Abiotic Stress Conditions Research Articles

Comprehensive Investigation of Cucumber Heat Shock Proteins under Abiotic Stress Conditions: A Multi-Omics Survey.

Heat-shock proteins (Hsps) are a family of proteins essential in preserving the vitality and functionality of proteins under stress conditions. Cucumber (Cucumis sativus) is a widely grown plant with high nutritional value and is used as a model organism in many studies. This study employed a genomics, transcriptomics, and metabolomics approach to investigate cucumbers' Hsps against abiotic stress conditions. Bioinformatics methods were used to identify six Hsp families in the cucumber genome and to characterize family members. Transcriptomics data from the Sequence Read Archive (SRA) database was also conducted to select CsHsp genes for further study. Real-time PCR was used to evaluate gene expression levels under different stress conditions, revealing that CssHsp-08 was a vital gene for resistance to stress conditions; including drought, salinity, cold, heat stresses, and ABA application. Gas Chromatography-Mass Spectrometry (GC-MS) analysis of plant extracts revealed that amino acids accumulate in leaves under high temperatures and roots under drought, while sucrose accumulates in both tissues under applied most stress factors. The study provides valuable insights into the structure, organization, evolution, and expression profiles of the Hsp family and contributes to a better understanding of plant stress mechanisms. These findings have important implications for developing crops that can withstand environmental stress conditions better.

Biochemical Basis of Abiotic Stress Tolerance in Native Isolates of <i>Beauveria bassiana</i> (Balsamo) Vuillemin from Kerala

A study on the screening of Beauveria bassiana (Balsamo) Vuillemin native isolates for abiotic stress tolerance was carried out at the Department of Agricultural Entomology, College of Agriculture, Vellanikkara, Thrissur, Kerala during 2019-2023. The growth and biochemical parameters of the three native isolates of B. bassiana (BTL1: OP271760, BTL2: OP290199 and PKDE: OP292066) were studied under different abiotic stress conditions viz., temperature, water stress, acidity and salinity. The results revealed that the highest temperature tolerance (40° C) was displayed by the B. bassiana isolate PKDE. It also survived at high water stress (45% polyethylene glycol), acidic (pH2) and saline (1.5 M) conditions. The analysis of biochemical parameters in stress tolerant isolate revealed that the greatest levels of trehalose (2.033± 0.025, 2.043± 0.006 mg/ min/ g of mycelia), catalase (0.0072± 0.007, 0.0032± 0.003 EU/ min/ mg protein) and peroxidase (0.0602± 0.005, 0.0175± 0.017 EU/ min/ mg tissue weight) were observed after exposure to high temperature and water stress, respectively. This shows that exposure to abioticstress and biochemical parameters are closely related and can be used as determinants for evaluating the potential of biocontrol agents.

Heat shock factor binding protein BrHSBP1 regulates seed and pod development in Brassica rapa.

Plant heat shock factor binding proteins (HSBPs) are well known for their implication in the negative regulation of heat stress response (HSR) pathways. Herein, we report on the hitherto unknown functions of HSBP1 in Brassica rapa (BrHSBP1). BrHBSP1 was found to be predominant in flower buds and young leaves, while its segmental duplicate, BrHSBP1-like, was abundant in green siliques. Exposure to abiotic stress conditions, such as heat, drought, cold, and H2O2, and to phytohormones was found to differentially regulate BrHSBP1. The activity of BrHSBP1-GFP fusion proteins revealed their cellular localization in nuclei and cytosols. Transgenic overexpression of BrHSBP1 (BrHSBP1OX) improved pod and seed sizes, while CRISPR-Cas BrHSBP1 knock-out mutants (Brhsbp1_KO) were associated with aborted seed and pod development. The transcriptomic signatures of BrHSBP1OX and Brhsbp1_KO lines revealed that 360 and 2381 genes, respectively, were differentially expressed (Log2FC≥2, padj<0.05) expressed relative to control lines. In particular, developmental processes, including plant reproductive structure development (RSD)-related genes, were relatively downregulated in Brhsbp1_KO. Furthermore, yeast two-hybrid assays confirmed that BrHSBP1 can physically bind to RSD and other genes. Taking the findings together, it is clear that BrHSBP1 is involved in seed development via the modulation of RSD genes. Our findings represent the addition of a new regulatory player in seed and pod development in B. rapa.

