Abiotic Stress Tolerance In Plants Research Articles

Photosynthetic machinery and antioxidant enzymes system regulation confers cadmium stress tolerance to tomato seedlings pretreated with melatonin

Cadmium (Cd), a significant heavy metal, is widely distributed in the Earth's crust. However, little is known about its effects on plants and management measured. Melatonin (MEL) is a well-known multifunctional biomolecule; it is a powerful antioxidant molecule that increases a plant's abiotic stress tolerance. MEL enhances nickel, vanadium, and chromium tolerance in plants. This research aimed to examine the impact of Cd-stress on tomato plants and explore the possible contribution of MEL in improving the resistance of tomato plants towards Cd-stress. The current findings exhibited that MEL application significantly enhanced leaf photosynthesis, root structure, osmolytes accumulation, and seedling growth compared with only Cd treatment. MEL application decreased Cd transport from root to shoot, lowering Cd concentrations in leaves. In addition, MEL treatment increased catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR) activity and decreased the level of hydrogen peroxide (H2O2), superoxide ion (O2·−) and malondialdehyde (MDA) in tomato plants. Considering findings, MEL may be used to increase plant growth and Cd stress tolerance while lowering the availability of Cd to plants.

Vitis Myb14 confer cold and drought tolerance by activating lipid transfer protein genes expression and reactive oxygen species scavenge

The R2R3 Myb transcription factor exhibits a wide range of functions and participates in various biological processes in plant development, secondary metabolism, and abiotic stress tolerance, among others. Vitis Myb14 initially identified for its involvement in resveratrol synthesis in grapevines. In this study, we investigate its role in abiotic stress tolerance. Significant differences in expression were observed between two grape varieties, Vitis amurensis (Cold-hardy) and V. vinifera (Cold-sentitive), under abiotic and hormone treatments. Both VvMyb14 and VaMyb14 demonstrated responsiveness to cold, drought and high salt treatment, but VaMyb14 exhibited a quicker and more pronounced response. To investigate further, we overexpressed VaMyb14 in A. thalina and found that VaMyb14 OE plants showed significantly enhanced cold and drought tolerance compared to wild-type plants. Additionally, the transgenic lines exhibited increased antioxidant enzyme activity, particularly POD activity, and reduced MDA content. Microarray analysis of VaMyb14 OE plants revealed up-regulation of several ABA metabolism and signal transduction genes, including several LTPs, PP2Cs, RD29B, COR78 and other structural genes, indicating that VaMyb14 has the capacity to reprogram a significant signaling pathway. Furthermore, comparative mRNA sequencing profiling of 35S:VaMyb14 grapevine callus indicated its involvement its function involved in ROS scavenging and ABA signaling. These findings collectively demonstrate that Vitis Myb14 serves as a critical regulator in grapevine stress responses, contributing to improved defense against necrotrophic pathogens, enhanced phytoalexin resveratrol production, and increased drought or cold tolerance.

Examining the Transcriptomic and Biochemical Signatures of Bacillus subtilis Strains: Impacts on Plant Growth and Abiotic Stress Tolerance.

Rhizobacteria from various ecological niches display variations in physiological characteristics. This study investigates the transcriptome profiling of two Bacillus subtilis strains, BsCP1 and BsPG1, each isolated from distinct environments. Gene expression linked to the synthesis of seven types of antibiotic compounds was detected in both BsCP1 and BsPG1 cultures. Among these, the genes associated with plipastatin synthesis were predominantly expressed in both bacterial strains. However, genes responsible for the synthesis of polyketide, subtilosin, and surfactin showed distinct transcriptional patterns. Additionally, genes involved in producing exopolysaccharides (EPS) showed higher expression levels in BsPG1 than in BsCP1. Consistently with this, a greater quantity of EPS was found in the BsPG1 culture compared to BsCP1. Both bacterial strains exhibited similar effects on Arabidopsis seedlings, promoting root branching and increasing seedling fresh weight. However, BsPG1 was a more potent enhancer of drought, heat, and copper stress tolerance than BsCP1. Treatment with BsPG1 had a greater impact on improving survival rates, increasing starch accumulation, and stabilizing chlorophyll content during the post-stress stage. qPCR analysis was used to measure transcriptional changes in Arabidopsis seedlings in response to BsCP1 and BsPG1 treatment. The results show that both bacterial strains had a similar impact on the expression of genes involved in the salicylic acid (SA) and jasmonic acid (JA) signaling pathways. Likewise, genes associated with stress response, root development, and disease resistance showed comparable responses to both bacterial strains. However, treatment with BsCP1 and BsPG1 induced distinct activation of genes associated with the ABA signaling pathway. The results of this study demonstrate that bacterial strains from different ecological environments have varying abilities to produce beneficial metabolites for plant growth. Apart from the SA and JA signaling pathways, ABA signaling triggered by PGPR bacterial strains could play a crucial role in building an effective resistance to various abiotic stresses in the plants they colonize.

