Abscisic Acid Response Research Articles

The physiological and molecular responses of potato tuberization to projected future elevated temperatures.

Potato (Solanum tuberosum L.) is one of the most important food crops globally and is especially vulnerable to heat stress. However, substantial knowledge gaps remain in our understanding of the developmental mechanisms associated with tuber responses to heat stress. This study used whole-plant physiology, transcriptomics, and phytohormone profiling to elucidate how heat stress affects potato tuber development. When plants were grown in projected future elevated temperature conditions, abscisic acid (ABA) levels decreased in leaf and tuber tissues, whereas rates of leaf carbon assimilation and stomatal conductance were not significantly affected compared to those plants grown in historical temperature conditions. While plants grown in projected future elevated temperature conditions initiated more tubers per plant on average, there was a 66% decrease in mature tubers at final harvest compared to those plants grown in historical temperature conditions. We hypothesize that reduced tuber yields at elevated temperatures are not due to reduced tuber initiation, but due to impaired tuber filling. Transcriptomic analysis detected significant changes in the expression of genes related to ABA response, heat stress and starch biosynthesis. The tuberization repressor genes SELF PRUNING 5G (StSP5G) and CONSTANS-LIKE1 (StCOL1) were differentially expressed in tubers grown in elevated temperatures. Two additional known tuberization genes, IDENTITY OF TUBER 1 (StIT1) and TIMING OF CAB EXPRESSION 1 (StTOC1), displayed distinct expression patterns under elevated temperatures compared to historical temperature conditions but were not differentially expressed. This work highlights potential gene targets and key developmental stages associated with tuberization to develop potatoes with greater heat tolerance.

Comparative genomics analysis of the MYB gene family in barley: preliminary insights into evolution and biological function in Blue Qingke.

The Myeloblastosis related (MYB) family is one of the most widely distributed transcription factor families in plants and plays a significant role in plant growth and development, hormone signal transduction, and stress response. There are many reports on MYB family species, but the research on Qingke is still limited. This study used comparative genomics methods to analyze gene and protein structure, protein physicochemical properties, chromosome localization, and evolution. A bioinformatics approach was used to systematically analyze the HvMYB gene family. At the milk stage, soft dough stage, and mature stage, White and Blue Qingke grains were selected for RNA sequencing (RNA-seq), among which two proteins interacted (HvMYB and HvMYC). The expression of this gene family was analyzed through RNA-seq, and the expression levels of HvMYB and HvMYC in the grains of two different color varieties were analyzed by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Finally, the interaction between HvMYB and HvMYC was verified by bimolecular fluorescence complementation (BiFC) experiments. A total of 92 Qingke HvMYB genes were identified and analyzed, and 92 HvMYB proteins were classified into five categories. Cis-acting elements associated with abscisic acid response, light response, and methyl jasmonate (MeJA) response were found in the promoter regions of most MYB genes. Using qRT-PCR combined with RNA-seq analysis showed that MYB gene was highly expressed in the soft dough stage and was varietal specific. Subcellular localization indicated that HvMYB was located in the nucleus and cell membrane, HvMYC was located in the nucleus, cell membrane, and cytoplasm. Through BiFC analysis, it has been proven that HvMYB in the MYB family and HvMYC in the basic helix-loop-helix (bHLH) family can interact. This study provides a preliminary theoretical basis for understanding the function and role of the Qingke MYB gene family and provides a reference for the molecular mechanism of Qingke gene evolution.

