Abscisic Acid Response Research Articles

R3-MYB proteins OsTCL1 and OsTCL2 modulate seed germination via dual pathways in rice

Salt and drought stress are common abiotic factors that exert a detrimental influence on seed germination, potentially leading to significantly impaired growth and production in rice. Gaining a comprehensive understanding of the molecular response of seeds to abiotic stress during the germination is of paramount importance. In the present study, we identified two R3-MYB genes in rice, namely OsTCL1 and OsTCL2, and characterized their roles in regulating seed germination under salt and drought stress. Plants with tcl1 and tcl2 mutant alleles exhibited delayed seed germination, particularly under stress conditions. The tcl1 tcl2 double mutant showed an even more pronounced reduction in germination during initial stages of germination, thereby indicating a redundant regulatory function of OsTCL1 and OsTCL2 in seed germination under abiotic stresses. Furthermore, we demonstrated that the transcript levels of several phospholipase D (PLD) genes were downregulated in the tcl1 tcl2 mutant, resulting in a decreased level of the phosphatidic acid (PA) product. Application of 1-butanol, a competitive substrate inhibitor of PLD-dependent production of PA, attenuated the stress response of the tcl1 tcl2 mutant. This suggests that OsTCL1 and OsTCL2 partially modulate seed germination through the PLD-PA signaling pathway. Moreover, there were alterations in the expression of genes involved in abscisic acid (ABA) biosynthesis, metabolism and signaling transduction in the double mutant. These changes affected the endogenous ABA level and ABA response, thereby influencing seed germination. Application of both 1-butanol and ABA synthesis inhibitor sodium tungstate (Na2WO4) nearly eliminated the differences in stress response between wild type and the tcl1 tcl2 mutant. This indicates that OsTCL1 and OsTCL2 synergistically coordinate seed germination under abiotic stresses through both the PLD-PA signaling and ABA-mediated pathways.

Differential gene expression during floral transition in pineapple.

Pineapple (Ananas comosus var. comosus) and ornamental bromeliads are commercially induced to flower by treatment with ethylene or its analogs. The apex is transformed from a vegetative to a floral meristem and shows morphological changes in 8 to 10days, with flowers developing 8 to 10weeks later. During eight sampling stages ranging from 6h to 8days after treatment, 7961 genes were found to exhibit differential expression (DE) after the application of ethylene. In the first 3days after treatment, there was little change in ethylene synthesis or in the early stages of the ethylene response. Subsequently, three ethylene response transcription factors (ERTF) were up-regulated and the potential gene targets were predicted to be the positive flowering regulator CONSTANS-like 3 (CO), a WUSCHEL gene, two APETALA1/FRUITFULL (AP1/FUL) genes, an epidermal patterning gene, and a jasmonic acid synthesis gene. We confirm that pineapple has lost the flowering repressor FLOWERING LOCUS C. At the initial stages, the SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) was not significantly involved in this transition. Another WUSCHEL gene and a PHD homeobox transcription factor, though not apparent direct targets of ERTF, were up-regulated within a day of treatment, their predicted targets being the up-regulated CO, auxin response factors, SQUAMOSA, and histone H3 genes with suppression of abscisic acid response genes. The FLOWERING LOCUS T (FT), TERMINAL FLOWER (TFL), AGAMOUS-like APETELAR (AP2), and SEPETALA (SEP) increased rapidly within 2 to 3days after ethylene treatment. Two FT genes were up-regulated at the apex and not at the leaf bases after treatment, suggesting that transport did not occur. These results indicated that the ethylene response in pineapple and possibly most bromeliads act directly to promote the vegetative to flower transition via APETALA1/FRUITFULL (AP1/FUL) and its interaction with SPL, FT, TFL, SEP, and AP2. A model based on AP2/ERTF DE and predicted DE target genes was developed to give focus to future research. The identified candidate genes are potential targets for genetic manipulation to determine their molecular role in flower transition.

