SlSNAT1-dependent melatonin synthesis enhances tomato cold tolerance by promoting SlNCED1-mediated ABA accumulation, thereby strengthening antioxidant capacity, maintaining photosynthesis, and reducing ROS-induced membrane damage under cold stress. Cold stress limits greenhouse tomato growth by suppressing photosynthesis, promoting reactive oxygen species (ROS) accumulation, and disrupting membrane integrity, which ultimately reduces yield. Melatonin (MT) enhances plant stress tolerance, but its role in regulating cold adaptation in tomato remains unclear. Here, we used CRISPR/Cas9-generated SlSNAT1 mutants and VIGS-mediated SlNCED1-silenced plants to test how MT influences abscisic acid (ABA) biosynthesis and cold tolerance. The SlSNAT1 mutation markedly reduced endogenous MT, decreased the expression of ABA biosynthetic genes (SlNCED1/2), and increased the expression of ABA catabolic genes (SlCYP707A1/2), thereby weakening cold-induced ABA accumulation. Accordingly, the mutants showed higher membrane permeability and ROS levels, together with lower photosynthetic efficiency and reduced antioxidant enzyme activity under cold stress. SlNCED1 silencing further reduced ABA accumulation and antioxidant capacity. By contrast, exogenous MT partly restored ABA content, antioxidant enzyme activity, and photosynthetic performance, thereby alleviating cold injury. Correlation analysis showed that ABA content was positively associated with antioxidant activity, photosynthetic traits, and osmotic regulators, but negatively associated with ROS levels and membrane damage. MT synthesis mediated by SlSNAT1 promotes ABA accumulation, at least in part, by enhancing SlNCED1 expression. These findings clarify a mechanism underlying MT-ABA cross talk during cold stress and suggest a potential strategy to enhance cold tolerance in greenhouse tomato.

Micro-nano ethylene bubbles water promotes anthocyanin accumulation in grapes by regulating endogenous ethylene and synergistic abscisic acid.

Boron fortifies a dual barrier in rice roots: How Casparian strip reinforcement and cell wall remodeling restrict cadmium entry.

Dendrobium officinale, a valuable medicinal plant, is highly susceptible to cold stress, which particularly affects the accumulation of secondary metabolites. Abscisic acid (ABA) is a key hormone regulating plant responses to cold stress; however, the physiological and molecular mechanisms underlying exogenous ABA-mediated cold tolerance in D. officinale remain largely unknown. In this study, we investigated the effects of exogenous ABA application under cold stress on physiological and biochemical traits, gene expression profiles, and the accumulation of major medicinal components in D. officinale seedlings. At the physiological and biochemical level, exogenous ABA treatment significantly increased biomass accumulation and relative water content (RWC) in D. officinale under cold stress. It also elevated endogenous ABA levels, reduced stomatal conductance, and thereby enhanced water retention capacity. Compared with cold stress alone, plants subjected to combined ABA and cold treatments exhibited significantly lower malondialdehyde (MDA) content and electrolyte leakage, indicating reduced membrane lipid peroxidation. In addition, proline accumulation was promoted and chlorophyll degradation was alleviated. At the molecular level, transcriptomic analysis revealed the differential expression of multiple cold-responsive genes (e.g., DREB1, SKIP30, AP2-3, APRR9, Ubc12) as well as key genes involved in ABA biosynthesis and signaling pathways (e.g., NCED1, NCED2, PP2C50, SnRK1, PYR1-2). Furthermore, both cold stress and exogenous ABA treatment significantly modulated the expression of genes associated with polysaccharide and alkaloid biosynthesis, thereby promoting the accumulation of these medicinal compounds. Exogenous ABA application effectively alleviates cold stress-induced growth inhibition in D. officinale by enhancing endogenous ABA accumulation and inducing stomatal closure. Moreover, ABA treatment mitigates cold-induced membrane damage and regulates osmotic adjustment through the modulation of compatible solutes and secondary metabolites. These findings provide new insights into ABA-mediated signal transduction under cold stress and offer a theoretical basis for the development of cold-tolerant D. officinale cultivars.