Genome-wide identification of HIPP and mechanism of SlHIPP4/7/9/21/26/32 mediated phytohormones response to Cd, osmotic, and salt stresses in tomato

Heavy-metal-associated isoprenylated plant proteins (HIPPs) contributed to abiotic tolerance in vascular plants. Up to now, the HIPP gene family of tomato (Solanum lycopersicum L.) had not been thoroughly understood. In the present study, 34 SlHIPP genes were identified from the tomato genome using the Hidden Markov Model (HMM). The phylogenetic analysis revealed that the evolution of SlHIPPs was highly conserved. The cis-acting element analysis indicated that SlHIPP genes might be involved in phytohormones and abiotic stresses. We constructed venn diagram with 17 genes containing stress-related motifs as well as 15 genes and 19 genes expressing in leaves and roots in RNA-seq data, suggesting that SlHIPP4/7/9/21/26/32 were selected as candidate genes for study. The quantitative real-time PCR (qRT-PCR) analysis showed that 6 candidate genes were indicated to be involved in osmotic and salt stress tolerance and SlHIPP7/21/26/32 responded to cadmium (Cd) tolerance. The virus-induced silencing of 6 candidate genes caused growth inhibition in stress conditions, further illustrating that 6 candidate genes played a positive role in abiotic conditions. Importantly, the phytohormone analysis implied that 6 candidate genes mediated abscisic acid (ABA), salicylic acid (SA), gibberellin (GA3), auxin (IAA), or methyl jasmonate (MeJA) responses to Cd, osmotic, or salt stress tolerance. These findings indicated that SlHIPP4/7/9/21/26/32 were key regulators of abiotic stress responses in tomato seedlings, functioning through multiple phytohormone pathways.

Functional Diversity of A-Type RING Ligases (ATL) Genes: Insights into the Crucial Roles of E3 Ubiquitin Ligases in Plant Biology

AbstractE3 ubiquitin ligases are vital components of the ubiquitin–proteasome system (UPS), responsible for maintaining protein balance and controlling cellular functions. E3 ligases target specific proteins for degradation or modify their activities through ubiquitin attachment. One prominent E3 ligase family is the ATL family, which comprises 100 members in Arabidopsis thaliana and has significantly expanded in plant genomes. All ATLs share a common domain architecture, featuring a transmembrane domain at the amino-terminal region, a distinct RING-H2 finger domain, and the GLD motif. The RING domain facilitates interactions between E3 ligases, E2-conjugating enzymes, and target proteins, enabling the transfer of ubiquitin molecules. The amino-terminal and carboxy-terminal regions introduce sequence diversity and potentially mediate interactions with other components that assist in UPS function or target recognition. ATLs had been classified within groups, each group encompasses specific ATLs with defined roles in various biological processes. For example, group C-ATLs are implicated in drought tolerance, flower development, phosphate homeostasis, and immune signaling. G-ATLs are associated with carbon/nitrogen stress, immune signaling, salt stress, ABA responses, cadmium tolerance, and sugar-mediated plant growth. A-ATLs participate in early elicitor-response, salt and drought responses, and flowering time regulation. Lastly, D-ATLs are involved in the regulation of programmed cell death. This review let perceive ATLs as a cohesive group of E3 ligases, shedding light on their functional diversifity and redundancy, specifically examining their participation in diverse biological processes, explore their evolutionary history shaped by gene duplication events, and appraise their interactions with key proteins and targets of ubiquitination. This comprehensive overview aims to offer insights into the role of ATLs in plant adaptation, defense mechanisms, and stress tolerance, while also underlying molecular and evolutionary mechanisms and regulatory networks that govern these processes.

Identification and analysis of drought-responsive F-box genes in upland rice and involvement of OsFBX148 in ABA response and ROS accumulation