Role of Arbuscular Mycorrhizal Fungi in Regulating Growth, Enhancing Productivity, and Potentially Influencing Ecosystems under Abiotic and Biotic Stresses.

Arbuscular mycorrhizal fungi (AMF) form symbiotic relationships with the roots of nearly all land-dwelling plants, increasing growth and productivity, especially during abiotic stress. AMF improves plant development by improving nutrient acquisition, such as phosphorus, water, and mineral uptake. AMF improves plant tolerance and resilience to abiotic stressors such as drought, salt, and heavy metal toxicity. These benefits come from the arbuscular mycorrhizal interface, which lets fungal and plant partners exchange nutrients, signalling molecules, and protective chemical compounds. Plants' antioxidant defence systems, osmotic adjustment, and hormone regulation are also affected by AMF infestation. These responses promote plant performance, photosynthetic efficiency, and biomass production in abiotic stress conditions. As a result of its positive effects on soil structure, nutrient cycling, and carbon sequestration, AMF contributes to the maintenance of resilient ecosystems. The effects of AMFs on plant growth and ecological stability are species- and environment-specific. AMF's growth-regulating, productivity-enhancing role in abiotic stress alleviation under abiotic stress is reviewed. More research is needed to understand the molecular mechanisms that drive AMF-plant interactions and their responses to abiotic stresses. AMF triggers plants' morphological, physiological, and molecular responses to abiotic stress. Water and nutrient acquisition, plant development, and abiotic stress tolerance are improved by arbuscular mycorrhizal symbiosis. In plants, AMF colonization modulates antioxidant defense mechanisms, osmotic adjustment, and hormonal regulation. These responses promote plant performance, photosynthetic efficiency, and biomass production in abiotic stress circumstances. AMF-mediated effects are also enhanced by essential oils (EOs), superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), hydrogen peroxide (H2O2), malondialdehyde (MDA), and phosphorus (P). Understanding how AMF increases plant adaptation and reduces abiotic stress will help sustain agriculture, ecosystem management, and climate change mitigation. Arbuscular mycorrhizal fungi (AMF) have gained prominence in agriculture due to their multifaceted roles in promoting plant health and productivity. This review delves into how AMF influences plant growth and nutrient absorption, especially under challenging environmental conditions. We further explore the extent to which AMF bolsters plant resilience and growth during stress.

Investigation of the expansin gene family in sugar beet (Beta vulgaris) by the genome-wide level and their expression responses under abiotic stresses.

Sugar beet (Beta vulgaris ssp. vulgaris) is primarily used in sugar production worldwide. Expansins are a gene family of cell wall proteins effective in regulating cell wall structure. They also participate in developmental stages, including cell and leaf growth, root development, and fruit ripening. This study comprehensively characterizes the expansin gene family members found in the sugar beet genome. In addition, in silico expression analysis of sugar beet expansin genes under variable abiotic stress conditions and expression profiles of expansin genes under combined drought and heat stresses by the qRT-PCR method were evaluated in the study. A total of 31 sugar beet expansin genes were identified. BvuEXLA-02 and BvuEXLB-02 genes can have abiotic stress tolerance roles besides their roles in normal development. Determining the properties of sugar beet expansin, family members can help enable the cellulose hydrolysis mechanism and raise plant biomass. Elucidating expression profiles of the sugar beet expansin genes under variable stress conditions can support improving plant productivity. The results of the current study may also contribute to the deep understanding of sugar beet expansin genes in the future.

Nutrient management: as a panacea to improve the caryopsis quality and yield potential of durum wheat (Triticum turgidum L.) under the changing climatic conditions.