The Arabidopsis ubiquitin ligases ATL31 and ATL6 regulate plant response to salt stress in an ABA-independent manner

E3 ubiquitin ligases play critical roles in regulating plant response to salt stress. Arabidopsis Tóxicos En Levadura (ATL) is a subfamily of RING-type E3 ubiquitin ligases widely conserved in plant species. ATL genes have been shown to be involved in regulating plant response to biotic or abiotic stresses. We previously found that a pair of ATL genes, ATL31 and ATL6 positively regulated plant innate immunity. However, whether ATL31/6 are also involved in salt stress response remains to be investigated. Here, we demonstrate that ATL31/6 are induced by salt stress. The atl31 atl6 double mutant exhibits increased salt tolerance compared to the wild-type plants, while transgenic plants overexpressing ATL31 are more salt-sensitive. Notably, ATL31 and ATL6 do not participate in the abscisic acid (ABA) response. Furthermore, NaCl treatment induces the proteasomal degradation of ATL31 proteins. Together, we demonstrate that ATL31/6 positively regulate plant tolerance to salt stress, which is independent of ABA, and our work reveals that ATL31/6 are involved in regulating plant response to both biotic and abiotic stress.

The peroxidase gene OsPrx114 activated by OsWRKY50 enhances drought tolerance through ROS scavenging in rice

Drought is among the most severe environmental stressors, imposing detrimental effects on plant growth and development. In this study, we have identified a class III peroxidase gene, OsPrx114, which was induced under PEG (Polyethylene glycol) and drought conditions and found to be localized in both the plasma membrane and endoplasmic reticulum. The promoter region of OsPrx114 encompasses cis-elements, including ABRE (ABA response elements), MBS (MYB binding elements), and W-box, which are likely contributors to drought tolerance. In comparison to Nipponbare (Nip) plants, the overexpression of OsPrx114 enhanced drought tolerance by reducing the accumulation of reactive oxygen species (ROS) through the upregulation of enzyme activities, such as peroxide dismutase (POD) and catalase (CAT). This was accompanied by an increase in proline (Pro) content and a decrease in malondialdehyde (MDA) content. Furthermore, a series of assays including yeast one-hybrid, electrophoretic mobility shift, and dual luciferase assays, demonstrated that the transcription factor OsWRKY50 binds to the W-box (TTGACC) within the promoter of OsPrx114, thereby activating its transcription. OsWRKY50 plays a positive role in regulating OsPrx114-mediated drought resistance by mitigating ROS accumulation in rice. These findings offer a molecular foundation for comprehending the function of the OsWRKY50-OsPrx114 module in response to drought stress in rice.

Comparative Analysis of Phospholipase D (PLD) Gene Family in Camelina sativa and Brassica napus and Its Responses in Camelina Seedlings under Salt Stress

Phospholipases are among the important elements involved in lipid-dependent cell signaling that lead to the induction of downstream pathways. In the current study, phospholipases D (PLDs) gene family was characterized and compared in two important oilseed crops, Brassica napus and Camelina sativa. The results revealed that PLD has 33 members in Camelina sativa (CsPLD) and 41 members in Brassica napus (BnPLD). All studied PLDs showed a negative GRAVY value, indicating that PLDs are probably hydrophilic proteins. Phylogenetic analysis classified PLDs into five main subfamilies, including gamma, delta, beta, alpha, and zeta. According to evolution analysis, a different evolution process was observed between CsPLD and BnPLD. In addition, the results disclosed that most of the PLD genes have been segmentally duplicated under purifying selection. Cis-regulatory elements related to ABA and auxin responsiveness were found more in the upstream region of CsPLDs, while elements linked with MeJA responsiveness were observed more in the promoter region of BnPLDs. Analysis of the expression data showed that PLD alpha genes have a wide expression in most tissues. Quantitative expression analysis (qPCR) of CsPLD genes under salt stress, 200 mM of NaCl, was conducted in different time series. The results revealed that the CsPLD genes are involved in the response to salinity stress and their expression levels enhance with increasing salinity stress period. The outcomes of this research will be useful for future molecular works related to lipid signaling in oilseed plants.

Genome-wide identification of DUF506 gene family in Oryzasativa and expression profiling under abiotic stresses.

The domain of unknown function 560 (DUF560), also known as the PDDEXK_6 family, is a ubiquitous plant protein that has been confirmed to play critical roles in Arabidopsis root development as well as ABA and abiotic responses. However, genome-wide identification and expression pattern analysis in rice (Oryza sativa) still need to be improved. Based on the phylogenetic relationship, 10 OsDUF506 genes were identified and classified into four subfamilies. Segmental duplication was essential to the expansion of OsDUF506s, which were subjected to purifying selective pressure. Except for OsDUF50609 and OsDUF50610, the OsDUF506s shared colinear gene pairs with five monocot species, showing that they were conserved in evolution. Furthermore, the conserved domains, gene structures, SNPs distribution, and targeting miRNAs were systematically investigated. Massive cis-regulatory elements were discovered in promoter regions, implying that OsDUF506s may be important in hormone regulation and abiotic stress response. Therefore, we analyzed plant hormone-induced transcriptome data and performed qRT-PCR on eight OsDUF506s under drought, cold, and phosphorus-deficient stresses. The results revealed that most OsDUF506s respond to ABA and JA treatment, as well as drought and cold conditions. In conclusion, our findings provided insights into the evolution and function of OsDUF506s, which could benefit crop breeding in the future.