BackgroundUpland rice varieties exhibit significant genetic diversity and broad environmental adaptability, making them ideal candidates for identifying consistently expressed stress-responsive genes. F-box proteins typically function as part of the SKP1-CUL1-F-box protein (SCF) ubiquitin ligase complexes to precisely regulate gene expression and protein level, playing essential roles in the modulation of abiotic stress responses. Therefore, utilizing upland rice varieties for screening stress-responsive F-box genes is a highly advantageous approach.ResultsThrough mRNA-seq analysis in the Brazilian upland rice (cv. IAPAR9), the research identified 29 drought-responsive F-box genes. Gene distribution and duplication analysis revealed these genes are distributed on 11 of the 12 chromosomes and 10 collinear gene pairs were identified on different chromosomes. 13 cis-elements or binding sites were identified in the promoters of the 29 drought-responsive F-box genes by analysis. Protein domain, stability and subcellular localization analysis results suggest that these F-box proteins possess F-box domain and several other domains, and they are mostly unstable proteins with subcellular localization in cytoplasm, nucleus, chloroplasts, mitochondria and endoplasmic reticulum. Most of drought-responsive F-box genes exhibited expression in various tissues such as root, stem, leaf, leaf sheath and panicle except for OsFBO10 and OsFBX283. These genes exhibited various responses to abiotic stresses such as osmotic, cold, heat, and salt stresses, along with ABA treatment. Importantly, a frame-shift mutation in OsFBX148 was created in the ZH11 variety, leading to altered ABA signal transduction and ROS accumulation. The study further elucidated the interaction of OsFBX148 with SKP1 family proteins OSK4/7/17 to form the SCF complex, dependent on the F-box domain.ConclusionsThe research identified and analyzed 29 drought-responsive F-box genes in upland rice and provides valuable insights into the role of OsFBX148 in ABA and ROS responses. It establishes a basis for future exploration of F-box genes in improving resistance to abiotic stresses, especially drought.

The RALF1-FERONIA complex phosphorylates FREE1 to attenuate abscisic acid signaling during seedling establishment.

The receptor-like kinase FERONIA (FER), together with its ligand rapid alkalinization factor 1 (RALF1) peptide, plays a crucial role in regulating stress responses, including its involvement in modulating abscisic acid (ABA) signaling. FER has been shown to activate ABA Insensitive 2 (ABI2) in the cytoplasm, leading to the suppression of ABA signaling. However, its regulation of nucleus events in the ABA response remains unclear. FREE1, identified as a plant-specific component of the endosomal sorting complex required for transport (ESCRT) in eukaryotes, serves as an important negative regulator in ABA signaling. In this study, we elucidate that upon RALF1 treatment, FER phosphorylates FREE1, promoting the accumulation of FREE1 protein in the nucleus in Arabidopsis (Arabidopsis thaliana). Consequently, FREE1 suppresses ABA sensitivity by inhibiting the expression of ABA-response genes. Mutating the six identified phosphorylation sites on FREE1, mediated by FER, to non-phosphorylable residues results in reduced nucleus localization of FREE1 and increased hypersensitivity to ABA. Our data also show that these six phosphorylation sites are likely involved in regulating plant survival under salt stress. Collectively, our study not only unveils an additional function of FER in attenuating ABA signaling in the nucleus but also provides a possible insight into the role of the RALF1-FER-FREE1 module in coordinating plant growth and salt stress tolerance.

CsWRKY29, a key transcription factor in tea plant for freezing tolerance, ABA sensitivity, and sugar metabolism

Tea plants (Camellia sinensis L.) are prone to spring frosts, leading to substantial economic damage. WRKY transcription factors are key in plant abiotic stress responses, yet the role of CsWRKY29 in freezing tolerance is unclear. In this study, quantitative real-time PCR (qRT-PCR) and transient green fluorescent protein assay revealed that CsWRKY29 localizes to the nucleus and its expression is induced by cold and abscisic acid (ABA). CsWRKY29 overexpression in Arabidopsis enhanced freezing tolerance, reduced electrolyte leakage, increased soluble sugars, and boosted superoxide dismutase activity, with upregulated COR genes. These lines also showed heightened ABA and glucose sensitivity. Cold treatment of CsWRKY29-overexpressing lines upregulated AtABI5, AtHXK1, and AtSUS4 compared to wild type, and yeast one-hybrid assays confirmed CsWRKY29 binding to the W-box in the CsABI5 promoter. Furthermore, the application of virus-induced gene silencing (VIGS) technology to reduce CsWRKY29 expression in tea plants revealed a significant decrease in the transcript levels of CsCBFs, CsABI5, CsHXK1, and CsSUS4 in the silenced plants. In summary, our findings indicate that CsWRKY29 may serve as a critical transcription factor that contributes to freezing tolerance, ABA responsiveness, and sugar metabolism within tea plants.

