be used with different guide RNAs controlling different genes. Following solid evidence demonstrations using the main CRISPR-Cas9 unit in field crops, multiple updated Cas9 cassettes are often used in plant species to improve target precision and reduce off target cleavage. Nmcas9, Sacas9, as well as Stcas9 are a few examples. Furthermore, Cas9 enzymes are readily available from a variety of sources. Bacteria that had never been discovered before has found solutions available to improve specificity and efficacy of gene editing techniques. The choices are summarized in this analysis to plant's experiment to develop crops using CRISPR/Cas9 technology; the tolerance of biotic & abiotic stress may be improved. These strategies will lead to the growth of non-genetically engineered crops with the target phenotype, which will further improve yield capacity under biotic & abiotic stress environments.

Metagenomic analysis reveals genetic insights on biogeochemical cycling, xenobiotic degradation, and stress resistance in mudflat microbiome

Mudflats are highly productive coastal ecosystems that are dominated by halophytic vegetation. In this study, the mudflat sediment microbiome was investigated from Nalabana Island, located in a brackish water coastal wetland of India; Chilika, based on the MinION shotgun metagenomic analysis. Bacterial, archaeal, and fungal communities were mostly composed of Proteobacteria (38.3%), Actinobacteria (20.7%), Euryarchaeota (76.1%), Candidatus Bathyarchaeota (6.8%), Ascomycota (47.2%), and Basidiomycota (22.0%). Bacterial and archaeal community composition differed significantly between vegetated mudflat and un-vegetated bulk sediments. Carbon, nitrogen, sulfur metabolisms, oxidative phosphorylation, and xenobiotic biodegradation were the most common microbial functionalities in the mudflat metagenomes. Furthermore, genes involved in oxidative stresses, osmotolerance, secondary metabolite synthesis, and extracellular polymeric substance synthesis revealed adaptive mechanisms of the microbiome in mudflat habitat. Mudflat metagenome also revealed genes involved in the plant growth and development, suggesting that microbial communities could aid halophytic vegetation by providing tolerance to the abiotic stresses in a harsh mudflat environment. Canonical correspondence analysis and co-occurrence network revealed that both biotic (vegetation and microbial interactions) and abiotic factors played important role in shaping the mudflat microbiome composition. Among abiotic factors, pH accounted for the highest variance (20.10%) followed by available phosphorus (19.73%), total organic carbon (9.94%), salinity (8.28%), sediment texture (sand) (6.37%) and available nitrogen (5.53%) in the mudflat microbial communities. Overall, this first metagenomic study provided a comprehensive insight on the community structure, potential ecological interactions, and genetic potential of the mudflat microbiome in context to the cycling of organic matter, xenobiotic biodegradation, stress resistance, and in providing the ecological fitness to halophytes. These ecosystem services of the mudflat microbiome must be considered in the conservation and management plan of coastal wetlands. This study also advanced our understanding of fungal diversity which is understudied from the coastal lagoon ecosystems.

Plant-Microbe Interactions in Alleviating Abiotic Stress—A Mini Review

Crop plants are continuously exposed to various abiotic stresses like drought, salinity, ultraviolet radiation, low and high temperatures, flooding, metal toxicities, nutrient deficiencies which act as limiting factors that hampers plant growth and low agricultural productivity. Climate change and intensive agricultural practices has further aggravated the impact of abiotic stresses leading to a substantial crop loss worldwide. Crop plants have to get acclimatized to various environmental abiotic stress factors. Though genetic engineering is applied to improve plants tolerance to abiotic stresses, these are long-term strategies, and many countries have not accepted them worldwide. Therefore, use of microbes can be an economical and ecofriendly tool to avoid the shortcomings of other strategies. The microbial community in close proximity to the plant roots is so diverse in nature and can play an important role in mitigating the abiotic stresses. Plant-associated microorganisms, such as endophytes, arbuscular mycorrhizal fungi (AMF), and plant growth-promoting rhizobacteria (PGPR), are well-documented for their role in promoting crop productivity and providing stress tolerance. This mini review highlights and discusses the current knowledge on the role of various microbes and it's tolerance mechanisms which helps the crop plants to mitigate and tolerate varied abiotic stresses.