A pervasive phosphorylation cascade modulation of plant transcription factors in response to abiotic stress.

Transcriptional regulation of stress-responsive genes is a crucial step in establishing the mechanisms behind plant abiotic stress tolerance. A sensitive method of regulating transcription factors activity, stability, protein interaction, and subcellular localization is through phosphorylation. This review highlights a widespread regulation mechanism that involves phosphorylation of plant TFs in response to abiotic stress. Abiotic stress is one of the main components limiting crop yield and sustainability on a global scale. It greatly reduces the land area that is planted and lowers crop production globally. In all living organisms, transcription factors (TFs) play a crucial role in regulating gene expression. They participate in cell signaling, cell cycle, development, and plant stress response. Plant resilience to diverse abiotic stressors is largely influenced by TFs. Transcription factors modulate gene expression by binding to their target gene's cis-elements, which are impacted by genomic characteristics, DNA structure, and TF interconnections. In this review, we focus onthe six major TFs implicated in abiotic stress tolerance, namely, DREB, bZIP, WRKY, ABF, MYB, and NAC, and the cruciality of phosphorylation of these transcription factors in abiotic stress signaling, as protein phosphorylation has emerged as one of the key post-translational modifications, playing a critical role in cell signaling, DNA amplification, gene expression and differentiation, and modification of other biological configurations. These TFs have been discovered after extensive study as stress-responsive transcription factors which may be major targets for crop development and important contributors to stress tolerance and crop production.

Genome-Wide Identification and Expression Analysis of RLCK-VII Subfamily Genes Reveal Their Roles in Stress Responses of Upland Cotton.

Receptor-like cytoplasmic kinase VII (RLCK-VII) subfamily members are vital players in plant innate immunity and are also involved in plant development and abiotic stress tolerance. As a widely cultivated textile crop, upland cotton (Gossypium hirsutum) attaches great importance to the cotton industry worldwide. To obtain details of the composition, phylogeny, and putative function of RLCK-VII genes in upland cotton, genome-wide identification, evolutionary event analysis, and expression pattern examination of RLCK-VII subfamily genes in G. hirsutum were performed. There are 129 RLCK-VII members in upland cotton (GhRLCKs) and they were divided into nine groups based on their phylogenetic relationships. The gene structure and sequence features are relatively conserved within each group, which were divided based on their phylogenetic relationships, and consistent with those in Arabidopsis. The phylogenetic analysis results showed that RLCK-VII subfamily genes evolved in plants before the speciation of Arabidopsis and cotton, and segmental duplication was the major factor that caused the expansion of GhRLCKs. The diverse expression patterns of GhRLCKs in response to abiotic stresses (temperature, salt, and drought) and V. dahliae infection were observed. The candidates that may be involved in cotton's response to these stresses are highlighted. GhRLCK7 (GhRLCK7A and D), which is notably induced by V. dahliae infection, was demonstrated to positively regulate cotton defense against V. dahliae by the loss-of-function assay in cotton. These findings shed light on the details of the RLCK-VII subfamily in cotton and provide a scaffold for the further function elucidation and application of GhRLCKs for the germplasm innovation of cotton.

Uncovering the mechanisms of salicylic acid-mediated abiotic stress tolerance in horticultural crops.