Altering endogenous cytokinin content by GmCKX13 as a strategy to develop drought-tolerant plants

Climate-resilient crops are essential to meet the growing food demands of an ever-increasing world population. The phytohormone cytokinins (CKs) have been well established to regulate plant adaptation to drought. Previously, we reported that GmCKX13, encoding a CK oxidase/dehydrogenase in soybean (Glycince max), was differentially expressed under drought. Here, we further characterized its in planta function to assess if GmCKX13 could be a candidate gene to develop drought-tolerant crops. Transgenic Arabidopsis 35S:GmCKX13 plants ectopically and constitutively expressing GmCKX13 using the 35S promoter had an increase in root length, while showing a reduction in shoot height and biomass. CK contents were reduced in 35S:GmCKX13 plants, coupled with the reduced expression of all AtCKX genes and increased expression of all Arabidopsis isopentenyl transferase (AtIPT) genes, except AtIPT2 and AtIPT9 that are responsible for the production of cis-zeatin-type CKs. The 35S:GmCKX13 plants showed improved tolerance to drought and more sensitivity to the treatment with exogenous abscisic acid (ABA). Under the control of the drought-responsive promoter RD29A, the transgenic RD29A:GmCKX13 Arabidopsis plants had a similar phenotype as that of the wild-type (WT) plants under normal conditions. Under dehydration, we found a significant increase in the expression of the transgene coupled with a higher leaf relative water content in RD29A:GmCKX13 plants when compared with WT plants. In consistence with this finding, the RD29A:GmCKX13 plants exhibited higher survival rates and 30 % higher seed yield than the WT plants under drought conditions. Taken together, our results demonstrated that GmCKX13 is an excellent gene for developing drought-tolerant crops by altering endogenous CK levels and ABA responsiveness when being driven by a drought-responsive promoter.

The Arabidopsis E3 ubiquitin ligase DOA10A promotes localization of abscisic acid (ABA) receptors to the membrane through mono-ubiquitination in ABA signaling.

The endoplasmic reticulum-associated degradation (ERAD) system eliminates misfolded and short-lived proteins to maintain physiological homeostasis in the cell. We have previously reported that ERAD is involved in salt tolerance in Arabidopsis. Given the central role of the phytohormone abscisic acid (ABA) in plant stress responses, we sought to identify potential intersections between the ABA and the ERAD pathways in plant stress response. By screening for the ABA response of a wide array of ERAD mutants, we isolated a gain-of-function mutant, doa10a-1, which conferred ABA hypersensitivity to seedlings. Genetic and biochemical assays showed that DOA10A is a functional E3 ubiquitin ligase which, by acting in concert with specific E2 enzymes, mediates mono-ubiquitination of the ABA receptor, followed by their relocalization to the plasma membrane. This in turn leads to enhanced ABA perception. In summary, we report here the identification of a novel RING-type E3 ligase, DOA10A, which regulates ABA perception by affecting the localization and the activity of ABA receptors through their mono-ubiquitination.

Wheat TaPYL9-involved signalling pathway impacts plant drought response through regulating distinct osmotic stress-associated physiological indices.

