Search Results (577)

Cytochrome P450 enzymes (CYPs) are crucial catalysts responsible for the oxidative modification of diverse substrates, including plant hormones, antioxidants, and compounds involved in abiotic stress responses. While CYP functions in drought and salt stress adaptation have been extensively studied, their contribution to alkaline stress tolerance, particularly concerning specific cytochrome P450 genes in wild soybean (Glycine soja), remains less explored. In this study, a cytochrome P450 gene, GsCYP93D1, was identified and isolated, and its regulatory role under alkaline stress was elucidated. Transgenic GsCYP93D1 increased Arabidopsis and soybean hairy root resistance to alkaline stress, but the Arabidopsis atcyp93d1 mutant showed a reduced capacity for alkaline tolerance. Subsequent investigation showed the enhanced antioxidant defense capabilities of GsCYP93D1 transgenic plants, as evidenced by reduced superoxide radical (O₂⁻) production under exposure to alkaline stress. Furthermore, compared to the atcyp93d1 mutant, transgenic lines of GsCYP93D1 showed sensitivity to ABA. Moreover, transcript levels of genes associated with alkaline stress response and ABA signaling pathways were elevated in both GsCYP93D1 transgenic and mutant lines. Collectively, our findings demonstrate that GsCYP93D1 positively modulates plant tolerance to alkaline stress and enhances ABA sensitivity. Full article

Climate change has intensified extreme weather events and accelerated soil salinization, posing serious threats to crop yield and quality. Salinity stress, now affecting about 20% of irrigated lands, is expected to worsen due to rising temperatures and sea levels. At the same time, the global population is projected to exceed 9 billion by 2050, demanding a 70% increase in food production (UN, 2019; FAO). Agriculture, responsible for 34% of global greenhouse gas emissions, urgently needs sustainable solutions. Microbial inoculants, known as “plant probiotics,” offer a promising eco-friendly alternative by enhancing crop resilience and reducing environmental impact. In this study, we evaluated the plant growth-promoting (PGP) traits and melatonin-producing capacity of Bacillus aerius EH2-5. To assess its efficacy under salt stress, soybean seedlings at the VC stage were inoculated with EH2-5 and subsequently subjected to salinity stress using 150 mM and 100 mM NaCl treatments. Plant growth parameters, the expression levels of salinity-related genes, and the activities of antioxidant enzymes were measured to determine the microbe’s role in promoting plant growth and mitigating salt-induced oxidative stress. Here, our study shows that the melatonin-synthesizing Bacillus aerius EH2-5 (7.48 ng/mL at 24 h after inoculation in Trp spiked LB media) significantly improved host plant (Glycine max L.) growth, biomass, and photosynthesis and reduced oxidative stress during salinity stress conditions than the non-inculcated control. Whole genome sequencing of Bacillus aerius EH2-5 identified key plant growth-promoting and salinity stress-related genes, including znuA, znuB, znuC, and zur (zinc uptake); ptsN, aspA, and nrgB (nitrogen metabolism); and phoH and pstS (phosphate transport). Genes involved in tryptophan biosynthesis and transport, such as trpA, trpB, trpP, and tspO, along with siderophore-related genes yusV, yfhA, and yfiY, were also detected. The presence of multiple stress-responsive genes, including dnaK, dps, treA, cspB, srkA, and copZ, suggests EH2-5′s genomic potential to enhance plant tolerance to salinity and other abiotic stresses. Inoculation with Bacillus aerius EH2-5 significantly enhanced soybean growth and reduced salt-induced damage, as evidenced by increased shoot biomass (29%, 41%), leaf numbers (12% and 13%), and chlorophyll content (40%, 21%) under 100 mM and 150 mM NaCl compared to non-inoculated plants. These results indicate EH2-5′s strong potential as a plant growth-promoting and salinity stress-alleviating rhizobacterium. The EH2-5 symbiosis significantly enhanced a key ABA biosynthesis enzyme-related gene NCED3, dehydration responsive transcription factors DREB2A and NAC29 salinity stresses (100 mM and 150 mM). Moreover, the reduced expression of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) by 16%, 29%, and 24%, respectively, and decreased levels of malondialdehyde (MDA) and hydroxy peroxidase (H₂O₂) by 12% and 23% were observed under 100 mM NaCl compared to non-inoculated plants. This study demonstrated that Bacillus aerius EH2-5, a melatonin-producing strain, not only functions effectively as a biofertilizer but also alleviates plant stress in a manner comparable to the application of exogenous melatonin. These findings highlight the potential of utilizing melatonin-producing microbes as a viable alternative to chemical treatments. Therefore, further research should focus on enhancing the melatonin biosynthetic capacity of EH2-5, improving its colonization efficiency in plants, and developing synergistic microbial consortia (SynComs) with melatonin-producing capabilities. Such efforts will contribute to the development and field application of EH2-5 as a promising plant biostimulant for sustainable agriculture. Full article