Salicylic acid (SA) has been recognized as a promising molecule for improving abiotic stress tolerance in plants due to its ability to enhance antioxidant defense system, and promote root architecture system. Recent research has focused on uncovering the mechanisms by which SA confers abiotic stress tolerance in horticultural crops. SA has been shown to act as a signaling molecule that triggers various physiological and morphological responses in plants. SA regulates the production of reactive oxygen species (ROS). Moreover, it can also act as signaling molecule that regulate the expression of stress-responsive genes. SA can directly interact with various hormones, proteins and enzymes involved in abiotic stress tolerance. SA regulates the antioxidant enzymes activities that scavenge toxic ROS, thereby reducing oxidative damage in plants. SA can also activate protein kinases that phosphorylate and activate transcription factors involved in stress responses. Understanding these mechanisms is essential for developing effective strategies to improve crop resilience in the face of changing environmental conditions. Current information provides valuable insights for farmers and plant researchers, offering new strategies to enhance crop resilience and productivity in the face of environmental challenges. By harnessing the power of SA and its signaling pathways, farmers can develop more effective stress management techniques and optimize crop performance. Plant researchers can also explore innovative approaches to breed or engineer crops with enhanced stress tolerance, thereby contributing to sustainable agriculture and food security.

Modulation of potassium transport to increase abiotic stress tolerance in plants.

Potassium is the major cation responsible for the maintenance of the ionic environment in plant cells. Stable potassium homeostasis is indispensable for virtually all cellular functions, and, concomitantly, viability. Plants must cope with environmental changes such as salt or drought that can alter ionic homeostasis. Potassium fluxes are required to regulate the essential process of transpiration, so a constraint on potassium transport may also affect the plant's response to heat, cold, or oxidative stress. Sequencing data and functional analyses have defined the potassium channels and transporters present in the genomes of different species, so we know most of the proteins directly participating in potassium homeostasis. The still unanswered questions are how these proteins are regulated and the nature of potential cross-talk with other signaling pathways controlling growth, development, and stress responses. As we gain knowledge regarding the molecular mechanisms underlying regulation of potassium homeostasis in plants, we can take advantage of this information to increase the efficiency of potassium transport and generate plants with enhanced tolerance to abiotic stress through genetic engineering or new breeding techniques. Here, we review current knowledge of how modifying genes related to potassium homeostasis in plants affect abiotic stress tolerance at the whole plant level.

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.

Comprehensive genome-wide analysis of the DREB gene family in Moso bamboo (Phyllostachys edulis): evidence for the role of PeDREB28 in plant abiotic stress response.

Dehydration response element binding (DREB) proteins are vital for plant abiotic stress responses, but the understanding of DREBs in bamboo, an important sustainable non-timber forest product, is limited. Here we conducted a comprehensive genome-wide analysis of the DREB gene family in Moso bamboo, representing the most important running bamboo species in Asia. In total, 44 PeDREBs were identified, and information on their gene structures, protein motifs, phylogenetic relationships, and stress-related cis-regulatory elements (CREs) was provided. Based on the bioinformatical analysis, we further analyzed PeDREBs from the A5 group and found that four of five PeDREB transcripts were induced by salt, drought, and cold stresses, and their proteins could bind to stress-related CREs. Among these, PeDREB28 was selected as a promising candidate for further functional characterization. PeDREB28 is localized in nucleus, has transcriptional activation activity, and could bind to the DRE- and coupling element 1- (CE1) CREs. Overexpression of PeDREB28 in Arabidopsis and bamboo improved plant abiotic stress tolerance. Transcriptomic analysis showed that broad changes due to the overexpression of PeDREB28. Furthermore, 628 genes that may act as the direct PeDREB28 downstream genes were identified by combining DAP-seq and RNA-seq analysis. Moreover, we confirmed that PeDREB28 could bind to the promoter of pyrabactin-resistance-like gene (DlaPYL3), which is a homolog of abscisic acid receptor in Arabidopsis, and activates its expression. In summary, our study provides important insights into the DREB gene family in Moso bamboo, and contributes to their functional verification and genetic engineering applications in the future.

Calcium (Ca2+ ) sensors and MYC2 are crucial players during jasmonates-mediated abiotic stress tolerance in plants.