The abscisic acid (ABA) signalling pathway plays a crucial role in plants' response to drought stress. In this study, we aimed to characterize the impact of an ABA signalling module, which consisted of TaPYL9 and its downstream partners in Triticum aestivum, on plant drought adaptation. Our results showed that TaPYL9 protein contains conserved motifs and targets plasma membrane and nucleus after being sorted by the endoplasmic reticulum. In addition, TaPYL9 transcripts in both roots and leaves were significantly upregulated in response to drought stress. We conducted glucuronidase (GUS) histochemical staining analysis for transgenic plants carrying a truncated TaPYL9 promoter, which suggested that cis-elements associate with ABA and drought response, such as ABRE, DRE and recognition sites MYB and MYC, regulating the gene transcription under drought conditions. Using protein interaction assays (i.e., yeast two-hybrid, bimolecular fluorescence complementation (BiFC), co-immunoprecipitation (Co-IP) and in vitro pull-down), we demonstrated interactions between the intermediate segment of TaPYL9, the intermediate segment of TaPP2C6, the N-terminus of TaSnRK2.8 and the C-terminus of the transcription factor TabZIP1 in wheat, indicating the involvement of TaPYL9 in the constitution of an ABA signalling module, namely TaPYL9/TaPP2C6/TaSnRK2.8/TabZIP1. Transgene analysis revealed that TaPYL9, TaSnRK2.8 and TabZIP1 positively regulated drought response, while TaPP2C6 negatively regulated it, and that these genes were closely associated with the regulation of stomata movement, osmolyte accumulation and ROS homeostasis. Electrophoretic mobility shift (EMSA) and transcriptioal activation assays indicated that TabZIP1 interacted promoters of TaP5CS2, TaSLAC1-1 and TaCAT2 and activated transcription of these genes, which regulated proline biosynthesis, stomata movement and ROS scavenging upon drought signalling, respectively. Furthermore, we found that the transcripts of TaPYL9 and stress-responsive genes were positively correlated with yields in wheat cultivars under field drought conditions. Altogether, our findings suggest that the TaPYL9-involved signalling pathway significantly regulates drought response by modulating osmotic stress-associated physiological processes in T. aestivum.

Genome-wide analysis of the Amorphophallus konjac AkCSLA gene family and its functional characterization in drought tolerance of transgenic arabidopsis

BackgroundAmorphophallus konjac (A. konjac), a perennial tuberous plant, is widely cultivated for its high konjac glucomannan (KGM) content, a heteropolysaccharide with diverse applications. The cellulose synthase-like (CSL) gene family is known to be a group of processive glycan synthases involved in the synthesis of cell-wall polysaccharides and plays an important role in the biological process of KGM. However, in A. konjac the classification, structure, and function of the AkCSLA superfamily have been studied very little.ResultsBioinformatics methods were used to identify the 11 AkCSLA genes from the whole genome of Amorphophallus konjac and to systematically analyze their characteristics, phylogenetic evolution, promoter cis-elements, expression patterns, and subcellular locations. Phylogenetic analysis revealed that the AkCSLA gene family can be divided into three subfamilies (Groups I- III), which have close relationships with Arabidopsis. The promoters of most AkCSLA family members contain MBS elements and ABA response elements. Analysis of expression patterns in different tissues showed that most AkCSLAs are highly expressed in the corms. Notably, PEG6000 induced down-regulation of the expression of most AkCSLAs, including AkCSLA11. Subcellular localization results showed that AkCSLA11 was localized to the plasma membrane, Golgi apparatus and endoplasmic reticulum. Transgenic Arabidopsis experiments demonstrated that overexpression of AkCSLA11 reduced the plant’s drought tolerance. This overexpression also inhibited the expression of drought response genes and altered the sugar components of the cell wall. These findings provide new insights into the response mechanisms of A. konjac to drought stress and may offer potential genetic resources for improving crop drought resistance.ConclusionIn conclusion, the study reveals that the AkCSLA11 gene from A. konjac negatively impacts drought tolerance when overexpressed in Arabidopsis. This discovery provides valuable insights into the mechanisms of plant response to drought stress and may guide future research on crop improvement for enhanced resilience.

The transcription factor TaFDL2-1A functions in auxin metabolism mediated by abscisic acid to regulate shoot growth in wheat.