One of the important traits of many plant growth-promoting rhizobacteria (PGPR) is the biocontrol of phytopathogens. Some PGPR metabolize phytohormone abscisic acid (ABA); however, the role of this trait in plant–microbe interactions is scarcely understood. Phytopathogenic fungi produce ABA and use this property as a negative regulator of plant resistance. Therefore, interactions between ABA-producing necrotrophic phytopathogen Botrytis sp. BA3 with ABA-metabolizing rhizobacterium Rhodococcus sp. P1Y were studied in a batch culture and in gnotobiotic hydroponics with sunflower seedlings. Rhizobacterium P1Y possessed no antifungal activity against BA3 and metabolized ABA, which was synthesized by BA3 in vitro and in associations with sunflower plants infected with this fungus. Inoculation with BA3 and the application of exogenous ABA increased the root ABA concentration and inhibited root and shoot growth, suggesting the involvement of this phytohormone in the pathogenesis process. Strain P1Y eliminated negative effects of BA3 and exogenous ABA on root ABA concentration and plant growth. Both microorganisms significantly modulated the hormonal status of plants, affecting indole-3-acetic, salicylic, jasmonic and gibberellic acids, as well as cytokinins concentrations in sunflower roots and/or shoots. The hormonal effects were complex and could be due to the production of phytohormones by microorganisms, changes in ABA concentrations and multiple levels of crosstalk in hormone networks regulating plant defense. The results suggest the counteraction of rhizobacteria to ABA-producing phytopathogenic fungi through the metabolism of fungal ABA. This expands our understanding of the mechanisms related to the biocontrol of phytopathogens by PGPR. Full article

Aflatoxin contamination, primarily caused by Aspergillus flavus, poses a significant threat to peanut (Arachis hypogaea L.) production, food safety, and global trade. Despite extensive efforts, breeding for durable resistance remains difficult due to the polygenic and environmentally sensitive nature of resistance. Although germplasm such as J11 have shown partial resistance, none of the identified lines demonstrated stable or comprehensive protection across diverse environments. Resistance involves physical barriers, biochemical defenses, and suppression of toxin biosynthesis. However, these traits typically exhibit modest effects and are strongly influenced by genotype–environment interactions. A paradigm shift is underway with increasing focus on host susceptibility (S) genes, native peanut genes exploited by A. flavus to facilitate colonization or toxin production. Recent studies have identified promising S gene candidates such as AhS5H1/2, which suppress salicylic acid-mediated defense, and ABR1, a negative regulator of ABA signaling. Disrupting such genes through gene editing holds potential for broad-spectrum resistance. To advance resistance breeding, an integrated pipeline is essential. This includes phenotyping diverse germplasm under stress conditions, mapping resistance loci using QTL and GWAS, and applying multi-omics platforms to identify candidate genes. Functional validation using CRISPR/Cas9, Cas12a, base editors, and prime editing allows precise gene targeting. Validated genes can be introgressed into elite lines through breeding by marker-assisted and genomic selection, accelerating the breeding of aflatoxin-resistant peanut varieties. This review highlights recent advances in peanut aflatoxin resistance research, emphasizing susceptibility gene targeting and genome editing. Integrating conventional breeding with multi-omics and precision biotechnology offers a promising path toward developing aflatoxin-free peanut cultivars. Full article

