Drought severely limits maize production. Basic helix-loop-helix (bHLH) transcription factors act as key regulators of plant drought responses; however, the precise regulatory networks they coordinate in maize remain largely unclear. Here, we functionally characterized ZmbHLH81, a drought- and abscisic acid (ABA)-responsive bHLH transcription factor in maize. Subcellular localization confirmed that ZmbHLH81 is a nuclear protein. Overexpression of ZmbHLH81 in Arabidopsis enhanced drought tolerance, whereas CRISPR/Cas9-mediated targeted mutagenesis in maize significantly increased plant sensitivity to drought stress. Physiologically, these mutant lines exhibited accelerated water loss, delayed stomatal closure, compromised antioxidant enzyme activities and elevated malondialdehyde (MDA) accumulation under drought stress. DAP-seq analysis demonstrated that ZmbHLH81 specifically recognizes the conserved G-box motif (CACGTG). Furthermore, integrating DAP-seq and transcriptomic data successfully identified the key downstream targets governed by ZmbHLH81. Molecular assays confirmed that ZmbHLH81 directly targets and transactivates the core ABA signaling kinase gene ZmSnRK2.9 and stress-responsive transcription factor genes ZmNAC20 and ZmHDZ4. Taken together, ZmbHLH81 positively regulates maize drought tolerance by directly activating a specific regulatory module that orchestrates ABA-mediated stomatal closure and reactive oxygen species (ROS) scavenging, providing a promising genetic target for breeding climate-resilient crops.

Sulfated peptides, such as PSK, PSY, CIF, and RGF, are crucial regulators of plant growth, development, and stress responses, with their activity dependent on post-translational tyrosine sulfation by tyrosylprotein sulfotransferase (TPST). This study explores the evolutionary history and the interaction mechanisms between TPST and sulfated peptides in plants. Systematic analyses of multi-species genomes show that TPST can be traced back to the chlorophyte lineage, whereas PSK, a sulfated peptide, appears to have emerged in gymnosperms. TPST is evolutionarily conserved, typically present in low copy numbers across plant lineages, while its peptide substrates have expanded in angiosperms. In Liriodendron chinense, TPST-sulfated peptide gene promoters are enriched with cis-regulatory elements linked to abscisic acid, gibberellin responsiveness, and anaerobic induction. Synteny analyses revealed collinearity between sulfated peptide genes in L. chinense, Magnolia biondii, Arabidopsis thaliana, and Populus trichocarpa, but not with Oryza sativa. Molecular docking identified key TPST-PSK interaction sites in the sulfotransferase domain, with several critical residues facilitating binding. Transcriptomic and co-expression network analyses revealed that LcTPST was expressed at lower levels than its peptide precursor genes, while LcPSK2 remained highly expressed after the torpedo stage of somatic embryogenesis. Stress conditions significantly increased PSK-associated module connectivity, enriched in transcription factors such as WRKY, bHLH, bZIP, and MADS. This study provides insights into the evolutionary, structural, and regulatory aspects of the TPST-sulfated peptide system in plants.

Leaf senescence after harvest limits the economic value of leafy cruciferous vegetables such as Chinese flowering cabbage (Brassica rapa ssp. parachinensis). Understanding the intricate gene regulatory networks that govern postharvest leaf senescence offers potential strategies to extend the shelf life of these vegetables. This study elucidated the regulatory networks modulating leaf senescence by utilizing time-series gene expression analysis on postharvest leaves of Chinese flowering cabbage treated with cytokinin analog 6-benzylaminopurine and abscisic acid (ABA). ABA treatment accelerated leaf senescence, including the dismantling of chloroplasts and mitochondria, whereas 6-benzylaminopurine treatment decelerated these processes. Subsequent RNA sequencing and integrated analyses led to the construction of transcriptional regulatory networks comprising 49 transcription factors potentially regulating senescence-related pathways, including reactive oxygen species (ROS) metabolism and chlorophyll degradation. Validation experiments on ROS metabolism confirmed that increased ROS accumulation paralleled the progression of leaf senescence, whereas ABA and 6-benzylaminopurine treatment resulted in opposing effects on ROS scavenging. Furthermore, exogenous ROS treatment promoted leaf senescence and the disassembly of chloroplasts and mitochondria, while ROS inhibitors delayed these processes. Further validation assays affirmed the expression patterns, transcription factor-binding capacities, and activation potentials of eight critical transcription factors and their possible target genes associated with ROS scavenging. Moreover, the role of two transcription factors (BrAGL42 and BrCRF11-2) in regulating postharvest leaf senescence and ROS scavenging ability was verified through transformation assays. Collectively, our findings shed light on the overarching transcription factor-mediated regulatory pathways in postharvest leaf senescence and indicate how cytokinin and ABA modulate this process antagonistically.

The EAR motif-containing adaptor protein ECAP enhances ABI5-mediated ABA signaling to inhibit seed germination in Arabidopsis.