Plants evolve stress-specific responses that sense changes in their external environmental conditions and develop various mechanisms for acclimatization and survival. Calcium (Ca2+ ) is an essential stress-sensing secondary messenger in plants. Ca2+ sensors, including calcium-dependent protein kinases (CDPKs), calmodulins (CaMs), CaM-like proteins (CMLs), and calcineurin B-like proteins (CBLs), are involved in jasmonates (JAs) signaling and biosynthesis. Moreover, JAs are phospholipid-derived phytohormones that control plant response to abiotic stresses. The JAs signaling pathway affects hormone-receptor gene transcription by binding to the basic helix-loop-helix (bHLH) transcription factor. MYC2 acts as a master regulator of JAs signaling module assimilated through genes. Ca2+ sensor CML regulates MYC2 and is involved in a distinct mechanism mediating JAs signaling during abiotic stresses. This review highlights the pivotal role of the Ca2+ sensors in JAs biosynthesis and MYC2-mediated JAs signaling during abiotic stresses in plants.

Screening of endophytic Bacteria from stress-tolerating plants for abiotic stress tolerance and plant growth-promoting properties: Identification of potential strains for bioremediation and crop enhancement

Enhancing plant productivity and fortifying defense mechanisms against biotic and abiotic stresses is crucial for sustainable agriculture. To achieve this, researchers have investigated the use of endophytic bacteria as a viable alternative to chemical fertilizers and pesticides. In this study, 50 endophytic microbes were isolated from stress-tolerant parts of different plants, including Lantana camara, Phoenix dactylifera, Hemerocallis fulva, Salvia rosmarinus, Commiphora wightii, and Abutilon indicum. These microbes were evaluated for their tolerance to abiotic stresses and ability to promote plant growth. Among the isolates, R1L2 and A2L2L2 exhibited the highest tolerance to salt stress, withstanding up to 16% NaCl. DL2R2, R1L2, and A1S1S were the most tolerant to lead stress, tolerating up to 6% w/v lead. For cadmium stress, R1L2, DL3R2, and DP1L1L1 showed the highest tolerance, enduring up to 6% w/v cadmium. The isolates were also assessed for their plant growth-promoting (PGP) activities, including the production of IAA, Gibberellin, Cytokinin, HCN, siderophore, phosphate solubilization, and nitrogen fixation. All isolates were positive for nitrogen fixation attribute. However, under specific stress conditions, all isolates showed negative results for HCN production, siderophore production, or inorganic phosphate solubilization. Isolates A1S1S and DL3R2 demonstrated positive results for producing phytohormones such as IAA, Gibberellin, and Cytokinin. Through phenotypic and biochemical characteristics, as well as 16S rDNA gene sequencing, isolate A1S1S was identified as Pelomonas aquatic (accession no. OP984335), and isolate DL3R2 was identified as Solibacillus silvestris (accession no. OP854919). These findings suggest that the endophytic strains Pelomonas aquatic and Solibacillus silvestris have potential applications as multi-stress reducers, bioremediation agents, and crop growth promoters in essential crops.

Suggesting a prospect for melatonin-mediated orchid flowering under extreme conditions

Abiotic stress is a major constraint in the successful growth and development of ornamental plants under severe conditions. Since antiquity, melatonin homeostasis has been an effective contrivance in the strategies of abiotic stress tolerance in plants, although it is completely neglected in orchids, the champagne of flowers. Orchids with exceptionally long vegetative phase face a number of stresses and, therefore, stress alleviation has been a hot topic in orchid cultivation. The in-vitro flowering is a useful method for early identification of hybrids in crop improvement programs. We successfully achieved in-vitro leafless flowering in three Cymbidium orchids (C. sinense, C. goeringii and C. ensifolium), which are elite flowers in terms of versatile flower shapes, esthetic preference and price. Transcriptomic analysis was performed to compare the leafless flowers with leaves to identify genes related to tryptophan pathway and melatonin biosynthesis. More than 50 differentially expressed genes (DEGs) were identified in each species with contrasting expressions in the leafless flowers and leaves. The important melatonin pathway genes included serotonin N-acetyltransferase (SNAT), caffeic acid 3-O-methyltransferase (CAMT) and tryptophan decarboxylase (TDC). Moreover, clustering analysis pointed out the significant abiotic stress tolerance-related genes. This opening report, thus, provides a robust cradle to idealize the melatonin as an effective abiotic stress regulator to aid the long journey of vegetative growth and then flowering in precious orchids.