Expression of maize OXS2a in Arabidopsis stunts plant growth but enhances heat tolerance

As plants encounter various environmental stresses, judicial allocation of resources to stress response is crucial for plant fitness. The plant OXS2 (OXIDATIVE STRESS 2) family has been reported to play important roles in growth regulation and stress response. Here, we report that the maize OXS2 family member ZmOXS2a when expressed in Arabidopsis retards growth including delayed flowering, but improves heat tolerance. ZmOXS2a can be found in the cytoplasm, nucleus and PBs/P bodies (mRNA processing bodies), but heat treatment induces higher accumulation in the PBs. Deletion of ARR (arginine rich region) and TZF (tandem zinc finger) domains for high-affinity RNA-binding reduced PBs accumulation of ZmOXS2a; and unlike ZmOXS2a, expression of this deletion mutant gene affected neither Arabidopsis growth nor heat tolerance. This suggests that ZmOXS2a might be involved in RNA degradation, which would also account for the larger amount of down-regulated genes found in ZmOXS2a expressing lines. Furthermore, 240 of 890 down-regulated genes contain ARE (AU-rich elements) in the mRNA 3′UTR that might be potential targets of ZmOXS2a. Expression of ZmOXS2a also disturbs the response to ABA (abscisic acid) and cytokinin, as GO (gene ontology) analysis shows that 50 and 15 DEGs (differentially expressed genes) are enriched in the GO term for ABA and cytokinin responses, respectively. ZmOXS2a expression lines are more sensitive to ABA, but less sensitive to cytokinin. It is likely that ZmOXS2a promotes the degradation of the mRNA of down-regulated genes containing ARE, which consequently perturbs the hormone pathways that affect stress response-related plant growth.

Suppression of SlDREB3 increases leaf ABA responses and promotes drought tolerance in transgenic tomato plants

Drought susceptibility is a major yield limiting factor in agricultural crops especially in hybrids/varieties that have been bred for high yields. We show that manipulation of the SlDREB3 gene in tomato alters ABA responses and thereby sensitivity of stomatal closure to ABA. SlDREB3 suppression lines show ABA hypersensitivity and rapid stomatal closure in response to ABA while over-expression lines show reduced sensitivity to ABA and open stomata even at high ABA levels with rapid water loss after 10 days of water stress. This is accompanied with high ROS levels and increased membrane damage due to senescence of leaves and drastically reduced survival in drought. The relative water content (RWC) of OEx lines is much reduced even when grown under well-watered conditions. In contrast, suppression lines show greater tolerance to water stress and almost complete survival to 10-day water stress. They show much reduced ROS levels, reduced membrane damage, higher RWC and reduced leaf water loss. These changes are associated with higher expression of ABA signalling pathway genes in suppression lines while these are highly reduced in OEx lines. The studies suggest that control of ABA signalling by SlDREB3 can help in withstanding severe drought.

GhIMP10D, an inositol monophosphates family gene, enhances ascorbic acid and antioxidant enzyme activities to confer alkaline tolerance in Gossypium hirsutum L.