Drought poses a significant global challenge to agriculture, substantially reducing crop yields. Abscisic acid (ABA) plays a crucial role in response to drought stress. Nevertheless, the molecular mechanism underlying the ABA-mediated drought stress response in apple remains poorly understood. We identified a drought- and ABA-induced AP2/ERF transcription factor (TF), MhSHINE2-like, which positively regulates drought stress tolerance in apple. Biochemical analysis showed that MhSHINE2-like directly binds to the GAGA-rich element in the promoter of the ABA biosynthesis gene MhNCED3, promoting its transcription under drought stress. Overexpression of MhNCED3 promotes ABA accumulation and enhances apple drought tolerance by regulating stomatal closure under drought stress. Further studies revealed that MhSHINE2-like physically interacts with 14-3-3 protein, MhGRF3, which also contributes positively to drought tolerance. Notably, MhSHINE2-like and MhGRF3 function cooperatively to modulate the expression of downstream genes, promoting ABA accumulation, and consequently enhancing drought tolerance in apple. These findings reveal a regulatory network mediated by the combined effects of TFs and chaperone proteins, offering valuable genetic resources for the development of drought-tolerant apple cultivars.

Salinization threatens global crop productivity by compromising the growth, development, and ultimate yield of rice (Oryza sativa L.). In this study, we cloned and systematically investigated the function and physiological mechanism of OsABA45 (LOC_Os12g29400), a gene encoding a GRAM domain-containing protein, in mediating rice responses to salt stress. Subcellular localization confirmed OsABA45 as a cytoplasmic protein. Functional characterization of salinity tolerance at the seedling stage revealed that the survival rate of wild-type Nipponbare was 54.37%. By contrast, the OsABA45 knockout lines exhibited a significantly enhanced survival rate of 74.94%, indicating markedly improved salt tolerance. Conversely, the overexpression lines showed a reduced survival rate of 35.78%, reflecting compromised tolerance. Furthermore, the survival rate of wild-type Caidao was 42.90%, whereas the complementation lines reached 80.06%. These results collectively demonstrate that OsABA45 functions as a negative regulator of salt tolerance in rice. Interestingly, during seed germination and post-germination stages, OsABA45 knockout and complementation lines displayed increased sensitivity to abscisic acid (ABA), while overexpression lines exhibited decreased sensitivity. Meanwhile, exogenous ABA application restored salt stress tolerance in the overexpression lines. Further analysis demonstrated that OsABA45 knockout lines significantly upregulated the expression of key ABA biosynthesis genes, promoted endogenous ABA accumulation, and consequently enhanced salt tolerance, evidence OsABA45 mediates salt stress responses by regulating the ABA biosynthesis pathway. Notably, OsABA45 knockout and complemented lines also showed improved tolerance to ionic toxicity, osmotic stress, and oxidative stress, while overexpression lines exhibited reduced tolerance to these stresses. These results indicate that OsABA45 plays vital roles in ABA signal responses and salt tolerance in rice. This study provides novel molecular targets and breeding strategies for improving salt tolerance.

Targeted disruption of a cell wall-modifying gene α-Mannosidase using CRISPR-Cas9 enhances post-harvest shelf life in tomato through ABA accumulation.

S-nitrosoglutathione enhances rice tolerance to salt-submergence by coordinating ethylene, GA, and ABA accumulation and improving ion transport.

Fusarium solani strain K (FsK) and arbuscular mycorrhizal fungi (AMF) are soilborne symbionts that colonize plant roots and modulate stress responses. While most studies focus on individual microbial partners, understanding multipartite microbial interactions under realistic conditions is essential for designing effective inoculants. Here, we investigated the individual and combined effects of FsK, Funneliformis mosseae (F. mosseae) and Rhizophagus irregularis (R. irregularis) on tomato (Solanum lycopersicum) performance under drought and salinity stress in a greenhouse experimental set up. Under stress conditions, each endophyte showed enhanced root colonization. Co-inoculation with multiple microbes diminished this effect, however the functional outcomes were not directly dependent on the extent of microbial establishment. Under drought, FsK consistently promoted shoot growth, water retention and abscisic acid accumulation, while AMF improved nutrient status. Co-inoculation with FsK and F. mosseae led to synergistic improvements in physiological traits, but only under drought conditions. In contrast, salinity responses were less consistent and revealed functional divergence among microbial partners. These findings demonstrate that context-specific microbial combinations can enhance stress resilience in tomato.