The increasing human population and the changing climate, which have given rise to frequent drought spells, pose a serious threat to global food security, while identification of high-yielding drought-tolerant genotypes coupled with nutrient management remains a proficient approach to cope with these challenges. An increase in seasonal temperature, recurring drought stress, and elevated atmospheric CO2 are alarmingly affecting durum wheat production, productivity, grain quality, and the human systems it supports. An increase in atmospheric carbon dioxide can improve wheat grain yield in a certain amount, but the right amount of nutrients, water, and other required conditions should be met to realize this benefit. Nutrients including nitrogen, silicon, and sulfur supply could alleviate the adverse effects of abiotic stress by enhancing antioxidant defense and improving nitrogen assimilation, although the effects on plant tolerance to drought stress varied with nitrogen ionic forms. The application of sewage sludge to durum wheat also positively impacts its drought stress tolerance by triggering high accumulation of osmoregulators, improving water retention capacity in the soil, and promoting root growth. These beneficial effect of nutrients contribute to durum wheat ability to withstand and recover from abiotic stress conditions, ultimately enhance its productivity and resilience. While these nutrients can provide benefits when applied in appropriate amounts, their excessive use can lead to adverse environmental consequences. Advanced technologies such as precision nutrient management, unmanned aerial vehicle-based spraying, and anaerobic digestion play significant roles in reducing the negative effects associated with nutrients like sewage sludge, zinc, nanoparticles and silicon fertilizers. Hence, nutrient management practices offer significant potential to enhance the caryopsis quality and yield potential of durum wheat. Through implementing tailored nutrient management strategies, farmers, breeders, and agronomists can contribute to sustainable durum wheat production, ensuring food security and maintaining the economic viability of the crop under the changing climatic conditions.

Genome-wide identification of Apetala2 gene family in Hypericum perforatum L and expression profiles in response to different abiotic and hormonal treatments.

We identified 21 AP2 TFs in H. perforatum using bioinformatic methods; their physical and chemical properties, gene structures, conserved motifs, evolutionary relationships, cis-acting elements, and expression patterns were investigated. We found that based on the structural characteristics and evolutionary relationships, the HpAP2 gene family can be divided into three subclasses: euANT, baselANT, and euAP2. A canonical HpAP2 TF shared a conserved protein structure, while a unique motif 6 was found in HpAP2_1, HpAP2_4, and HpAP2_5 from the euANT subgroup, indicating potential biological and regulatory functions of these genes. Furthermore, a total of 59 cis-acting elements were identified, most of which were associated with growth, development, and resistance to stress in plants. Transcriptomics data showed that 57.14% of the genes in the AP2 family were differentially expressed in four organs. For example, HpAP2_18 was specifically expressed in roots and stems, whereas HpAP2_17 and HpAP2_11 were specifically expressed in leaves and flowers, respectively. HpAP2_5, HpAP2_11, and HpAP2_18 showed tissue-specific expression patterns and responded positively to hormones and abiotic stresses. These results demonstrated that the HpAP2 family genes are involved in diverse developmental processes and generate responses to abiotic stress conditions in H. perforatum. This article, for the first time, reports the identification and expression profiles of the AP2 family genes in H. perforatum, laying the foundation for future functional studies with these genes.

Genome-wide analysis of the SMXL gene family in common bean and identification of karrikin-responsive PvSMXL2 as a negative regulator of PEG-induced drought stress