Identification and analysis of non-specific lipid transfer protein family in tobacco

Plant non-specific lipid transfer proteins (nsLTPs) can transfer lipids in vitro , regulate plant growth and development, and respond to environmental abiotic and biotic stresses. In this study, 74 nsLTPs genes were identified from the genome of Nicotiana tabacum variety K326, and we analyzed multiple characteristics of these genes, including phylogeny, gene structures, conserved motifs, protein domains, chromosome locations, cis -elements in the promoter sequences, 3D structure, and the expression patterns under different hormones and abiotic stresses. The results revealed that nsLTPs in tobacco could be divided into eight types, including type I, II, III, IV, V, VII, VIII, and XIII, according to the interval and sequence similarity between the eight cysteines. The same types of NtLTPs had similar intron-exon patterns and conserved motifs, motif 2 and motif 3 were the characteristic motifs of NtLTPs family. In the process of evolution, fragment duplication dominated the expansion of the NtLTPs family. RNA-seq analysis after drought treatment revealed that the functional differentiation patterns of repeat gene pairs were diverse during evolution period. Promoter analysis showed that they contained a variety of cis-acting elements in response to light response, hormones, and abiotic stress. Furthermore, qRT-PCR demonstrated that NtLTPs family genes had different expression patterns in different tissues and organs of tobacco plants, which could respond to abiotic stresses such as drought, salt, and hormone treatments (IAA, GA, and SA etc.). These results provide a theoretical reference for the in-depth analysis of the functions of NtLTPs family genes and molecular breeding.

Sex-specific differences in Juniperus communis: essential oil yield, growth-defence conflict and population sex ratio.

In plants, biomass and nutrient allocation often generate trade-offs between the different biochemical pathways conflicting the utilization of the common source among growth, reproduction and chemical defence. However, in dioecious plant species, these trade-off patterns could appear as a more contrasted problem between males and females due to the dissimilar reproduction investment. Generally, the growth ratio is higher in males than females, while females have a stronger defence than males. To understand the possible role of the sex-specific dissimilarities within the growth-defence conflict framework, we investigated the possible causes of the high variance of the essential oil yield in a dioecious evergreen species, Juniperus communis. Specifically, we tested the correlations between the essential oil yield with other individual-specific traits (e.g. sex, age), the presence of the growth-defence trade-off, and the differential growth and survival patterns between males and females through an extensive field survey with sample collection in three natural populations (Kiskunság National Park, Hungary). The individual-specific essential oil yield was also measured and served as a proxy to describe the degree of chemical defence. We found that the essential oil yield showed strong and consistent sex-specific patterns decreasing with age in adults. Contrary to the predictions, the males showed a consistently higher yield than the females. We also observed a growth-defence trade-off in males but not in females. Consistently with the growth-defence conflict hypothesis, the populations’ sex ratio was male-biased, and this pattern was more evident with ageing modifying the demographic structure due to the sexually dissimilar lifespan. Our juniper study revealed a contrasting and unique essential oil accumulation driven by the complex allocation trade-off mechanisms within individuals, which could be a flexible and adaptive defence response against the increasing biotic and abiotic environmental stresses exacerbated under global climate change.

OsIAA20, an Aux/IAA protein, mediates abiotic stress tolerance in rice through an ABA pathway

In plants, auxin and ABA play significant roles in conferring tolerance to environmental abiotic stresses. Earlier studies have been shown that some Aux/IAA genes, with important signaling factors in the auxin pathway, were induced in response to drought and other abiotic stresses. However, the mechanistic links between Aux/IAA expression and general drought response remain largely unknown. In this study, OsIAA20, a rice Aux/IAA protein, shown with important roles in abiotic stress. Phenotypic analyses revealed that OsIAA20 RNAi transgenic rice reduced drought and salt tolerance; whereas, OsIAA20 overexpression plants displayed the opposite phenotype. Physiological analyses of OsIAA20 RNAi rice grown under drought or salt stress showed that proline and chlorophyll content significantly decreased, while malondialdehyde content and the ratio of Na+/ K+ significantly increased. In addition, OsIAA20down-regulation reduced stomatal closure and increased the rate of water loss, while transgenic plants overexpressing OsIAA20 exhibited the opposite physiological responses. Furthermore, an ABA-responsive gene, OsRab21, was down-regulated in OsIAA20 RNAi rice lines and upregulated in OsIAA20 overexpression plants. Those results means OsIAA20 played an important role in plant drought and salt stress responses, by an ABA dependent mechanism, and it will be a candidate target gene used to breed abiotic stress tolerance.