Low-temperature stress severely limits plant growth and reduces agricultural productivity. Calmodulin-like (CML) proteins are crucial calcium sensors in plant cold responses. Transcriptome analysis of cold-stressed Saussurea involucrata identified seven differentially expressed CML genes. qRT-PCR confirmed that SiCML6 was strongly induced at 4 °C and −2 °C. Bioinformatics analysis showed that SiCML6 encodes a transmembrane protein containing an EF-hand domain. This protein carries a signal peptide and shows the closest phylogenetic relationship to Helianthus annuus CML3. Its promoter contains ABA, methyl jasmonate (MeJA), and cold-response elements. Arabidopsis plants overexpressing SiCML6 showed significantly higher survival rates at −2 °C than wild-type plants. Under freezing stress, SiCML6-overexpressing lines exhibited reduced malondialdehyde content, relative electrolyte leakage, and ROS accumulation (H₂O₂ and O₂⁻), along with increased proline, soluble sugars, soluble proteins, and total antioxidant capacity (T-AOC). SiCML6 elevated the expression of cold-responsive genes CBF3 and COR15a under normal conditions and further upregulated CBF1/2/3 and COR15a at 4 °C. Thus, low temperatures induced SiCML6 expression, which was potentially regulated by ABA/MeJA. SiCML6 enhances freezing tolerance by mitigating oxidative damage through boosted T-AOC and osmoprotectant accumulation while activating the CBF-COR signaling pathway. This gene is a novel target for improving crop cold resistance. Full article

Cinnamomum camphora is an ecologically and economically significant species, highly valued for its essential oil production and environmental benefits. Although a tissue culture system has been established for C. camphora, large-scale propagation remains limited due to the inconsistent formation of adventitious roots (ARs). This study investigated AR formation from callus tissue, focusing on associated physiological changes and gene expression dynamics. During AR induction, contents of soluble sugars and proteins decreased, alongside reduced activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), and polyphenol oxidase (PPO). Levels of indole-3-acetic acid (IAA) and abscisic acid (ABA) decreased significantly throughout AR formation. Zeatin riboside (ZR) levels initially declined and then rose, whereas gibberellic acid (GA) levels displayed the opposite trend. Comparative transcriptomic and temporal expression analyses identified differentially expressed genes (DEGs), which were grouped into four distinct expression patterns. KEGG pathway enrichment indicated that 67 DEGs are involved in plant hormone signaling pathways and that 38 DEGs are involved in the starch and sucrose metabolism pathway. Additionally, protein–protein interaction network (PPI) analysis revealed ten key regulatory genes, which are mainly involved in auxin, cytokinin, GA, ABA, and ethylene signaling pathways. The reliability of the transcriptome data was further validated by quantitative real-time PCR. Overall, this study provides new insights into the physiological and molecular mechanisms underlying AR formation in C. camphora and offers valuable guidance for optimizing tissue culture systems. Full article

The worldwide agriculture industry is facing increasing problems due to rapid population increase and increasingly unfavorable weather patterns. In order to reach the projected food production targets, which are essential for guaranteeing global food security, innovative and sustainable agricultural methods must be adopted. Conventional approaches, including traditional breeding procedures, often cannot handle the complex and simultaneous effects of biotic pressures such as pest infestations, disease attacks, and nutritional imbalances, as well as abiotic stresses including heat, salt, drought, and heavy metal toxicity. Applying phytohormonal approaches, particularly those involving hormonal crosstalk, presents a viable way to increase crop resilience in this context. Abscisic acid (ABA), gibberellins (GAs), auxin, cytokinins, salicylic acid (SA), jasmonic acid (JA), ethylene, and GA are among the plant hormones that control plant stress responses. In order to precisely respond to a range of environmental stimuli, these hormones allow plants to control gene expression, signal transduction, and physiological adaptation through intricate networks of antagonistic and constructive interactions. This review focuses on how the principal hormonal signaling pathways (in particular, ABA-ET, ABA-JA, JA-SA, and ABA-auxin) intricately interact and how they affect the plant stress response. For example, ABA-driven drought tolerance controls immunological responses and stomatal behavior through antagonistic interactions with ET and SA, while using SnRK2 kinases to activate genes that react to stress. Similarly, the transcription factor MYC2 is an essential node in ABA–JA crosstalk and mediates the integration of defense and drought signals. Plants’ complex hormonal crosstalk networks are an example of a precisely calibrated regulatory system that strikes a balance between growth and abiotic stress adaptation. ABA, JA, SA, ethylene, auxin, cytokinin, GA, and BR are examples of central nodes that interact dynamically and context-specifically to modify signal transduction, rewire gene expression, and change physiological outcomes. To engineer stress-resilient crops in the face of shifting environmental challenges, a systems-level view of these pathways is provided by a combination of enrichment analyses and STRING-based interaction mapping. These hormonal interactions are directly related to the United Nations Sustainable Development Goals (SDGs), particularly SDGs 2 (Zero Hunger), 12 (Responsible Consumption and Production), and 13 (Climate Action). This review emphasizes the potential of biotechnologies to use hormone signaling to improve agricultural performance and sustainability by uncovering the molecular foundations of hormonal crosstalk. Increasing our understanding of these pathways presents a strategic opportunity to increase crop resilience, reduce environmental degradation, and secure food systems in the face of increasing climate unpredictability. Full article