Common bean (Phaseolus vulgaris L.) is a major legume crop worldwide, but its growth and development frequently face challenges due to abiotic stresses, particularly drought. Proper supplement of copper could mitigate the adverse effects of drought, but excessive accumulation of this metal in plants can be harmful. The suppressor of MAX2 1-like (SMXL) gene family, which plays important roles in various plant processes, including stress responses, remains poorly understood in common bean. In this study, we identified nine orthologues of SMXL genes in common bean, which are located on six chromosomes and classified into four subgroups. Basic molecular properties, including theoretical isoelectric point (PI), molecular weight (MW), grand average of hydropathicity (GVIO), gene structure, and conserved motifs were characterized, and numerous cis-elements in promoters were predicted. The expression patterns of PvSMXL genes were found to be distinct under 10% polyethylene glycol (PEG)-induced drought stress and 200 μM Cu treatments. Most PvSMXLs showed reduced expression in response to Cu treatment, whereas nearly half PvSMXLs exhibited inducible expression under drought stress. PvSMXL2, which exhibited a rapid response to karrikin 1 (KAR1), an active form of the plant growth regulators newly found in the smoke of burning plant material, was down-regulated by both PEG-induced drought and Cu stresses. Transient silencing of PvSMXL2 resulted in enhanced drought stress tolerance without conferring Cu tolerance. These findings provide valuable insights into the functions of SMXL genes in common bean under abiotic stress conditions.

Pyramiding of transcription factor, PgHSF4, and stress-responsive genes of p68, Pg47, and PsAKR1 impart multiple abiotic stress tolerance in rice (Oryza sativa L.).

Abiotic stresses such as drought, salinity, and heat stress significantly affect rice crop growth and production. Under uncertain climatic conditions, the concurrent multiple abiotic stresses at different stages of rice production became a major challenge for agriculture. Hence, improving rice's multiple abiotic stress tolerance is essential to overcome unprecedented challenges under adverse environmental conditions. A significant challenge for rice breeding programs in improving abiotic stress tolerance involves multiple traits and their complexity. Multiple traits must be targeted to improve multiple stress tolerance in rice and uncover the mechanisms. With this hypothesis, in the present study gene stacking approach is used to integrate multiple traits involved in stress tolerance. The multigene transgenics co-expressing Pennisetum glaucum 47 (Pg47), Pea 68 (p68), Pennisetum glaucum Heat Shock Factor 4(PgHSF4), and Pseudomonas Aldo Keto Reductase 1 (PsAKR1) genes in the rice genotype (AC39020) were developed using the in-planta transformation method. The promising transgenic lines maintained higher yields under semi-irrigated aerobic cultivation (moisture stress). These 15 promising transgenic rice seedlings showed improved shoot and root growth traits under salinity, accelerating aging, temperature, and oxidative stress. They showed better physiological characteristics, such as chlorophyll content, membrane stability, and lower accumulation of reactive oxygen species, under multiple abiotic stresses than wild-type. Enhanced expression of transgenes and other stress-responsive downstream genes such as HSP70, SOD, APX, SOS, PP2C, and P5CS in transgenic lines suggest the possible molecular mechanism for imparting the abiotic stress tolerance. This study proved that multiple genes stacking as a novel strategy induce several mechanisms and responsible traits to overcome multiple abiotic stresses. This multigene combination can potentially improve tolerance to multiple abiotic stress conditions and pave the way for developing climate-resilient crops.

Bacillus subtilis ER-08, a multifunctional plant growth-promoting rhizobacterium, promotes the growth of fenugreek (Trigonella foenum-graecum L.) plants under salt and drought stress.

Sustainable agriculture and meeting the world's food needs face considerable obstacles from abiotic stresses such as soil salinity and drought. This critical issue was addressed by our current study, which sought to uncover multi-trait bioinoculants from hostile ecosystems that could help mitigate salinity and drought stresses at the same time. The Bacillus subtilis ER-08 (BST) strain was isolated from the halotolerant plant Fagonia cretica which was collected from the Little Rann of Kachchh, India. Various biochemical and molecular approaches were applied for the detailed characterization of the BST isolate. The BST isolate demonstrated notable plant growth-promoting qualities. Fenugreek seed biopriming was performed using the BST isolate. The effect of BST seed treatment on fenugreek developmental indices as well as abiotic alleviation was examined under greenhouse conditions. The BST produced 83.7 g ml-1 gibberellins (GA3) and 176.1 g ml-1 indole-3 acetic acid. Moreover, hydrogen cyanide, siderophore, exopolysaccharides (EPS), ammonia, cellulase, protease, pectinase, and chitinase were also produced by the BST strain. Interestingly, 52% of Fusarium oxysporum mycelial growth was suppressed by the BST isolate under in vitro conditions. Furthermore, BST isolates functioned well under several abiotic stress conditions, for instance, salinity (4 and 6 ds m-1), pH (5, 7, and 9), drought (PEG6000 at 10%, 20%, and 30%), and temperature (25°C, 35°C, 37°C, and 55°C). This study indicates that the BST strain might serve as an effective bio-inoculant for minimizing the detrimental effects of abiotic stresses.