Ambient Ultraviolet B Signal Modulates Tea Flavor Characteristics via Shifting a Metabolic Flux in Flavonoid Biosynthesis.

Tea leaves contain an extraordinarily high level of flavonoids that contribute to tea health benefits and flavor characteristics, but the regulatory mechanism of ambient ultraviolet B (UV-B) on tea flavonoid enrichment remains unclear. Here, we report that ambient UV-B modulates tea quality by inducing a metabolic flux in flavonoid biosynthesis. UV-B absence decreased bitter- and astringent-tasting flavonol glycosides (kaempferol-7-O-glucoside, myricetin-3-O-glucoside, and quercetin-7-O-glucoside) but increased non-galloylated catechins. Conversely, supplementary UV-B increased flavonols and decreased catechins in tea leaves. These responses were achieved via CsHY5, which mediates the UV-B-induced MYB12 activation and binds to the promoters of flavonoid biosynthetic genes (CsFLS, CsLARa, and CsDFRa), leading to flavonoid changes. Transcriptomic data indicated that UV-B-induced tea flavonoid regulation is responsive to multiple biotic and abiotic environmental stresses. These findings improve our understanding of light-regulated tea astringency and bitterness underlying shading effects and seasonal light changes and provide novel insights into tea cultivation management and processing.

XÁC ĐỊNH VÀ PHÂN TÍCH CÁC GENE MÃ HÓA PROTEIN LIÊN KẾT STRESS (SAP) Ở CÂY ĐU ĐỦ (Carica papaya L.) BẰNG PHƯƠNG PHÁP IN SILICO

By using the in silico methods, total of seven stress-associated protein encoding genes have identified in the geneome of papaya (Carica papaya L.). The full-length genomic sequence of papaya SAP genes were ranging from 416 to 813 nucleotides. These genes had single intron or were intronless. The predicted protein sequences included from 114 to 270 amino acids, according to the molecular weight ranged from 13.10 to 29.63 kDa. These proteins were alkaline with a pI value ranging from 8.82 to 9.95. Based on the protein structure and the phylogeneic analysis, the papaya SAP were divided into two groups, I (five members) and II (two members). The papaya SAP had a highly conserved level of structure including two conserved regions, A20-AN21 (group I), or AN21 domains only (group II). RNA-seq analysis showed that all of seven SAP genes expressed in papaya leaves and were induced by freeze thaw awakening treatment (in comparison with control treatment). CpSAP2 showed the highest relative expression level in compared to other SAP genes of papaya. The results of this work have an important significance and are base of the further research on gene cloning, functional analysis of SAP genes and breeding of papaya in response to environmental abiotic stresses.

BiP-overexpressing soybean plants display accelerated hypersensitivity response (HR) affecting the SA-dependent sphingolipid and flavonoid pathways

Biotic and abiotic environmental stresses have limited the increase in soybean productivity. Overexpression of the molecular chaperone BiP in transgenic plants has been associated with the response to osmotic stress and drought tolerance by maintaining cellular homeostasis and delaying hypersensitive cell death. Here, we evaluated the metabolic changes in response to the hypersensitivity response (HR) caused by the non-compatible bacteria Pseudomonas syringae pv. tomato in BiP-overexpressing plants. The HR-modified metabolic profiles in BiP-overexpressing plants were significantly distinct from the wild-type untransformed. The transgenic plants displayed a lower abundance of HR-responsive metabolites as amino acids, sugars, carboxylic acids and signal molecules, including p-aminobenzoic acid (PABA) and dihydrosphingosine (DHS), when compared to infected wild-type plants. In contrast, salicylic acid (SA) biosynthetic and signaling pathways were more stimulated in transgenic plants, and both pathogenesis-related genes (PRs) and transcriptional factors controlling the SA pathway were more induced in the BiP-overexpressing lines. Furthermore, the long-chain bases (LCBs) and ceramide biosynthetic pathways showed alterations in gene expression and metabolite abundance. Thus, as a protective pathway against pathogens, HR regulation by sphingolipids and SA may account at least in part by the enhanced resistance of transgenic plants. GmNAC32 transcriptional factor was more induced in the transgenic plants and it has also been reported to regulate flavonoid synthesis in response to SA. In fact, the BiP-overexpressing plants showed an increase in flavonoids, mainly prenylated isoflavones, as precursors for phytoalexins. Our results indicate that the BiP-mediated acceleration in the hypersensitive response may be a target for metabolic engineering of plant resistance against pathogens.