ABSTRACTArbuscular mycorrhizal (AM) fungi can form symbiotic associations with plants and play a significant role in enhancing plant tolerance to acidic stress, wherein arbuscules serve as key structures in this process. However, the response patterns of arbuscule development and function under low pH conditions remain poorly understood. Previous studies have shown that abscisic acid (ABA) can regulate arbuscule development, but whether ABA regulates arbuscule development and function under low pH conditions is unknown. In this study, the model plant tomato (Solanum lycopersicum) was used as the host plant, inoculated with AM fungi to investigate the regulatory effects of low pH and exogenous ABA on arbuscule development and function. The results showed that (1) as time progressed, the mycorrhizal colonization increased, and arbuscules gradually developed from the main trunk to mature and senescent stages; however, low pH values inhibited arbuscule development. (2) High concentrations of ABA inhibited root growth and mycorrhizal colonization, whereas low concentrations promoted mycorrhizal colonization, with 10−7 M identified as the optimal concentration for maximizing mycorrhizal colonization. (3) Both low pH and ABA‐deficient mutants significantly inhibited mycorrhizal colonization, alkaline phosphatase activity, and the expression of genes related to arbuscular development. However, exogenous ABA did not significantly affect the expression of genes associated with arbuscular function. Low concentrations of ABA could restore the inhibition of arbuscule development and function caused by low pH and ABA‐deficient mutants. Additionally, low pH significantly inhibited the ABA content in mycorrhizae, while exogenous ABA treatment significantly increased the ABA content in mycorrhizae. Our research results indicate that low dosage of ABA enhances arbuscule formation and function, and recovers the inhibitory effect of low pH on this process. Low pH may regulate arbuscule development and function by modulating ABA in roots, and ABA may regulate mycorrhizal development by affecting lipid synthesis and transport.

PSRP2 interacts with F-box protein FOF2 to regulate ABA and drought response in Arabidopsis.

Abscisic acid-responsive element binding factor 1 (OoAREB1) transcription factor mediates drought stress response in Oxytropis ochrocephala via interaction with sucrose nonfermenting 1-related protein kinase 2.1 (OoSnRK2.1) and OoSnRK2.6.

The composition and ratio of sugars and organic acids are crucial for strawberry ( Fragaria × ananassa Duch) taste and flavor. Strawberry at five development and ripening stages-small green (SG), big green (BG), white (W), pink (P) and red stage (R) were analyzed for phytohormones, sugars, organic acids, related genes and transcription factors (TFs) expressions dynamics. The signals of auxin (IAA), salicylic acid (SA), brassinolide (BR), 24-epibrassinolide (EBL), gibberellin (GA) 3, GA 5 , GA 14 and GA 19 increased at the development stage, while the relative abundance of abscisic acid (ABA), melatonin (MT) and GA 51 was higher at the ripening stage. Sucrose and glucose were the primary sugars, and malic acid exhibited the highest content. The expression levels of FaSPS , FaSS , FaMDH, FaTCP7 , FaNAC73 , FaARF2 and FaCMB1 decreased, while the FaCS expression level increased during ripening. Correlation network analysis revealed trends of association between sugars/organic acids accumulation and specific phytohormones and gene expression level. This study significantly deepens the understanding of strawberry quality formation mechanisms and provides critical theoretical targets for molecular breeding. • The contents of SA, BR, EBL, GA 5 and GA 19 accumulated from the SG to BG stage. • The contents of ABA and MT were relatively high from the W to the R stage. • Sucrose was positively correlated with ABA but negatively correlated with FaARF2 . • ABA positively while GA₃ negatively correlated with malic acid accumulation. • AsA was positively correlated with SA, EBL, GA 14 , FaTCP7 , FaNAC73 , FaARF2 and FaCMB1 .

Seed dormancy is crucial for plant reproduction, ensuring that germination occurs under favorable environmental conditions. In rice, moderate seed dormancy reduces the risk of pre-harvest sprouting, thereby minimizing yield losses and preserving seed quality. In this study, we cloned the seed dormancy gene ObRc from African wild rice (Oryza barthii) accession W1411. ObRc encodes a basic helix-loop-helix transcription factor. In African cultivated rice (Oryza glaberrima), a 2-bp insertion in the ObRc coding region introduces a premature stop codon, resulting in a loss-of-function allele. We demonstrate that ObRc regulates seed dormancy by modulating zeaxanthin biosynthesis (an abscisic acid [ABA] precursor), thereby influencing endogenous ABA levels. Additionally, ObRc influences seed coat pigmentation by regulating the expression of multiple genes in anthocyanidin biosynthesis, ultimately impacting both seed coat color and permeability. The functional ObRc allele is preserved in the vast majority of African cultivated rice accessions, likely because it confers moderate dormancy, which enhances environmental adaptation in West African climates and contributes to the preservation of seed nutritional value. Elucidating the molecular mechanism of ObRc provides valuable insights for improving PHS resistance and enhancing the nutritional value of rice through breeding.

OsFT coordinates photosynthetic stability and carotenoid metabolism to regulate tillering in rice.