When drought meets heat - a plant omics perspective.

Changes in weather patterns with emerging drought risks and rising global temperature are widespread and negatively affect crop growth and productivity. In nature, plants are simultaneously exposed to multiple biotic and abiotic stresses, but most studies focus on individual stress conditions. However, the simultaneous occurrence of different stresses impacts plant growth and development differently than a single stress. Plants sense the different stress combinations in the same or in different tissues, which could induce specific systemic signalling and acclimation responses; impacting different stress-responsive transcripts, protein abundance and modifications, and metabolites. This mini-review focuses on the combination of drought and heat, two abiotic stress conditions that often occur together. Recent omics studies indicate common or independent regulators involved in heat or drought stress responses. Here, we summarize the current research results, highlight gaps in our knowledge, and flag potential future focus areas.

Genome-wide characterization of the role of the KCS gene family in Allium fistulosum L. as regulators of abiotic stress responses

Cuticle wax is a defensive coating on the surfaces of plant tissues that helps shield them from both biotic and abiotic stressors. The 3-ketoacyl-CoA synthase (KCS) enzymes control the rate-limiting step in the synthesis of very-long-chain fatty acids (VLCFAs), thereby regulating wax biosynthesis. In the present study, a genome-wide approach was used to identify 31 members of the KCS gene family in Allium fistulosum that were classified into 9 groups through phylogenetic analysis. These genes were unevenly distributed throughout the A. fistulosum genome, and 7 (AfKCS1, AfKCS2, AfKCS4, AfKCS13, AfKCS17, AfKCS24, and AfKCS28) of them did not harbor any introns. Cis-acting regulatory element analysis revealed that all of these genes were associated with at least one hormone- or stress-responsive element, and heatmap analysis of the expression patterns of these AfKCS genes revealed that they were primarily expressed in the stems and leaf sheaths of A. fistulosum. Eight of these AfKCS genes that were highly expressed in leaf tissue samples harvested from A. fistulosum were further analyzed to detect changes in their expression in response to salt, drought, and low or high temperature stress exposure. All 8 were significantly upregulated in response to salt, low temperature, and high temperature stress, while 4 (AfKCS14, AfKCS15, AfKCS23, AfKCS26) were downregulated in response to drought stress, offering potentially valuable insight into the roles that they play in the context of abiotic stress resistance. Together these findings offer a new foundation for future analysis of the importance of members of the KCS gene family in A. fistulosum play under conditions of abiotic stress and other physiological settings.

Impact of Exogenous Melatonin Application on Photosynthetic Machinery under Abiotic Stress Conditions.

Inhospitable conditions that hinder plant growth and development encompass a range of abiotic stresses, such as drought, extreme temperatures (both low and high), salinity, exposure to heavy metals, and irradiation. The cumulative impact of these stresses leads to a considerable reduction in agricultural productivity worldwide. The generation of reactive oxygen species (ROS) is a shared mechanism of toxicity induced by all these abiotic stimuli in plants, resulting in oxidative damage and membrane instability. Extensive research has shed light on the dual role of melatonin in plants, where it serves as both a growth regulator, fostering growth and development, and a potent protector against abiotic stresses. The inherent potential of melatonin to function as a natural antioxidant positions it as a promising biostimulant for agricultural use, bolstering plants' abilities to withstand a wide array of environmental challenges. Beyond its antioxidant properties, melatonin has demonstrated its capacity to regulate the expression of genes associated with the photosynthetic process. This additional characteristic enhances its appeal as a versatile chemical agent that can be exogenously applied to plants, particularly in adverse conditions, to improve their resilience and optimize photosynthetic efficiency in every phase of the plant life cycle. An examination of the molecular mechanisms underlying the stress-protective effects of exogenous melatonin on the photosynthetic machinery of plants under various abiotic stresses is presented in this paper. In addition, future prospects are discussed for developing stress-tolerant crops for sustainable agriculture in challenging environments.