Genetic strategies can be effective in improving wheat (Triticum aestivum L.) drought stress tolerance, but accumulating evidence suggests that overexpressing drought-resistance genes, especially genes related to the abscisic acid (ABA) signaling pathway, can retard plant growth. We previously characterized the positive roles of the wheat bZIP transcription factor TaFD-Like2-1A (TaFDL2-1A) in drought stress tolerance and ABA biosynthesis and response, whereas a dwarfing shoot exhibited under normal conditions. This study determined the underlying mechanisms that allow TaFDL2-1A to affect shoot growth. Overexpressing TaFDL2-1A decreased cell length, cell width, leaf size, shoot length, and biomass in wheat. The results of RNA-seq showed that multiple differently expressed transcripts are enriched in the auxin signaling pathway. Further analysis indicated higher expression levels of Gretchen Hagen3 (GH3) genes and lower indole-3-acetic acid (IAA) concentrations in the TaFDL2-1A overexpression lines. Exogenous IAA treatment restored the phenotypes of the TaFDL2-1A overexpression lines to wild-type levels. Transcriptional regulation analysis suggested that TaFDL2-1A enhances the expression of auxin metabolism genes, such as TaGH3.2-3A, TaGH3.2-3B, TaGH3.8-2A, and TaGH3.8-2D, by directly binding to ACGT core cis-elements. Furthermore, tafdl2 knock-out plants had lower expression levels of these GH3 genes and higher IAA levels than Fielder wheat. These GH3 gene expression and IAA levels were induced and reduced in Fielder wheat and tafdl2 knock-out plants treated with exogenous ABA. Our findings elucidate mechanisms underlying the functional redundancy of TaFDL2-1A in the crosstalk between ABA and IAA to affect shoot growth and provide insights into the balance between drought resistance and yield in wheat.

OsPP2C49, a Negative Regulatory Factor in the Abscisic Acid Signaling Pathway, Positively Regulates Grain Yield in Rice

Clade A type 2C protein phosphatases (PP2Cs) are crucial components of the abscisic acid (ABA) signaling pathway. Research on clade A PP2Cs has focused more on their roles related to ABA signaling and stress responses than on the molecular mechanisms mediating their effects on plant growth and grain yield. Rice (Oryza sativa L.) is an important food crop worldwide. We previously determined that OsPP2C49, which encodes a rice clade A PP2C family member, negatively controls rice responses to drought, salt, and high-temperature stresses. In this study, we investigated the regulatory effects of OsPP2C49 on ABA responses and rice grain yield. By analyzing potential interactions with core ABA components, including pyrabactin resistance 1 (PYR1)/PYR1-like (PYL)/regulatory component of the ABA receptor (RCAR) and stress-activated protein kinases (SAPKs), we confirmed that OsPP2C49 is involved in the ABA signaling pathway. OsPP2C49 overexpression led to decreased ABA sensitivity and increased rice grain yield; the opposite phenotypes were observed in the ospp2c49 knockout mutants. Therefore, OsPP2C49 negatively regulates ABA responses, but positively modulates rice grain yield. Furthermore, we found that OsPP2C49 can interact with and dephosphorylate five OsSAPKs in vitro. Unlike OsPP2C49, these OsSAPKs positively modulate ABA responsiveness, but negatively affect rice yield. These findings indicate that OsPP2C49 may partially regulate ABA responses and rice grain production by dephosphorylating OsSAPKs. This study preliminarily explored the molecular basis of the regulatory effects of OsPP2C49 on rice plant growth and grain yield.

Development and drought escape response in Arabidopsis thaliana are regulated by AtPLC1 in response to abscisic acid.