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

Functional characterization of the PP2C family reveals NtPP2C171 as a negative regulator of drought tolerance in tobacco

Osmotic stress resulting from drought or high salinity, is a major environmental constraint that severely restricts the growth and development of apple (Malus × domestica) trees, as well as the yield and quality of the fruit. M. sieversii, the wild ancestor of modern cultivated apples, is highly valued in breeding programs due to its remarkable tolerance to abiotic stresses than M. domestica. While microRNAs (miRNAs) and their targets play crucial roles in plant adaptation to abiotic stress, their specific functions in apple remain largely unexplored. This study elucidates the regulatory mechanism by which miR477b-MsDELLA-like-MsNF-YC9 modulate abscisic acid (ABA) biosynthesis in apple, thereby enhancing osmotic stress tolerance. We identified a vascular-localized miR477b along with its target, MsDELLA-like, and the gene NINE-CIS-EPOXYCAROTENOID DIOXYGENASE 3.2 (MsNCED3.2), to investigate ABA biosynthesis regulation. Both knockout of miR477b and overexpression of MsDELLA-like resulted in elevated endogenous ABA and improved tolerance to salt and mannitol stress in the transgenic lines. Mechanistically, we found that MsDELLA-like physically interacts with transcription factor NUCLEAR FACTOR Y, Subunit C9 (MsNF-YC9), enhancing its binding affinity to the MsNCED3.2 promoter. This interaction activates MsNCED3.2 transcription, consequently promoting ABA biosynthesis. These findings reveal that the wild apple rootstock M. sieversii enhances osmotic stress resistance by integrating small RNA pathways with ABA biosynthesis regulation.

The transcription factor SmWRKY20 positively regulates abscisic acid-induced salvianolic acids biosynthesis by activating SmC4H1 in Salvia miltiorrhiza.

The C₂H₂-type zinc finger transcription factor PpZAT10 mediates abscisic acid-induced carotenoid accumulation in yellow peach.

Phytochrome-interacting factors (PIFs): Integrating phytohormone signals at the nexus of development and stress adaptation.

TaZAT11-B interacts with corepressor TaTPL-A to regulate dark-induced leaf senescence by modulating H2O2​ homeostasis in wheat.

Lectin receptor-like kinases (LecRLKs) are plant-specific kinases that play critical roles in stress signaling. G-type LecRLKs, which possess an α-mannose-binding bulb lectin domain, are implicated in diverse stress responses; however, their roles in drought responses in pepper plants remain poorly understood. Therefore, this study aims to identify and functionally characterize a pepper G-type LecRLK, CaRLK1. CaRLK1 expression was significantly induced by multiple abiotic stresses, particularly dehydration. Additionally, functional analysis using virus-induced gene silencing revealed that CaRLK1-silenced pepper plants showed reduced drought tolerance and increased leaf water loss, associated with impaired stomatal closure and attenuated leaf temperature increases following abscisic acid (ABA) treatment. Moreover, CaRLK1 silencing reduced the expression of several drought-responsive genes, including CaOSR1, CaDREBLP1, and CaLOX1, under dehydration conditions. Collectively, these findings suggest that CaRLK1 functions as a positive regulator of drought stress responses in pepper plants by modulating ABA-dependent stomatal aperture dynamics and drought-responsive gene expression.

Transcriptomic and phenotypic analysis of maize with CRISPR/Cas9-mediated targeted mutagenesis of melatonin synthesis genes under drought stress.

Salt, drought and freezing stress were major abiotic factors limiting plant growth, development and yield. Halostachys caspica (Amaranthaceae), a halophyte native to saline-arid desert regions, tolerated multiple abiotic stresses, but its molecular mechanisms of stress tolerance remain unclear. By integrating the small RNA library and transcriptome data of H. caspica under high salinity, HcmiR172e was identified as a differentially expressed miRNA and selected for the study of multiple abiotic stress responses. Using its mature sequence (20 nt) to align with upregulated genes from the transcriptome, HcTOE3 (AP2 subfamily transcription factor belonging to the AP2/ERF family) was preliminarily predicted as its target gene through bioinformatic analysis. Our previous work demonstrated that HcTOE3 was strongly upregulated by multiple abiotic stresses, including salinity, drought, heat and low temperature. Furthermore, overexpression of HcTOE3 conferred freezing tolerance to Arabidopsis throughout the entire growth period. In this study, miRNA expression analyses showed that HcmiR172e was significantly downregulated in the assimilating branches of H. caspica under low temperature, heat, salt, drought, oxidative stress and abscisic acid (ABA) application. Tobacco transient expression assays and 5'RLM-RACE confirmed that HcmiR172e directly cleaved HcTOE3 transcripts in the region close to the 5'end of the ORF. HcmiR172e-overexpressing Arabidopsis displayed increased sensitivity to salt, drought, freezing stresses and ABA treatment, along with enhanced growth inhibition, elevated reactive oxygen species (ROS) accumulation, decreased osmolyte content and downregulation of stress-responsive genes. In contrast, HcTOE3-overexpressing Arabidopsis exhibited the opposite phenotypes, physiological responses and corresponding gene expression patterns under multiple stress treatments. These findings collectively elucidated the antagonistic regulatory roles of HcmiR172e and HcTOE3 in plant abiotic stress responses, providing novel molecular targets for engineering stress-tolerant crops for saline, arid, freezing environments.