Efficacy of biofertilizers in different stress management of fruit crops- A Review

Biofertilizers are gaining widespread acceptance in agriculture due to their numerous advantages over chemical fertilizers. These environmentally friendly alternatives play a crucial role in enhancing soil health and fertility through various mechanisms. Biofertilizers consist of diverse microorganisms that can effectively promote plant growth and development, even under abiotic stress conditions. As a result, the utilization of biofertilizers is steadily increasing, especially with the escalating costs of chemical fertilizers and their adverse effects on soil health and crop yields. Certain microorganisms, such as Azotobacter, Azospirillum, Arbuscular Mycorrhizal Fungi (AMF) Gigaspora rosea, Pseudomonas, and Funneliformis geosporus, hold substantial potential for commercial use as biofertilizers to improve the growth and development of fruit crops. In-depth research has demonstrated that biofertilizers can significantly augment the biomass and productivity of various fruit crops. Their application in fruit crop production is particularly beneficial as they not only enhance growth but also confer improved resistance to abiotic stress factors like high temperatures, drought, salinity, and metal toxicity. This comprehensive review highlights the substantial promise of biofertilizers in mitigating abiotic stress and fostering sustainable practices in fruit crop cultivation.

Evaluation of secondary sexual dimorphism of the dioecious Amaranthus palmeri under abiotic stress

The evolution of secondary sex-specific traits of dioecious species under abiotic stress conditions has received limited research, especially in the case of Amaranthus palmeri, a fast adapting and highly competing plant. Here, we have examined the interactive effects of abiotic stress on mineral accumulation, chlorophyll a and b content, and the operating capacity of Photosystem II (PSII) in both male and female A. palmeri plants grown under three different intensities of white light, and under N, K or P deficiency. Mineral profiling of the leaves and stems (with inflorescence) highlighted intra- and intersexual differences in their accumulation pattern and mineral associations. Chlorophyll a and chlorophyll b were different between the male and the female plants, being slightly lower in the latter, at high light intensity towards maturity, or under K or P deficiency. Further, slight, although statistically significant differences were recorded in the chlorophyll a/b ratio, which was lower at the higher light intensity in the female, over that in the male, plants towards maturity. Chlorophyll fluorescence parameters, i.e., steady state and maximum fluorescence increased under high light intensity, whereas the PSII operating efficiency decreased in the female plants, indicating reduced PSII capacity. Sex-specific differences in A. palmeri showed a differential response to stressful conditions because of differences in their ontogeny and physiology, and possibly due to the cost of reproduction. We suggest that the breeding system of dioecious species has weaknesses that can be used for the ecological management of dioecious weeds without relying on the use of herbicides.

Endophytic Bacillus strains enhance biomass and bioactive metabolites of Gloriosa superba