Pre-sowing seed treatment (priming) is a strategic tool for programming future crop yield, aimed at improving early plant development and enhancing stress resilience. This study investigated the effects of priming wheat seeds with 100 µM ibuprofen on early ontogeny under optimal conditions and salt stress (100 mM NaCl). An evaluation of germination energy, growth parameters, phytohormone levels (abscisic acid, indolylacetic acid, and cytokinins) and the status of the antioxidant system in 7-day-old seedlings demonstrated that ibuprofen treatment stimulates wheat growth and tolerance, despite its absence of accumulation in plant tissues. Modulation of hormonal balance plays a key role in these protective effects: under optimal conditions, ibuprofen elevates abscisic acid and indolylacetic acid levels, while under salt stress, it prevents excessive abscisic acid accumulation and mitigates the stress-induced decline in indolylacetic acid and cytokinins. Furthermore, ibuprofen promotes a coordinated increase in glutathione, ascorbate, and H2O2 levels, concomitant with the activation of key enzymes (glutathione reductase and ascorbate peroxidase), thereby enhancing the plants’ antioxidant potential. Under saline conditions, ibuprofen pretreatment also reduces stress-induced dysregulation of this system. Therefore, ibuprofen acts as a hormetic preconditioning agent that improves seedling vigor and stress tolerance by fine-tuning hormonal signaling and redox metabolism.

Salinization of arable land is a major adversity factor affecting crop yields. Calcium-dependent protein kinases (CDPKs/CPKs) play crucial regulatory roles in multiple stress responses. However, their functions in alfalfa and the mechanisms of CDPKs in regulating saline-alkali stress are not well elaborated. In this study, we identified MsCDPK29 as a positive regulator of saline-alkali tolerance in alfalfa. Overexpression (OE) of MsCDPK29 in alfalfa displayed tolerance to saline-alkali stress, with higher antioxidant capacity, whereas electrolyte leakage, hydrogen peroxide (H2O2), superoxide anions (O2 -), and malondialdehyde (MDA) contents were lower than wild-type (WT). Conversely, MsCDPK29 RNA interference (RNAi) alfalfa displayed opposite phenotypes. Additionally, MsbZIP14, a basic region-leucine zipper transcription factor, was identified as a MsCDPK29-interacting protein. OE of MsbZIP14 promotes abscisic acid (ABA) accumulation and enhances saline-alkali tolerance. Meanwhile, we showed that MsbZIP14 was phosphorylated by MsCDPK29 at threonine236 (T236) and serine237 (S237) sites, and the phosphorylation is required for the biological function of MsbZIP14 in regulating ABA biosynthesis and saline-alkali stress response. MsbZIP14 directly binds to the promoter of MsNCED3 and activates its expression. Moreover, MsCDPK29 activated MsbZIP14 to enhance the expression of MsNCED3. Collectively, this study uncovered the mechanism whereby MsCDPK29 positively regulates saline-alkali tolerance in alfalfa by phosphorylation of MsbZIP14 to activate MsNCED3 expression.

Phytohormones play essential roles in plant-nematode interactions through complex crosstalk. Although these hormones often accumulate in nematode-resistant plants, the roles of abscisic acid (ABA) and ethylene (ET) in rice (Oryza sativa) resistance to the root-knot nematode (RKN) Meloidogyne graminicola (Mg) remain unclear, particularly regarding concentration dependency and underlying mechanisms. Using exogenous hormone gradient treatments, we show that only high concentrations of ABA (200 µM) and ET-releasing compound ethephon (Eth, 500 µM) induce systemic nematode resistance. High-concentration ET triggers endogenous systemic accumulation of ET and jasmonic acid (JA), accompanied by transient suppression followed by delayed accumulation of ABA, and induces JA-, ABA-, and salicylic acid (SA)-associated transcriptional responses. Exogenous ABA leads to endogenous ABA and SA accumulation and increased expression of related genes, while it suppresses ET biosynthesis gene expression and levels, highlighting a negative feedback effect of ABA on ET. Both hormones converge on a common mitogen-activated protein kinase 5 (OsMPK5)-dependent transcriptional and translational module. Low doses of ABA (50 µM) failed to activate this module and induced plant susceptibility, highlighting a threshold requirement for immune activation. Offspring of rice plants treated bi-weekly with high doses of ABA or ET were less susceptible to nematodes. This intergenerational acquired resistance was also OsMPK5-dependent. Our findings reveal concentration-dependent systemic effects of ABA and ET, whereby high-dose ABA and ET converge on OsMPK5 to reprogram translation and defense gene expression, underpinning both immediate and heritable resistance to root-knot nematodes.