Nitrogen use efficiency remains the primary bottleneck for sustainable maize production. This study elucidates the functional mechanisms of the amino acid transporter ZmAAP1 in nitrogen absorption and stress resilience. Through systematic evolutionary analysis of 55 maize inbred lines, we discovered that the ZmAAP1 gene family exhibits distinct chromosomal localization (Chr7 and Chr9) and functional domain diversification (e.g., group 10-specific motifs 11/12), indicating species-specific adaptive evolution. Integrative analysis of promoter cis-elements and multi-omics data confirmed the root-preferential expression of ZmAAP1 under drought stress, mediated via the ABA-DRE signaling pathway. To validate its biological role, we generated transgenic maize lines expressing Arabidopsis thaliana AtAAP1 via Agrobacterium-mediated transformation. Three generations of genetic stability screening confirmed the stable genomic integration and root-specific accumulation of the AtAAP1 protein (Southern blot/Western blot). Field trials demonstrated that low-N conditions enhanced the following transgenic traits: the chlorophyll content increased by 13.5%, and the aboveground biomass improved by 7.2%. Under high-N regimes, the gene-pyramided hybrid ZD958 (AAP1 + AAP1) achieved a 12.3% yield advantage over conventional varieties. Our findings reveal ZmAAP1’s dual role in root development and long-distance nitrogen transport, establishing it as a pivotal target for molecular breeding. This study provides actionable genetic resources for enhancing NUE in maize production systems. Full article

Droughts are predicted to intensify with climate change, posing a serious threat to global crop production. Increasing drought tolerance in plants requires an understanding of the underlying mechanisms. This study measured the physiological, phytohormonal and transcriptomic responses to drought in two apple rootstocks to identify drought ‘biomarkers’ and investigated whether the application of acibenzolar-S-methyl (ASM) to the roots could enhance drought tolerance. Two potted-plant trials were conducted on dwarfing (M9) and semi-dwarfing (CG202) apple rootstocks. In both trials, the response patterns in the roots and leaves were compared between irrigated and non-irrigated plants over a 14-day period. In trial 2, ASM was applied 14 days before and immediately before withdrawing irrigation. Drought induced significant decreases in transpiration, photosynthesis and stomatal conductance in both trials. This was accompanied by the accumulation of abscisic acid (ABA) metabolites and the upregulation of ABA pathway transcripts (CYP707A1/A2 and NCED3), a decrease in 12-oxophytodienoic acid (cis-OPDA) and the downregulation of ABA receptor genes (PYL4). The responses to drought were greater in the roots than the leaves, broadly similar across both rootstocks, but differed in strength and timing between the rootstocks. The application of ASM to the roots did not significantly affect the responsiveness to drought in either rootstock. The identified phytohormonal and transcriptomic biomarkers require further validation across a broader range of genotypes. Full article