Gloriosa superba L. is an economically important medicinal plant and variation in its colchicine content may be due to associated endo- and ectophytic beneficial microbes. Among them, endophytic bacteria contribute to enhancing plant growth, induce biotic and abiotic stress tolerance, and play a significant role in secondary metabolite synthesis. In the present study, 76 native endophytic bacteria were isolated from high and low-colchicine and gloriosine-containing chemotypes of G. superba rhizome and characterized for vegetative growth enhancement and abiotic stress mitigation. The screening has resulted in the selection of 23 plant growth-promoting (PGP) bacterial endophytes with abiotic stress tolerance. Most of these isolates belong to the Bacillus genera identification based on the 16S rRNA gene. Based on the significant enhancement in maize (Zea mays L.; as model host plant) under greenhouse conditions ten efficient bacterial strains were selected. Further, three endophytic bacterial strains, NBRI HYL5 and NBRI HYL8 (high colchicine and gloriosine containing chemotype), and NBRI LYN9 (low colchicine and gloriosine containing chemotype) were selected based on the survivability and enhanced 1-aminocyclopropane-1- carboxylate (ACC) deaminase activity, phosphate solubilization, biofilm, Indole acidic acid (IAA), exopolysaccharide, and alginate production abilities under different abiotic stress conditions. Finally, a greenhouse experiment was conducted to evaluate the effect of selected bacterial endophyte inoculation in G. superba for growth enhancement and secondary metabolite content. The results showed that plants treated with NBRI HYL5 and NBRI HYL8 significantly enhanced the colchicine content (97–98 %) and gloriosine content (70–73 %), respectively as compared with control. However, inoculation of NBRI LYN9 has demonstrated significant enhancement only in gloriosine content (79 %). In addition, NBRI HYL5 and NBRI HYL8 have demonstrated significant improvement in overall vegetative growth parameters, photosynthetic pigments, and total soluble sugar content. Colonization and persistence of selected endophytic bacteria in G. superba rhizome and shoot clearly depicted the involvement not only in enhancing the vegetative growth but also in enhancing the colchicine and gloriosine content. Overall, this study presents the beneficial role of endophytic Bacillus strains in enhancing the growth of G. superba and secondary metabolite content may lead to contribute in sustainable cultivation of economically important medicinal plants.

BRI1 EMS SUPPRESSOR1 genes regulate abiotic stress and anther development in wheat (Triticum aestivum L.).

BRI1 EMS SUPPRESSOR1 (BES1) family members are crucial downstream regulators that positively mediate brassinosteroid signaling, playing vital roles in the regulation of plant stress responses and anther development in Arabidopsis. Importantly, the expression profiles of wheat (Triticum aestivum L.) BES1 genes have not been analyzed comprehensively and systematically in response to abiotic stress or during anther development. In this study, we identified 23 BES1-like genes in common wheat, which were unevenly distributed on 17 out of 21 wheat chromosomes. Phylogenetic analysis clustered the BES1 genes into four major clades; moreover, TaBES1-3A2, TaBES1-3B2 and TaBES1-3D2 belonged to the same clade as Arabidopsis BES1/BZR1 HOMOLOG3 (BEH3) and BEH4, which participate in anther development. The expression levels of 23 wheat BES1 genes were assessed using real-time quantitative PCR under various abiotic stress conditions (drought, salt, heat, and cold), and we found that most TaBES1-like genes were downregulated under abiotic stress, particularly during drought stress. We therefore used drought-tolerant and drought-sensitive wheat cultivars to explore TaBES1 expression patterns under drought stress. TaBES1-3B2 and TaBES1-3D2 expression was high in drought-tolerant cultivars but substantially repressed in drought-sensitive cultivars, while TaBES1-6D presented an opposite pattern. Among genes preferentially expressed in anthers, TaBES1-3B2 and TaBES1-3D2 expression was substantially downregulated in thermosensitive genic male-sterile wheat lines compared to common wheat cultivar under sterile conditions, while we detected no obvious differences under fertile conditions. This result suggests that TaBES1-3B2 and TaBES1-3D2 might not only play roles in regulating drought tolerance, but also participate in low temperature-induced male sterility.

Phyto-microbiome to mitigate abiotic stress in crop plants.