Potassium Control of Plant Functions: Ecological and Agricultural Implications.

Potassium, mostly as a cation (K+), together with calcium (Ca2+) are the most abundant inorganic chemicals in plant cellular media, but they are rarely discussed. K+ is not a component of molecular or macromolecular plant structures, thus it is more difficult to link it to concrete metabolic pathways than nitrogen or phosphorus. Over the last two decades, many studies have reported on the role of K+ in several physiological functions, including controlling cellular growth and wood formation, xylem–phloem water content and movement, nutrient and metabolite transport, and stress responses. In this paper, we present an overview of contemporary findings associating K+ with various plant functions, emphasizing plant-mediated responses to environmental abiotic and biotic shifts and stresses by controlling transmembrane potentials and water, nutrient, and metabolite transport. These essential roles of K+ account for its high concentrations in the most active plant organs, such as leaves, and are consistent with the increasing number of ecological and agricultural studies that report K+ as a key element in the function and structure of terrestrial ecosystems, crop production, and global food security. We synthesized these roles from an integrated perspective, considering the metabolic and physiological functions of individual plants and their complex roles in terrestrial ecosystem functions and food security within the current context of ongoing global change. Thus, we provide a bridge between studies of K+ at the plant and ecological levels to ultimately claim that K+ should be considered at least at a level similar to N and P in terrestrial ecological studies.

GYMEE: A Global Field-Scale Crop Yield and ET Mapper in Google Earth Engine Based on Landsat, Weather, and Soil Data

In this study, we used Landsat Earth observations and gridded weather data along with global soil datasets available in Google Earth Engine (GEE) to estimate crop yield at 30 m resolution. We implemented a remote sensing and evapotranspiration-based light use efficiency model globally and integrated abiotic environmental stressors (temperature, soil moisture, and vapor deficit stressors). The operational model (Global Yield Mapper in Earth Engine (GYMEE)) was validated against actual yield data for three agricultural schemes with different climatic, soil, and management conditions located in Lebanon, Brazil, and Spain. Field-level crop yield data on wheat, potato, and corn for 2015–2020 were used for assessment. The performance of GYMEE was statistically evaluated through root-mean-square error (RMSE), mean absolute error (MAE), mean bias error (MBE), relative error (RE), and index of agreement (d). The results showed that the absolute difference between the modeled and predicted field-level yield was within ±16% for the analyzed crops in both Brazil and Lebanon study sites and within ±15% in the Spain site (except for two fields). GYMEE performed best for wheat crop in Lebanon with a low RMSE (0.6 t/ha), MAE (0.5 t/ha), MBE (−0.06 t/ha), and RE (0.83%). A very good agreement was observed for all analyzed crop yields, with an index of agreement (d) averaging at 0.8 in all studied sites. GYMEE shows potential in providing yield estimates for potato, wheat, and corn yields at a relative error of ±6%. We also quantified and spatialized the soil moisture stress constraint and its impact on reducing biomass production. A showcasing of moisture stress impact on two emphasized fields from the Lebanon site revealed that a 12% difference in soil moisture stress can decrease yield by 17%. A comparison between the 2017 and 2018 seasons for the potato culture of Lebanon showed that the 2017 season with lower abiotic stresses had higher light use efficiency, above-ground biomass, and yield by 5%, 10%, and 9%, respectively. The results show that the model is of high value for assessing global food production.

Multifaceted Chromatin Structure and Transcription Changes in Plant Stress Response.