BackgroundInositol monophosphates (IMP) are key enzymes in the ascorbic acid (AsA) synthesis pathways, which play vital roles in regulating plant growth and development and stresses tolerance. To date, no comprehensive analysis of the expression profile of IMP genes and their functions under abiotic stress in cotton has been reported.ResultsIn this study, the genetic characteristics, phylogenetic evolution, cis-acting elements and expression patterns of IMP gene family in cotton were systematically analyzed. A total of 28, 27, 13 and 13 IMP genes were identified in Gossypium hirsutum (G. hirsutum), Gossypium barbadense (G. barbadense), Gossypium arboreum (G. arboreum), and Gossypium raimondii (G. raimondii), respectively. Phylogenetic analysis showed that IMP family genes could cluster into 3 clades. Structure analysis of genes showed that GhIMP genes from the same subgroup had similar genetic structure and exon number. And most GhIMP family members contained hormone-related elements (abscisic acid response element, MeJA response element, gibberellin response element) and stress-related elements (low temperature response element, defense and stress response element, wound response element). After exogenous application of abscisic acid (ABA), some GhIMP genes containing ABA response elements positively responded to alkaline stress, indicating that ABA response elements played an important role in response to alkaline stress. qRT-PCR showed that most of GhIMP genes responded positively to alkaline stress, and GhIMP10D significantly upregulated under alkaline stress, with the highest up-regulated expression level. Virus-induced gene silencing (VIGS) experiment showed that compared with 156 plants, MDA content of pYL156:GhIMP10D plants increased significantly, while POD, SOD, chlorophyII and AsA content decreased significantly.ConclusionsThis study provides a thorough overview of the IMP gene family and presents a new perspective on the evolution of this gene family. In particular, some IMP genes may be involved in alkaline stress tolerance regulation, and GhIMP10D showed high expression levels in leaves, stems and roots under alkaline stress, and preliminary functional verification of GhIMP10D gene suggested that it may regulate tolerance to alkaline stress by regulating the activity of antioxidant enzymes and the content of AsA. This study contributes to the subsequent broader discussion of the structure and alkaline resistance of IMP genes in cotton.

Genome-wide identification and expression analysis of PtJAZ gene family in poplar (Populus trichocarpa)

BackgroundThe jasmonate ZIM domain (JAZ) protein is a key repressor of the jasmonate signal transduction pathway, which plays an important role in plant growth and development and defense responses. In this study, based on the published whole-genome data, we identified members of the JAZ gene family in Populus trichocarpa. Through a series of bioinformatic approaches, their expression patterns under various stress conditions have been analyzed to explore and excavate the endogenous resistance genes of poplar and provide a theoretical basis for breeding new varieties of poplar resistance.ResultsA total of 13 PtJAZ genes have been identified in P. trichocarpa and designated as PtJAZ1–PtJAZ13. Those 13 PtJAZ genes were unevenly distributed on nine chromosomes, and they could be divided into four subfamilies. The gene structures and motif composition of the members derived from the same subfamily were similar. Collinearity analysis demonstrated that, compared with Arabidopsis thaliana and Oryza sativa, the most collinear pairs (13) were found in P. trichocarpa and Eucalyptus robusta. Cis-acting element analysis suggested that the promoter regions of PtJAZs contained a large number of hormones and stress response elements, of which abscisic acid (ABA) and methyl jasmonate (MeJA) hormone response elements were the most abundant. The PtJAZ genes not only had diverse expression patterns in different tissues, but they also responded to various abiotic and biotic stress conditions. The co-expression network and GO and KEGG analyses showed that JAZ genes were closely related to insect resistance.ConclusionsIn this study, applying bioinformatic methods, 13 PtJAZ gene family members from P. trichocarpa were identified and comprehensively analyzed. By further studying the function of the poplar JAZ gene family, the aim is to select genes with better insect resistance and stress resistance so as to lay a solid foundation for the subsequent breeding of new poplar varieties.

SUPPRESSOR OF MAX2 LIKE 6, 7, and 8 Interact with DDB1 BINDING WD REPEAT DOMAIN HYPERSENSITIVE TO ABA DEFICIENT 1 to Regulate the Drought Tolerance and Target SUCROSE NONFERMENTING 1 RELATED PROTEIN KINASE 2.3 to Abscisic Acid Response in Arabidopsis.

SUPPRESSOR OF MAX2-LIKE 6, 7, and 8 (SMXL6,7,8) function as repressors and transcription factors of the strigolactone (SL) signaling pathway, playing an important role in the development and stress tolerance in Arabidopsis thaliana. However, the molecular mechanism by which SMXL6,7,8 negatively regulate drought tolerance and ABA response remains largely unexplored. In the present study, the interacting protein and downstream target genes of SMXL6,7,8 were investigated. Our results showed that the substrate receptor for the CUL4-based E3 ligase DDB1-BINDING WD-REPEAT DOMAIN (DWD) HYPERSENSITIVE TO ABA DEFICIENT 1 (ABA1) (DWA1) physically interacted with SMXL6,7,8. The degradation of SMXL6,7,8 proteins were partially dependent on DWA1. Disruption of SMXL6,7,8 resulted in increased drought tolerance and could restore the drought-sensitive phenotype of the dwa1 mutant. In addition, SMXL6,7,8 could directly bind to the promoter of SUCROSE NONFERMENTING 1 (SNF1)-RELATED PROTEIN KINASE 2.3 (SnRK2.3) to repress its transcription. The mutations in SnRK2.2/2.3 significantly suppressed the hypersensitivity of smxl6/7/8 to ABA-mediated inhibition of seed germination. Conclusively, SMXL6,7,8 interact with DWA1 to negatively regulate drought tolerance and target ABA-response genes. These data provide insights into drought tolerance and ABA response in Arabidopsis via the SMXL6,7,8-mediated SL signaling pathway.