Recent Developments in CRISPR/Cas9 Genome-Editing Technology Related to Plant Disease Resistance and Abiotic Stress Tolerance.

The revolutionary CRISPR/Cas9 genome-editing technology has emerged as a powerful tool for plant improvement, offering unprecedented precision and efficiency in making targeted gene modifications. This powerful and practical approach to genome editing offers tremendous opportunities for crop improvement, surpassing the capabilities of conventional breeding techniques. This article provides an overview of recent advancements and challenges associated with the application of CRISPR/Cas9 in plant improvement. The potential of CRISPR/Cas9 in terms of developing crops with enhanced resistance to biotic and abiotic stresses is highlighted, with examples of genes edited to confer disease resistance, drought tolerance, salt tolerance, and cold tolerance. Here, we also discuss the importance of off-target effects and the efforts made to mitigate them, including the use of shorter single-guide RNAs and dual Cas9 nickases. Furthermore, alternative delivery methods, such as protein- and RNA-based approaches, are explored, and they could potentially avoid the integration of foreign DNA into the plant genome, thus alleviating concerns related to genetically modified organisms (GMOs). We emphasize the significance of CRISPR/Cas9 in accelerating crop breeding processes, reducing editing time and costs, and enabling the introduction of desired traits at the nucleotide level. As the field of genome editing continues to evolve, it is anticipated that CRISPR/Cas9 will remain a prominent tool for crop improvement, disease resistance, and adaptation to challenging environmental conditions.

OsRuvBL1a DNA helicase boost salinity and drought tolerance in transgenic indica rice raised by in planta transformation

RuvBL, is a member of SF6 superfamily of helicases and is conserved among the various model systems. Recently, rice (Oryza sativa L.) homolog of RuvBL has been biochemically characterized for its ATPase and DNA helicase activities; however its involvement in stress has not been studied so far. Present investigation reports the detailed functional characterization of OsRuvBL under abiotic stresses through genetic engineering. An efficient Agrobacterium-mediated in planta transformation protocol was developed in indica rice to generate the transgenic lines and study was focused on optimization of factors to achieve maximum transformation efficiency. Overexpressing OsRuvBL1a transgenic lines showed enhanced tolerance under in vivo salinity stress as compared to WT plants. The physiological and biochemical analysis of the OsRuvBL1a transgenic lines showed better performance under salinity and drought stresses. Several stress responsive interacting partners of OsRuvBL1a were identified using Y2H system revealed to its role in stress tolerance. Functional mechanism for boosting stress tolerance by OsRuvBL1a has been proposed in this study. This integration of OsRuvBL1a gene in rice genome using in planta transformation method helped to achieve the abiotic stress resilient smart crop. This study is the first direct evidence to show the novel function of RuvBL in boosting abiotic stress tolerance in plants.

Signaling and crosstalk of rhizobacterial and plant hormones that mediate abiotic stress tolerance in plants.

Agricultural areas exhibiting numerous abiotic stressors, such as elevated water stress, temperatures, and salinity, have grown as a result of climate change. As such, abiotic stresses are some of the most pressing issues in contemporary agricultural production. Understanding plant responses to abiotic stressors is important for global food security, climate change adaptation, and improving crop resilience for sustainable agriculture, Over the decades, explorations have been made concerning plant tolerance to these environmental stresses. Plant growth-promoting rhizobacteria (PGPR) and their phytohormones are some of the players involved in developing resistance to abiotic stress in plants. Several studies have investigated the part of phytohormones in the ability of plants to withstand and adapt to non-living environmental factors, but very few have focused on rhizobacterial hormonal signaling and crosstalk that mediate abiotic stress tolerance in plants. The main objective of this review is to evaluate the functions of PGPR phytohormones in plant abiotic stress tolerance and outline the current research on rhizobacterial hormonal communication and crosstalk that govern plant abiotic stress responses. The review also includes the gene networks and regulation under diverse abiotic stressors. The review is important for understanding plant responses to abiotic stresses using PGPR phytohormones and hormonal signaling. It is envisaged that PGPR offer a useful approach to increasing plant tolerance to various abiotic stresses. However, further studies can reveal the unclear patterns of hormonal interactions between plants and rhizobacteria that mediate abiotic stress tolerance.