AtPLC1 plays a critical role in plant growth, development, and response to drought stress. Phosphoinositide-specific phospholipase C (PI-PLC) hydrolyzes substrates to generate secondary messengers crucial for plant growth, development, and stress responses. Drought escape (DE) response is an adaptive strategy that plants employ under drought conditions. The expression levels of the flower meristem-specific gene APETALA 1 and flowering regulatory genes FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 were downregulated in plc1, and FLOWERING LOCUS C was upregulated. The flowering time of the plc1flc double mutant was earlier than that of the wild type. Transcriptome analysis revealed that the Gene Ontology of differentially expressed genes (DEGs) was enriched in abscisic acid (ABA) response signaling, and Kyoto Encyclopedia of Genes and Genomes analysis revealed differential gene expression annotated to plant hormone signaling pathways. Our experiments show that AtPLC1 is upregulated by ABA in Arabidopsis. Under ABA induction and water stress, wild-type plants exhibit a DE response, and the DE response in plc1 disappears. Expression levels of ABA signaling pathway transcription factors ABA-responsive element-binding factors 3 (ABF3) and ABF4 were downregulated in plc1. In conclusion, our study suggests that AtPLC1 participates in regulating plant growth and development and participates in the DE response through the regulation of ABA signaling pathway transcription factors ABF3/ABF4. The study enhances our comprehension of the role of AtPLC1 in plant development and drought stress, providing a theoretical foundation for further investigation into DE responses.

Genome-Wide Analysis of the Phospholipase Ds in Perennial Ryegrass Highlights LpABFs-LpPLDδ3 Cascade Modulated Osmotic and Heat Stress Responses.

The phospholipase Ds (PLDs) are crucial for cellular signalling and play roles in plant abiotic stress response. In this study, we identified 12 PLD genes from the genome data of perennial ryegrass (Lolium perenne), which is widely used as forage and turfgrass. Among them, LpPLDδ3 was significantly repressed by ABA treatment, and induced by drought stress and heat stress treatments. The ectopic overexpression (OE) of LpPLDδ3 in Arabidopsis enhanced plant tolerance to osmotic and heat stress as demonstrated by an increased survival rate and reduced malondialdehyde (MDA) accumulation and electrolyte leakage (EL). Arabidopsis endogenous ABA RESPONSIVE ELEMENT BINDING FACTORs (ABFs) and heat stress responsive genes were elevated in LpPLDδ3 OE lines under osmotic and heat stress treatments. Additionally, overexpression of LpPLDδ3 in perennial ryegrass protoplasts could increase heat stress tolerance and elevate expression level of heat stress responsive genes. Moreover, LpABF2 and LpABF4 depressed the LpPLDδ3 expression by directly binding to its ABRE core-binding motif of promoter region. In summary, LpPLDδ3 was repressed by LpABF2 and LpABF4 and positively involved in perennial ryegrass osmotic and heat stress responses.

Transcriptomic dynamics of ABA response in Brassica napus guard cells

Drought has a significant, negative impact on crop production; and these effects are poised to increase with climate change. Plants acclimate to drought and water stress through diverse physiological responses, primarily mediated by the hormone abscisic acid (ABA). Because plants lose the majority of their water through stomatal pores on aerial surfaces of plants, stomatal closure is one of the rapid responses mediated by ABA to reduce transpirational water loss. The dynamic changes in the transcriptome of stomatal guard cells in response to ABA have been investigated in the model plant Arabidopsis thaliana. However, guard cell transcriptomes have not been analyzed in agronomically valuable crops such as a major oilseed crop, rapeseed. In this study, we investigated the dynamics of ABA-regulated transcriptomes in stomatal guard cells of Brassica napus and conducted comparison analysis with the transcriptomes of A. thaliana. We discovered changes in gene expression indicating alterations in a host of physiological processes, including stomatal movement, metabolic reprogramming, and light responses. Our results suggest the existence of both immediate and delayed responses to ABA in Brassica guard cells. Furthermore, the transcription factors and regulatory networks mediating these responses are compared to those identified in Arabidopsis. Our results imply the continuing evolution of ABA responses in Brassica since its divergence from a common ancestor, involving both protein-coding and non-coding nucleotide sequences. Together, our results will provide a basis for developing strategies for molecular manipulation of drought tolerance in crop plants.