Sessile plants are exposed throughout their existence to environmental abiotic and biotic stress factors, such as cold, heat, salinity, drought, dehydration, submergence, waterlogging, and pathogen infection. Chromatin organization affects genome stability, and its dynamics are crucial in plant stress responses. Chromatin dynamics are epigenetically regulated and are required for stress-induced transcriptional regulation or reprogramming. Epigenetic regulators facilitate the phenotypic plasticity of development and the survival and reproduction of plants in unfavorable environments, and they are highly diversified, including histone and DNA modifiers, histone variants, chromatin remodelers, and regulatory non-coding RNAs. They contribute to chromatin modifications, remodeling and dynamics, and constitute a multilayered and multifaceted circuitry for sophisticated and robust epigenetic regulation of plant stress responses. However, this complicated epigenetic regulatory circuitry creates challenges for elucidating the common or differential roles of chromatin modifications for transcriptional regulation or reprogramming in different plant stress responses. Particularly, interacting chromatin modifications and heritable stress memories are difficult to identify in the aspect of chromatin-based epigenetic regulation of transcriptional reprogramming and memory. Therefore, this review discusses the recent updates from the three perspectives—stress specificity or dependence of transcriptional reprogramming, the interplay of chromatin modifications, and transcriptional stress memory in plants. This helps solidify our knowledge on chromatin-based transcriptional reprogramming for plant stress response and memory.

Extramatrical Mycelium and Ectomycorrhizal Community Composition of Quercus pubescens in a Sub-Mediterranean Stress-Prone Environment

Temporal studies that would offer insight into resilience of ectomycorrhizal (ECM) communities in stress prone climates are scarce despite their role in tree nutrition and water supply. Our study characterized the vitality, community composition, diversity, and function of Quercus pubescens Willd. ECM fungi in the Sub-Mediterranean stress-prone environment for 2 consecutive years (June 2016–May 2018) and related the investigated measures to environmental parameters. ECM community was assessed for species actively associating with root tips and exploring the soil volume through the assessment of mycelial ingrowth into sand-filled mesh bags. The investigated period was characterized by a drier than average summer combined with wildfire in 2016 followed by another dry summer in 2017. The vital to non-vital ECM root tip ratio decreased below one in August 2016 and remained low until January 2018. This was ascribed to a series of stress events that occurred at the site including sequential droughts and wildfire. The most abundant ECM lineages on root tips were Tomentella and other Thelephoraceae, Sebacina, and Cenococcum while in mesh bags the most abundant were Tomentella, Sebacina, Pseudotomentella, Pyronemataceae, Inocybe, Cortinarius, Agaricales, and Boletales lineages. High intra-site variability was observed, with ECM communities directly associated with root tips and exploring the soil volume varying significantly among the plots. Community composition was stable over time, while species richness varied with mean air and soil temperature, relative air humidity, and solar radiation. The most abundant exploration type observed at this site was short distance, which was associated with precipitation along with long distance exploration type. The medium distance exploration type was temporally variable and responded to soil temperature and relative air humidity reflecting seasonality at the site. The presented results indicate complex relationships between environmental parameters, abiotic stress, and ECM fungi.

QTL Mapping for Seed Germination Response to Drought Stress in Brassica napus

Drought stress is one of the most environmental abiotic stresses affecting seed germination and crop growth. In the present study, the genetic characteristics of seed germination under drought stress in a Brassica napus double haploid population were analyzed. Five germination-related indexes, including germination percentage (GP), root length (RL), shoot length (SL), fresh weight (FW), and root-to-shoot length ratio (R/S) under control and drought stress, were calculated, and the drought stress index (DSI), including DSI-GP, DSI-RL, DSI-SL, DSI-FW, and DSI-R/S, was determined using the quantitative trait loci (QTLs) analysis based on high-density genetic linkage map. The phenotypic analysis indicated that the R/S is an effective morphological trait in the determination of drought tolerance in the seedling stage. Thirty-nine identified QTLs were observed for these traits and then integrated into 36 consensus QTLs, in which 18 QTLs were found to affect the DSI of four traits (GP, RL, SL, and R/S). Based on the co-linearity between genetic and physical maps of B. napus, 256 candidate genes were detected, and 128 genes have single-nucleotidepolymorphisms/insertion–deletion (SNP/InDel) variations between two parents, some of which were associated with the drought stress tolerance (for example, BnaC03g32780D, BnaC03g37030D, and BnaC09g27300D). The present results laid insights into drought tolerance and its genetic bases in B. napus.