Pectobacterium carotovorum is a gram-negative phytopathogenic bacterium that causes soft rot disease on diverse plant species. It encodes the type III secretion system effector protein, DspE, and its chaperone, DspF. The DspE family proteins form water and solute channels in plant cells, flooding the apoplast to aid bacterial multiplication. In Pseudomonas syringae, the DspE ortholog, AvrE, upregulates abscisic acid (ABA) expression, leading to stomatal closure. In this study, a Pectobacterium carotovorum dspEF mutant did not cause leaf cell death in tobacco leaves. This observation is supported by the lower expression of PCWDE such as pelB, pelI, celV, prtW, and the quorum sensing system transcript expI in tobacco plants prior to visual symptoms (5 hours post-inoculation). Interestingly, neither dspE/F or hrpL mutation affected synthesis of QS signaling molecule AHL under microbiological settings. However, maceration symptoms occurred if leaves infiltrated with the dspEF mutant were kept under high humidity or detached post-infiltration. These leaves showed elevated transcription of ABA synthesis genes compared to infiltrated leaves maintained on the plant under ambient conditions. To validate this involvement, co-infiltration of ABA with the dspEF mutant restored its ability to cause maceration in attached leaves under ambient conditions. Overall, our data suggest that DspE/F facilitates host susceptibility by creating an aqueous apoplast, promoting ABA accumulation and stomata closure.

Abscisic acid confers antibiotic stress tolerance in cucumber by alleviating antibiotic phytotoxicity and decreasing the levels of antibiotic and antibiotic resistance genes.

Micronutrient malnutrition persists as a global health burden, while conventional biofortification approaches suffer from low efficiency and environmental trade-offs. This study aimed to develop and evaluate a foliar-applied selenium–zinc nanocomposite (Nano-ZSe, a mixture of zinc ionic fertilizer and nano selenium) for synergistic Se/Zn co-biofortification in Brassica chinensis L., using a controlled pot experiment that integrated physiological, metabolic, molecular, and rhizosphere analyses. Application of Nano-ZSe at 0.18 mg·kg−1 (Based on soil weight) not only increased shoot biomass by 28.4% but also elevated Se and Zn concentrations in edible tissues by 7.00- and 1.66-fold (within the safe limits established for human consumption), respectively, compared to the control. Mechanistically, Nano-ZSe reprogrammed the ascorbate-glutathione redox system and redirected carbon flux through the tricarboxylic acid cycle, suppressing acetyl-CoA biosynthesis and reducing abscisic acid accumulation. This metabolic rewiring promoted stomatal opening, thereby enhancing foliar nutrient uptake. Simultaneously, Nano-ZSe triggered the coordinated upregulation of BcSultr1;1 (a sulfate/selenium transporter) and BcZIP4 (a Zn2+ transporter), enabling synchronized translocation and the tissue-level co-accumulation of Se and Zn. Beyond plant physiology, Nano-ZSe improved soil physicochemical properties, enriched rhizosphere microbial diversity, and increased crop yield and economic returns. Collectively, this work demonstrates that nano-enabled dual-nutrient delivery systems can bridge nutritional and agronomic objectives through integrated physiological, molecular, and rhizosphere-mediated mechanisms, offering a scalable and environmentally sustainable pathway toward functional food production and the mitigation of hidden hunger.

Waterlogging is a major abiotic stress that restricts plant growth, productivity, and survival by disrupting root aeration and altering hormonal homeostasis. To elucidate the physiological and molecular responses associated with flooding tolerance in Liriodendron hybrids (Liriodendron chinense × Liriodendron tulipifera), this study investigated its morphological, physiological, and transcriptomic changes under 0, 1, 3, and 6 days of waterlogging. Roots exhibited rapid decay, while leaves showed delayed chlorosis and reduced chlorophyll content. Changes in antioxidant enzyme activities reflected enhanced antioxidant capacity, with superoxide dismutase (SOD) activity decreasing and peroxidase (POD) and catalase (CAT) activities increasing. Hormone measurements indicated organ-specific patterns, including abscisic acid (ABA) accumulation in leaves and decreased indole-3-acetic acid (IAA) and gibberellin (GA) levels in both roots and leaves. Transcriptome profiling revealed extensive transcriptional adjustments in hormone biosynthesis, signaling, and stress-responsive pathways, including divergent regulation of ABA-associated genes in leaves and roots and broad downregulation of auxin- and gibberellin-related genes. Key ABA biosynthetic genes (NCED1, ABA2) and signaling components (PYL4, PP2C, ABF) were upregulated in leaves but downregulated in roots, whereas auxin (YUC6) and gibberellin (GA20ox) genes were generally suppressed. These coordinated physiological and molecular responses suggest organ-differentiated adaptation to waterlogging in Liriodendron hybrids, highlighting candidate pathways and genes for further investigation and providing insights for improving flooding tolerance in woody species.