Overexpression of CRK4, the cysteine-rich receptor-like protein kinase of Arabidopsis, regulates the resistance to abiotic stress and abscisic acid responses

Overexpression of CRK4, the cysteine-rich receptor-like protein kinase of Arabidopsis, regulates the resistance to abiotic stress and abscisic acid responses

Contrasted NCED gene expression across conifers with rising and peaking abscisic acid responses to drought

Conifer trees have diverse strategies to cope with drought. They accumulate the plant hormone abscisic acid (ABA) following a range of profiles from constantly rising to peaking and falling (R- and P-type) with direct effect on foliar transpiration. The molecular basis of this adaptive diversification among species is largely unknown. Here, we analysed the sequences of candidate ABA biosynthesis and catabolism genes and monitored their expression in response to intensifying drought. We studied young trees from Cupressaceae, Pinaceae, and Taxaceae under controlled drought conditions and compared changes in water status, ABA profiles and gene-specific transcript levels. Our data indicate that R-type and P-type ABA profiles may be controlled by divergent expression of genes involved in the biosynthetic and catabolic pathways of ABA, respectively, and emphasize a key role of nine-cis-epoxycarotenoid dioxygenases (NCED) genes. Our results open the doors to understanding the molecular basis of contrasted drought response strategies across conifer taxa, which we expect will help foresters grow more drought-resilient trees.

The OsGAPC1-OsSGL module negatively regulates salt tolerance by mediating abscisic acid biosynthesis in rice.

Plants frequently encounter adverse conditions and stress during their lives. Abscisic acid (ABA) plays a crucial role in response to salt stress, and dynamic regulation of ABA levels is essential for plant growth and stress resistance. In this study, we identified a transcription factor, OsSGL (Oryza sativa Stress tolerance and Grain Length), which acts as a negative regulator in salt stress, controlling ABA synthesis. OsSGL-overexpressing and mutant materials exhibited sensitivity and tolerance to salt stress, respectively. Notably, under salt treatment, several ABA-related genes, including the ABA synthesis enzyme OsNCED3 and the ABA response gene OsRAB21, were bound by OsSGL, leading to the inhibition of their transcription. Additionally, we found that a key enzyme involved in glycolysis, OsGAPC1, interacted with OsSGL and enhanced the inhibitory effect of OsSGL on OsNCED3. Upon salt stress, OsGAPC1 underwent acetylation and then translocated from the nucleus to the cytoplasm, partially alleviating the inhibitory effect of OsSGL on OsNCED3. Identification of the OsGAPC1-OsSGL module revealed a negative regulatory mechanism involved in the response of rice to salt stress. This discovery provides insight into the dynamic regulation of ABA synthesis in plants under salt stress conditions, highlighting the delicate balance between stress resistance and growth regulation.

MAPKKK28 functions upstream of the MKK1-MPK1 cascade to regulate abscisic acid responses in rice.

The mitogen-activated protein kinase (MAPK) cascade (MAPKKK-MAPKK-MAPK) plays a critical role in biotic and abiotic stress responses and abscisic acid (ABA) signalling. A previous study has shown that the ABA-activated MKK1-MPK1 cascade is essential in regulating ABA response and stress tolerance in rice. However, the specific MAPKKK upstream of the MKK1-MPK1 cascade in ABA signalling remains unknown. Here, we identified that MAPKKK28, a previously uncharacterized member of the rice MEKK family, is involved in regulating ABA responses, including seed germination, root growth, stomatal closure, and the tolerance to oxidative stress and osmotic stress. We found that MAPKKK28 directly interacts with and phosphorylates MKK1. Further analysis indicated that the activation of both MKK1 and MPK1 depends on MAPKKK28 in ABA signalling. Genetic analysis revealed that MAPKKK28 functions upstream of the MKK1-MPK1 cascade to positively regulate ABA responses and enhance tolerance to oxidative and osmotic stress. These results not only reveal a new complete MAPK cascade in plants but also uncover its importance in ABA signalling.