Phosphorus deficiency poses a significant challenge to the growth and productivity of crops, particularly in nutrient-poor soils. This study investigates the effects of phosphorus deficiency on the growth, endogenous phytohormones, metabolome, and transcriptome of sweet potato (Ipomoea batatas L.) over a growth period from 30 to 120 days. We found that low phosphorus conditions significantly reduced both above- and below-ground biomass, while tuber number remained unchanged. Endogenous phytohormone analysis revealed altered levels of abscisic acid (ABA), indole-3-acetic acid (IAA), and cytokinins, indicating a complex hormonal response to phosphorus starvation. Transcriptomic analysis identified a total of 6324 differentially expressed genes (DEGs) at 60 days, with significant enrichment in pathways related to stress response and phosphorus utilization (PAPs and PHO1). Metabolomic profiling revealed notable shifts in key metabolites, with consistent downregulation of several phosphorous-related compounds. Our findings highlight the intricate interplay between growth, hormonal regulation, metabolic reprogramming, and gene expression in response to phosphorus deficiency in sweet potato. This research underscores the importance of understanding nutrient stress responses to enhance sweet potato resilience and inform sustainable agricultural practices. Future research should focus on exploring the potential for genetic and agronomic interventions to mitigate the effects of phosphorus deficiency and optimize sweet potato productivity in challenging environments. Full article

Humulus lupulus L. (hop) is a multipurpose crop valued for its essential role in beer production and for its bioactive compounds with recognized medicinal properties. Otherwise, climate change represents a major challenge to agriculture, particularly impacting the cultivation of crops with stenoecious characteristics, such as hop. This highlights the urgent need to enhance crop resilience to adverse environmental conditions. The phytohormone abscisic acid (ABA) is a key regulator of plant responses to abiotic stress, yet the ABA signaling pathway remains poorly characterized in hop. Harnessing the publicly available hop genomics resources, we identified eight members of the PYRABACTIN RESISTANCE 1 LIKE ABA receptor family (HlPYLs). Phylogenetic and gene structure analyses classified these HlPYLs into the three canonical ABA receptor subfamilies. Furthermore, all eight HlPYLs are likely functional, as suggested by the protein sequence visual analysis. Expression profiling indicates that ABA perception in hop is primarily mediated by the HlPYL1-like and HlPYL8-like subfamilies, while the HlPYL4-like group appears to play a more limited role. Structure modeling and topology predictions of HlPYL1b and HlPYL2 provided insights into their potential functional mechanisms. To assess the physiological relevance of ABA signaling in hop, we evaluated the impact of exogenous ABA application during the ex vitro acclimatization phase. ABA-treated plants exhibited more robust growth, reduced stress symptoms, and improved acclimatization success. These effects were associated with reduced leaf transpiration and enhanced stomatal closure, consistent with ABA-mediated drought tolerance mechanisms. Altogether, this study provides the first comprehensive characterization of ABA receptor components in hop and demonstrates the practical utility of ABA in improving plant performance under ex vitro conditions. These findings lay the groundwork for further functional studies and highlight ABA signaling as a promising target for enhancing stress resilience in hop, with broader implications for sustainable agriculture in the face of climate change. Full article

Salt stress is a major constraint to seed germination and early seedling growth in rice, affecting crop establishment and productivity. To understand the mechanisms underlying salt tolerance, we investigated two rice varieties with contrasting responses as follows: salt-tolerant sea rice 86 (SR86) and salt-sensitive P559. Germination assays under increasing NaCl concentrations (50–300 mM) revealed that 100 mM NaCl induced clear phenotypic divergence. SR86 maintained bud growth and showed enhanced root elongation under moderate salinity, while P559 exhibited significant growth inhibition. Transcriptomic profiling of buds and roots under 100 mM NaCl identified over 3724 differentially expressed genes (DEGs), with SR86 showing greater transcriptional plasticity, particularly in roots. Gene ontology enrichment revealed tissue- and genotype-specific responses. Buds showed enrichment in photosynthesis-related and redox-regulating pathways, while roots emphasized ion transport, hormonal signaling, and oxidative stress regulation. SR86 specifically activated genes related to photosystem function, DNA repair, and transmembrane ion transport, while P559 showed activation of oxidative stress-related and abscisic acid (ABA)-regulated pathways. Hormonal profiling supported transcriptomic findings as follows: both varieties showed increased gibberellin 3 (GA3) and gibberellin 4 (GA4) levels under salt stress. SR86 showed elevated auxin (IAA) and reduced jasmonic acid (JA), whereas P559 maintained stable IAA and JA levels. Ethylene precursor and salicylic acid levels declined in both varieties. ABA levels rose slightly but not significantly. These findings suggest that SR86’s superior salt tolerance results from rapid growth, robust transcriptional reprogramming, and coordinated hormonal responses. This study offers key insights into early-stage salt stress adaptation and identifies molecular targets for improving stress resilience in rice. Full article