Whole genome sequence of Pantoea agglomerans ANP8, a salinity and drought stress–resistant bacterium isolated from alfalfa (Medicago sativa L.) root nodules

Environmental abiotic stress conditions, especially drought and salinity, are currently the major factors that reduce crop yields worldwide. It has been reported that plant–associated beneficial bacteria, especially strains resistant to abiotic stresses that could maintain their efficiency under environmental challenging conditions, can contribute to alleviate abiotic stresses of host plants. In this study, we presented the assembly of the whole genome of Pantoea agglomerans ANP8, a plant growth-promoting bacterium resistant to salinity and drought stresses. The draft genome assembly contained 4,713,172 bp with 4586 predicted genes. A primary draft genome with a total of 5,115,548 bp and 1916 contigs was obtained (longest contig length being 485,272 bp and smallest contig being 112 bp). Following assembly upgrades, 68 scaffolds and 70 contigs with lengths ≥ 500 bp and an N50 = 209,657 bp were obtained. Number of 5554 and 5472 open reading frames longer than 50 codons were observed in the direct strand and in the reverse strand, respectively. Due to the multiple plant growth-promoting characteristics of this bacterium, genes involved in various indole-3-acetic acid production pathways, e.g., indole-3-pyruvic acid and indole-3-acetamide pathways, were found in the bacterium's genome. In addition, multiple copies of the gcd gene, most important enzymes involvement in the solubilization of phosphates, glucose dehydrogenase, were also observed in this genome. The study provides new genomic information to help understanding the way of action of a stress-tolerant plant growth–promoting bacterium.

GENETIC EVALUATION FOR MORPHOLOGICAL TRAITS OF CORIANDRUM SATIVUM GROWN UNDER SALT STRESS

The Coriandrum is most important among the herb which is used as an ingredient in daily human food. It contains a good amount of antioxidants and health improving ingredients that save human body cells from diseases. It is very sensitive for abiotic environmental stress conditions involving drought, heat, and salt stress as important stress conditions. For this purpose, a study was planned to conduct in the greenhouse of the Institute of Molecular Biology and Biotechnology, University of Lahore to determine the effects of salt stress on Coriandrum seedling growth. For our study we have selected four Coriandrum varieties viz., GAMZE, EAGLE, SUPER XO, and PAK-ORG. The results revealed that there were significant differences among the treatments of NaCl concentrations, Coriandrum genotypes, and the interactions among the Coriandrum genotypes and salt concentrations applied. The average Coriandrum seedling length was recorded as 23.021±1.2026cm while root length was recorded as 22.0128±1.0027cm. The genotype GAMZE showed higher root and shoot length which indicated that GAMZE was a higher salt-tolerant genotype and may be used as a salt-tolerant genotype to improve yield per plant in Coriandrum. The genotype EAGLE has shown poor performance for all of the studied traits which indicated that it was a salt-sensitive Coriandrum genotype. The genetic advance and heritability were found higher for all of the studied traits. The significant correlation between shoot length and root length indicated that the genotypes grow longer roots under stress conditions to increase the shoot length of plants while survive under stressful environmental conditions. The selection of Coriandrum genotype on the basis of root length and shoot length may be useful to improve slat stress tolerance in Coriandrum genotypes for higher seed and green plant biomass yield.

Sorghum rhizosphere effects reduced soil bacterial diversity by recruiting specific bacterial species under low nitrogen stress

Rhizosphere microbiota play a pivotal role in promoting plant growth and defending against pathogens, but their responses to abiotic environmental stress remain largely elusive. Here, we investigated the influences of low-N stress on rhizosphere bacteria of six sorghum cultivars in a glasshouse experiment. The alpha diversity of bacteria (as revealed by Shannon diversity and Chao1 richness indices) was remarkably lower in rhizosphere soils than in bulk soils, and was significantly higher under low-N stress than under N addition. Principal coordinates analysis revealed that the bacterial community compositions in rhizosphere soils were clearly separated from bulk soils, and the rhizosphere soils under low-N stress or with N fertilization were clearly separated, indicating that both rhizosphere effects and N fertilization impacted the rhizosphere bacterial community. Notably, the relative abundances of beneficial bacteria such as Bacillaceae and Streptomycetaceae significantly increased in rhizosphere soils under low-N stress, which had significantly positive correlations with the sorghum N uptake. The relative abundance of Nitrosomonadaceae in rhizosphere soils was significantly lower than that in bulk soils, while the relative abundance of Rhizobiaceae showed an opposite pattern. Taken together, our results suggested that sorghum rhizosphere effects can reduce soil bacterial diversity possibly through recruiting specific bacterial species under low N stress.