Research Progress in Soybean by Phytohormone Modulation and Metal Chelation over the Past Decade

Phytohormones have been acknowledged as an eco-friendly and alternative source for plant growth promotion and abiotic stress tolerance. Heavy metal stress has attained considerable attention worldwide because of its serious effects. Globally, it is a major cause of crop yield loss. Soybean is an important legume crop that continuously faces environmental stress, such as heavy metal stress. The application of plant growth regulators, such as phytohormones, enhances plant tolerance toward heavy metals. Phytohormones augment the interaction with plants. They improve plant productivity under stress due to the potential of phytostabilization. They are capable of enhancing metal stress tolerance by reducing oxidation stress. In the present review, an attempt has been made to summarize the role of phytohormones in metal chelation in a model plant, soybean. The results suggest that among the phytohormones, ABA, JA, SA ET, GA, and IAA are synergistic with metal chelation, whereas cytokinins are antagonistic. The application of phytohormones and corresponding microbes enhances the production of glutathione (GSH), which enhances metal tolerance by metal sequestration.

Systematic Analysis of Galactinol Synthase and Raffinose Synthase Gene Families in Potato and Their Expression Patterns in Development and Abiotic Stress Responses.

Raffinose family oligosaccharides (RFOs) are very important for plant growth, development, and abiotic stress tolerance. Galactinol synthase (GolS) and raffinose synthase (RFS) are critical enzymes involved in RFO biosynthesis. However, the whole-genome identification and stress responses of their coding genes in potato remain unexplored. In this study, four StGolS and nine StRFS genes were identified and classified into three and five subgroups, respectively. Remarkably, a total of two StGolS and four StRFS genes in potato were identified to form collinear pairs with those in both Arabidopsis and tomato, respectively. Subsequent analysis revealed that StGolS4 exhibited significantly high expression levels in transport-related tissues, PEG-6000, and ABA treatments, with remarkable upregulation under salt stress. Additionally, StRFS5 showed similar responses to StGolS4, but StRFS4 and StRFS8 gene expression increased significantly under salt treatment and decreased in PEG-6000 and ABA treatments. Overall, these results lay a foundation for further research on the functional characteristics and molecular mechanisms of these two gene families in response to ABA, salt, and drought stresses, and provide a theoretical foundation and new gene resources for the abiotic-stress-tolerant breeding of potato.

MdMPK3 and MdMPK6 fine-tune MdWRKY17-mediated transcriptional activation of the melatonin biosynthesis gene MdASMT7.

Melatonin (N-acetyl-5-methoxytryptamine) is a potent reactive oxygen species (ROS) scavenger that increases the biotic and abiotic stress tolerance in plants. The signaling and regulation pathways of melatonin in plants remain elusive. Here, we report that transgenic apple (Malus domestica) plants overexpressing the transcription factor gene, MdWRKY17, have higher melatonin contents and lower ROS levels than those of control, while the MdWRKY17 RNA interference (RNAi) lines show the reversed phenotype. The binding of MdWRKY17 to N-acetylserotonin O-methyltransferase7 (MdASMT7) directly promotes the MdASMT7 expression in the in vitro and in vivo. MdASMT7is a melatonin synthase that localizes to the plasma membrane. MdASMT7 overexpression rescued the lower melatonin contents of MdWRKY17-RNAi lines, confirming the role of MdWRKY17-MdASMT7 module in melatonin biosynthesis in apple. Furthermore, melatonin treatment activated the mitogen-activated kinases (MPKs) MdMPK3 and MdMPK6, which phosphorylate MdWRKY17 to promote transcriptional activation of MdASMT7. RNAi-mediated silencing of MdMPK3/6 decreases MdASMT7 expression in transgenic apple plants overexpressing MdWRKY17, which further confirms MdMPK3/6 fine-tunes MdWRKY17-mediated MdASMT7 transcription. This also forms a positive loop that melatonin activates MdMPK3/6 and thus accelerates the biosynthesis of itself via triggering MdMPK3/6-MdWRKY17-MdASMT7 pathway. This novel melatonin regulatory pathway not only have dissected the molecular mechanisms of melatonin biosynthesis but also provided an alternative approach for generating transgenic melatonin-rich apples which may benefits to human health.