Drought stress is a predominant abiotic constraint adversely affecting global rice (Oryza sativa) production and threatening food security. While the transcriptional and post-transcriptional regulation of drought-responsive pathways has been widely investigated, the emerging field of epitranscriptomics, particularly RNA chemical modifications such as N6-methyladenosine (m⁶A), adds a new dimension to gene regulation under stress. The most prevalent internal modification in eukaryotic messenger RNA influences RNA metabolism by interacting dynamically with enzymes that add, remove, or recognize the modification. Recent studies in rice reveal that m⁶A deposition is not static but dynamically regulated in response to water-deficit conditions, influencing transcript stability, splicing, nuclear export, and translation efficiency of key drought-responsive genes. This review critically synthesizes current findings on the distribution and functional implications of m⁶A and other epitranscriptomic marks (e.g., 5-methylcytosine [m⁵C], pseudouridine [Ψ]) in modulating rice responses to drought. We discuss the regulatory circuitry involving m⁶A effectors such as OsMTA, OsFIP37, and YTH domain proteins and their integration with known drought-signaling pathways including ABA and reactive oxygen species (ROS) cascades. We also highlight emerging high-resolution technologies such as m⁶A-seq, direct RNA sequencing, and nanopore-based detection that facilitate epitranscriptomic profiling in rice. Finally, we propose future directions for translating epitranscriptomic knowledge into crop improvement, including CRISPR/Cas-based modulation of RNA modification machinery to enhance drought tolerance. Full article

As a beneficial fungus, Trichoderma harzianum (T. harzianum) has been widely applied for growth promotion and biocontrol. Recently, it has attracted much attention with regard to improving stress tolerance in plants under abiotic stress. In this paper, the multiple mechanisms of T. harzianum for alleviating abiotic stress damage in plants are reviewed. T. harzianum can regulate the synthesis of key phytohormones, such as abscisic acid (ABA), indole-3-acetic acid (IAA), etc., thereby enhancing the physiological response ability of plants under stress conditions such as drought, salt stress, and high temperature. These are associated with antioxidant system regulation in plants, which reduces levels of reactive oxygen species (ROS) and oxidative damage and maintains intracellular redox balance. T. harzianum can also improve plant nutrient uptake and root development, secondary metabolism, soil environment and structure, and expression of related genes. In addition, in this paper, the characteristics of T. harzianum application in field and horticultural crops are summarized and compared, revealing differences in the methods, concentrations, time, and effects of applying T. harzianum to various crops. We further explore the synergistic regulation effect of T. harzianum and plant–microbiome interaction on the stress microenvironment. Future perspectives on the molecular mechanism of T. harzianum and its field application potential are discussed. This review provides a theoretic and practical reference for the application of T. harzianum in agricultural production. Full article

Pinus elliottii, a key economic conifer in southern China, requires efficient propagation methods to meet demand for elite germplasm in resin and timber production. While somatic embryogenesis-based plant regeneration has been successfully achieved in Pinus elliottii, large-scale production remains challenging. Our results demonstrate that the genotype of Pinus elliottii significantly influences the induction rate of embryogenic callus. During somatic embryo maturation, the liquid–solid induction method increased the number of mature embryos by 25.85 times. Maturation efficiency was further enhanced by a 3-week pretreatment followed by the application of 9 mg/L ABA, 0.5 mg/L PSK, and 6 mg/L COS. Additionally, the incorporation of activated carbon significantly promoted both the maturation and germination of somatic embryos. In the somatic embryo maturation stage, 1 g/L activated carbon induced 288.67 mature embryos per gram of embryogenic callus, resulting in a total of 1452 embryos. During germination, the application of 4 g/L activated carbon achieved a germination rate of 63%, and the survival rate of somatic embryo-derived seedlings reached 85%. This study not only identifies the optimal conditions for somatic embryogenesis in Pinus elliottii but also establishes an efficient protocol for somatic embryo maturation induction, providing a crucial scientific foundation for the rapid propagation and seedling production of Pinus elliottii. Full article