Plant-associated microbes include taxonomically diverse communities of bacteria, archaebacteria, fungi, and viruses, which establish integral ecological relationships with the host plant and constitute the phyto-microbiome. The phyto-microbiome not only contributes in normal growth and development of plants but also plays a vital role in the maintenance of plant homeostasis during abiotic stress conditions. Owing to its immense metabolic potential, the phyto-microbiome provides the host plant with the capability to mitigate the abiotic stress through various mechanisms like production of antioxidants, plant growth hormones, bioactive compounds, detoxification of harmful chemicals and toxins, sequestration of reactive oxygen species and other free radicals. A deeper understanding of the structure and functions of the phyto-microbiome and the complex mechanisms of phyto-microbiome mediated abiotic stress mitigation would enable its utilization for abiotic stress alleviation of crop plants and development of stress-resistant crops. This review aims at exploring the potential of phyto-microbiome to alleviate drought, heat, salinity and heavy metal stress in crop plants and finding sustainable solutions to enhance the agricultural productivity. The mechanistic insights into the role of phytomicrobiome in imparting abiotic stress tolerance to plants have been summarized, that would be helpful in the development of novel bioinoculants. The high-throughput modern approaches involving candidate gene identification and target gene modification such as genomics, metagenomics, transcriptomics, metabolomics, and phyto-microbiome based genetic engineering have been discussed in wake of the ever-increasing demand of climate resilient crop plants.

Linking the role of melatonin in plant stress acclimatization

Melatonin is a derivative of tryptophan and consists of a conserved domain present ubiquitously from bacteria to higher organisms. Melatonin is an emerging pleiotropic plant growth hormone that is pivotal in coping with various biotic and abiotic stress conditions. It regulates downstream signaling transduction that modulates plants' physiological and biochemical pathways. Melatonin can be externally applied and could strengthen the stress tolerance mechanism of plants by enhancing ROS-scavenging enzymatic and non-enzymatic antioxidant defense systems. Which consequently exhibits lower lipid peroxidation, MDA content, greater enzyme activity, metabolic pool, ion homeostasis, and plasma membrane integrity under stress conditions. In addition, melatonin protects photosynthetic machinery by maintaining cell membrane stability and chlorophyll recovery. It also stimulates the electron transport chain during photosynthesis and D1 protein biosynthesis and maximizes the photochemistry efficiency (Fv/Fm) of photosystem II and photochemical quenching. Besides abiotic stress, melatonin plays a significant role in biotic stress tolerance. This review emphasizes Melatonin as a stress protectant under biotic and abiotic stress. Further, we have highlighted integrating advanced biotechnology tools with recent information for the possible application of melatonin in the current scenario of changing climate.

Genome-wide identification of KCS gene family in Carya illinoinensis and their roles under abiotic stress conditions

Pecan (Carya illinoinensis) is an important economic tree species of genus Carya in the Juglandaceae. Its nuts are rich in nutrients, becoming one of the consumer's favorite ones. The pecan production is facing serious threats from drought, soil salinization and acidification. β-Keto-acyl-CoA synthase (KCS) is an important enzyme responsible for the formation of very long chain fatty acid (VLCFA) and its derivatives. However, the characteristic of CiKCS genes family in pecan and their function under abiotic stress remain greatly unknown. Here, 30 CiKCSs were identified and distributed in the 14 chromosomes, subjected to gene duplication and strong purification selection. The cis-regulatory elements in the 2 kb promoters of these CiKCSs mainly correlated with plant growth, development and stress response. Notably, CiKCS3/4/5/6/24/28 genes expressions were significantly up-regulated under drought, salt and acid stresses. Interestingly, the expression of CiKCS12 under acid stress were down-regulated. CiKCS3/5/6/12 were further shown to be mainly located in the cytoplasm, had no self-activation activity and could not interact with each other. Heterologous expression of these four genes improved VLCFA levels in tobacco and mediated the tolerance of yeast to osmotic, salt, and acid treatments. These results preliminarily suggested that CiKCS3/5/6/12 might function in the cytoplasm through monomeric forms and improve the tolerance of pecan to abiotic stress mainly by mediating VLCFA synthesis. These findings will deepen the understanding of the characteristic and function of CiKCS genes, and provide new direction and reference for the stress-resistant breeding of pecan.