Waseem and colleagues (2025) provide a timely synthesisof why rapid post-drought stomatal reopening isphysiologically important, and they discuss how phytomelatonin, 5-aminolevulinic acid, and brassinosteroids may counter abscisic acid (ABA)-induced closure (Waseemet al. 2025). Their central proposal, that these regulators promote reopening largely by limiting ABA accumulation and attenuating downstream H2O2/Ca2+ signaling in guard cells, is valuable because it shifts attention from drought-phase closure to the recovery bottlenecks that constrain carbon gain after rewatering.

Salinity is among the main abiotic constraints limiting crop productivity worldwide. Salt tolerance can be improved by introducing adaptive traits from wild species and enhancing pre-existing salt-adaptive mechanisms through priming. This study evaluated the beneficial effect of salicylic acid (SA, 1.25 mM) and calcium chloride (CaCl2, 5 mM) seed priming on plant growth under salinity in the domestic barley Hordeum vulgare (Hv) and the wild, salt-adapted Hordeum maritimum (Hm). Primed plants were grown under control, 100 and 200 mM sodium chloride (NaCl) for two weeks. Growth and hormone profiling were performed. Hv showed higher growth inhibition than Hm but was more responsive to stress alleviation by priming, particularly with SA, which increased biomass by up to 47% at 200 mM NaCl. The contrasting responses of both species reflected distinct hormonal strategies. The intrinsic salt tolerance of Hm appears linked to high constitutive levels of stress- and growth-related hormones. In Hv, growth recovery under salinity following priming was associated with hormonal reprogramming, involving reduced abscisic acid (ABA) accumulation and enhanced levels of growth-promoting hormones (indole-3-acetic acid (IAA), trans-zeatin (tZ), and isopentenyl adenine (iP)), especially in roots. Hormonal changes mediated by priming are analyzed in relation to adaptive growth responses and species' ecological origins.

In response to drought stress, land plants close their stomata to minimize transpiration. This action precedes a gradual accumulation of the stress hormone abscisic acid (ABA) that enhances plant drought tolerance. However, the molecular mechanisms that cause the time lag between the onset of stomatal closure and ABA accumulation and coordinate these two phases remain unexplained. Here, we found that Arabidopsis thaliana loss-of-function CLAVATA3/ENDOSPERM SURROUNDING REGION 5 (CLE5) mutants are less tolerant to drought. The CLE5 dodecapeptide (CLE5p) acts as a local signal to induce stomatal closure by binding to the LEUCINE-RICH REPEAT RECEPTOR-LIKE KINASE (LRR-RLK) receptor complex, BARELY ANY MERISTEM 1 (BAM1)–GUARD CELL HYDROGEN PEROXIDE-RESISTANT 1 (GHR1), in guard cells. The BAM1–GHR1–CLE5p module directly phosphorylates two SNF1-related protein kinases, OPEN STOMATA1 (SRK2E) and SRK2D, the central regulators of drought responses in plants, to regulate stomatal movement and drought-responsive gene expression without stimulating ABA biosynthesis or ROS accumulation. Our findings mark a critical step in understanding how plants promptly counteract environmental stresses. The CLEp–LRR-RLK signalling components are highly conserved across plant phyla, suggesting that peptide-mediated rapid stomatal closure is a widespread survival strategy and can be exploited to generate drought-resistant crops.

Abscisic acid (ABA) is a key plant growth regulator widely used in agriculture and ecological restoration. Although metabolic engineering of the fungus Botrytis cinerea can enhance ABA production, it has been hindered by inefficient genetic tools. In this study, we first established a recyclable selection marker system in B. cinerea based on orotidine-5'-phosphate decarboxylase. Subsequently, the CRISPR/Cas9 system was optimized, achieving up to 100% editing efficiency, far surpassing traditional homologous recombination. Based on this platform, multiple metabolic engineering strategies were systematically explored to enhance ABA biosynthesis. Increasing acetyl-CoA supply, inhibiting squalene synthesis, and knocking out key secondary metabolism genes Bcpks12 and Bcphs1 all significantly promoted ABA accumulation. Notably, co-overexpression of Bcacly1 and Bcacly2 combined with 1 g/L citrate increased ABA production to 1.36 g/L, representing a 38.66% improvement. Overall, this study provides an efficient genetic toolkit and a solid foundation for the industrial-scale production of ABA via engineered B. cinerea.