Multi-Omics Pipeline and Omics-Integration Approach to Decipher Plant's Abiotic Stress Tolerance Responses.

The present day's ongoing global warming and climate change adversely affect plants through imposing environmental (abiotic) stresses and disease pressure. The major abiotic factors such as drought, heat, cold, salinity, etc., hamper a plant's innate growth and development, resulting in reduced yield and quality, with the possibility of undesired traits. In the 21st century, the advent of high-throughput sequencing tools, state-of-the-art biotechnological techniques and bioinformatic analyzing pipelines led to the easy characterization of plant traits for abiotic stress response and tolerance mechanisms by applying the 'omics' toolbox. Panomics pipeline including genomics, transcriptomics, proteomics, metabolomics, epigenomics, proteogenomics, interactomics, ionomics, phenomics, etc., have become very handy nowadays. This is important to produce climate-smart future crops with a proper understanding of the molecular mechanisms of abiotic stress responses by the plant's genes, transcripts, proteins, epigenome, cellular metabolic circuits and resultant phenotype. Instead of mono-omics, two or more (hence 'multi-omics') integrated-omics approaches can decipher the plant's abiotic stress tolerance response very well. Multi-omics-characterized plants can be used as potent genetic resources to incorporate into the future breeding program. For the practical utility of crop improvement, multi-omics approaches for particular abiotic stress tolerance can be combined with genome-assisted breeding (GAB) by being pyramided with improved crop yield, food quality and associated agronomic traits and can open a new era of omics-assisted breeding. Thus, multi-omics pipelines together are able to decipher molecular processes, biomarkers, targets for genetic engineering, regulatory networks and precision agriculture solutions for a crop's variable abiotic stress tolerance to ensure food security under changing environmental circumstances.

Alleviation of Shade Stress in Chinese Yew (Taxus chinensis) Seedlings with 5-Aminolevulinic Acid (ALA).

5-aminolevulinic acid (ALA) is a novel regulator that can promote plant growth, nitrogen uptake, and abiotic stress tolerance. Its underlying mechanisms, however, have not been fully investigated. In this study, the effects of ALA on morphology, photosynthesis, antioxidant systems, and secondary metabolites in two cultivars of 5-year-old Chinese yew (Taxus chinensis) seedlings, 'Taihang' and 'Fujian', were examined under shade stress (30% light for 30 days) using different doses of ALA (0, 30, and 60 mg/L). The findings from our study show that shade stress significantly reduced plant height, stem thickness, and crown width and increased malondialdehyde (MDA) levels. However, the application of 30 mg/L ALA effectively mitigated these effects, which further induced the activity of antioxidant enzymes under shade stress, resulting in the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) being increased by 10%, 16.4%, and 42.1%, and 19.8%, 20.1%, and 42% in 'Taihang' and 'Fujian', respectively. It also promoted their role in the absorption, conversion, and efficient use of light energy. Additionally, the use of 30 mg/L ALA caused a significant increase in the concentration of secondary metabolites, including polysaccharide (PC), carotenoid (CR), and flavonoids (FA), with increases of up to 46.1%, 13.4%, and 35.6% and 33.5%, 7.5%, and 57.5% in both yew cultivars, respectively, contributing to nutrient uptake. With ALA treatment, the yew seedlings showed higher chlorophyll (total chlorophyll, chlorophyll a and b) levels and photosynthesis rates than the seedlings that received the shade treatment alone. To conclude, the application of 30 mg/L ALA alleviated shade stress in yew seedlings by maintaining redox balance, protecting the photorespiratory system, and increasing organic metabolites, thus increasing the number of new branches and shoots and significantly promoting the growth of the seedlings. Spraying with ALA may be a sustainable strategy to improve the shade-resistant defense system of yew. As these findings increase our understanding of this shade stress response, they may have considerable implications for the domestication and cultivation of yew.