Identification, Gene Structure, and Expression of BnMicEmUP: A Gene Upregulated in Embryogenic Brassica napus Microspores.

Microspores of Brassica napus can be diverted from normal pollen development into embryogenesis by treating them with a mild heat shock. As microspore embryogenesis closely resembles zygotic embryogenesis, it is used as model for studying the molecular mechanisms controlling embryo formation. A previous study comparing the transcriptomes of three-day-old sorted embryogenic and pollen-like (non-embryogenic) microspores identified a gene homologous to AT1G74730 of unknown function that was upregulated 8-fold in the embryogenic cells. In the current study, the gene was isolated and sequenced from B. napus and named BnMicEmUP (B. napus microspore embryogenesis upregulated gene). Four forms of BnMicEmUP mRNA and three forms of genomic DNA were identified. BnMicEmUP2,3 was upregulated more than 7-fold by day 3 in embryogenic microspore cultures compared to non-induced cultures. BnMicEmUP1,4 was highly expressed in leaves. Transient expression studies of BnMicEmUP3::GFP fusion protein in Nicotiana benthamiana and in stable Arabidopsis transgenics showed that it accumulates in chloroplasts. The features of the BnMicEmUP protein, which include a chloroplast targeting region, a basic region, and a large region containing 11 complete leucine-rich repeats, suggest that it is similar to a bZIP PEND (plastid envelope DNA-binding protein) protein, a DNA binding protein found in the inner envelope membrane of developing chloroplasts. Here, we report that the BnMicEmUP3 overexpression in Arabidopsis increases the sensitivity of seedlings to exogenous abscisic acid (ABA). The BnMicEmUP proteins appear to be transcription factors that are localized in plastids and are involved in plant responses to biotic and abiotic environmental stresses; as well as the results obtained from this study can be used to improve crop yield.

Application of Brown Algae (Sargassum angustifolium) Extract for Improvement of Drought Tolerance in Canola (Brassica napus L.).

Background: Abiotic environmental stresses, especially drought stress, is one of the most important problems in arid and semi-arid regions. Like other major crops, Brassica napus is vulnerable to drought stress.Objective: The present study was conducted to evaluate efficacy of Sargassum angustifolium extract on mitigating adverse effects of drought stress on B. napus seedlings during vegetative growth under greenhouse conditions.Materials and Methods: Seedlings were periodically sprayed with the seaweed extract until they reached 7-leaf stage. Then water deficit stress was imposed and measurements were performed at morphological, biochemical and molecular levels on three phases: 80% field capacity for 20 days (Phase I), 60% field capacity for 20 days (Phase II) and 40% field capacity for 20 days (Phase III). Real-Time PCR assay was carried out to monitor the changes in expression of the genes involved in proline biosynthesis.Results: Morphological measurements revealed that seaweed treatment improved shoot height and dry weight compared to control (p<0.05). Biochemical analyses indicated that foliar application of seaweed extract significantly enhanced the photosynthetic pigments’ content, free radical scavenging and superoxide dismutase activity (p<0.05). Moreover, proline content was significantly increased in plant tissues treated with seaweed extract (p<0.05). The results of Real-Time PCR assay showed that the increase in proline content is due to enhanced expression of P5CS which is involved in biosynthesis of proline, and to decreased expression of PRODH which catalyzes proline degradation. Conclusions: Overall, the results obtained in this research suggest that application of S. angustifolium extract as a biostimulant is able to protect canola seedlings against deteriorating effects of drought stress.

Comprehensive assessment of Hordeum vulgare in the northern forest-steppe of the Tyumen region

Barley (Hordeum vulgare L.) occupies more than 80% of the sown area of forage crops. Barley is widely cultivated in many areas with contrasting soil and climatic conditions; breeding varieties that are resistant to abiotic and biotic environmental stress factors is an important factor that would make it possible to obtain grain with the required nutritional and forage qualities. The creation of barley varieties is a promising area of breeding in the world. To create varieties, it is necessary to consider the main directions: early ripening and high yield. To create an early ripening, high-yielding variety and hybrid of spring barley with high technological qualities of grain, the leading role belongs to the scientifically grounded selection of the source material. The article presents the results of a 3-year collection samples’ study from the world collection of the All-Russian Institute of Plants’ Genetic Resources named after N.I. Vavilov (VIR).