Loss of ACO4 in petunia improves abiotic stress tolerance by reducing the deleterious effects of stress-induced ethylene

To investigate the role of ethylene (ET) in abiotic stress tolerance in petunia cv. ‘Mirage Rose’, petunia plants in which the ET biosynthesis gene 1-aminocyclopropane-1-carboxylic acid oxidase 4 (ACO4) was knocked out (phaco4 mutants) and wild-type (WT) plants were exposed to heat and drought conditions. Loss of function of ACO4 significantly delayed leaf senescence and chlorosis under heat and drought stress by maintaining the SPAD values and the relative water content, indicating a greater stress tolerance of phaco4 mutants than that of WT plants. This tolerance was related to the lower ET and reactive oxygen species levels in the mutants than in WT plants. Furthermore, the stress-induced expression of genes related to ET signal transduction, antioxidant and proline activities, heat response, and biosynthesis of abscisic acid was higher in the mutants than in WT plants, indicating a greater stress tolerance in the former than in the latter. These results demonstrate the deleterious effects of stress-induced ET on plant growth and provide a better physiological and molecular understanding of the role of stress ET in the abiotic stress response of petunia. Because the loss of function of ACO4 in petunia improved stress tolerance, we suggest that ACO4 plays a vital role in stress-induced leaf senescence and acts as a negative regulator of abiotic stress tolerance.

Genome-Wide Identified MADS-Box Genes in Prunus campanulata 'Plena' and Theirs Roles in Double-Flower Development.

The MADS-box gene family plays key roles in flower induction, floral initiation, and floral morphogenesis in flowering plants. To understand their functions in the double-flower formation of Prunus campanulata 'Plena' (hereafter referred to as PCP), which is an excellent flowering cherry cultivar, we performed genome-wide identification of the MADS-box gene family. In this study, 71 MADS-box genes were identified and grouped into the Mα, Mβ, Mγ and MIKC subfamilies according to their structures and phylogenetic relationships. All 71 MADS-box genes were located on eight chromosomes of PCP. Analysis of the cis-acting elements in the promoter region of MADS-box genes indicated that they were associated mainly with auxin, abscisic acid, gibberellin, MeJA (methyl jasmonate), and salicylic acid responsiveness, which may be involved in floral development and differentiation. By observing the floral organ phenotype, we found that the double-flower phenotype of PCP originated from petaloid stamens. The analysis of MIKC-type MADS-box genes in PCP vegetative and floral organs by qRT-PCR revealed six upregulated genes involved in petal development and three downregulated genes participating in stamen identity. Comparative analysis of petaloid stamens and normal stamens also indicated that the expression level of the AG gene (PcMADS40) was significantly reduced. Thus, we speculated that these upregulated and downregulated genes, especially PcMADS40, may lead to petaloid stamen formation and thus double flowers. This study lays a theoretical foundation for MADS-box gene identification and classification and studying the molecular mechanism underlying double flowers in other ornamental plants.

Drought tolerance mechanisms in chickpea (Cicer arietinum L.) investigated by physiological and transcriptomic analysis

Chickpea is a grain legume that enhances soil fertility and represents an important source of green proteins for human health. It is typically cultivated in marginal areas with limited water availability. The aim of this study was to shed light into the molecular mechanisms of drought tolerance of this legume. First, the physiological response of nine stable genotype lines in control and drought-stress conditions was assessed. Two of these genotypes (Desi PI5980808 and Kabuli Flip07 318 C) showed opposite physiological responses to drought stress. Desi PI5980808 displayed a reduced chlorophyll content and an unaltered concentration of osmolytes (proline and soluble sugars) under drought stress. Kabuli Flip07 318 C did not show any reduction in photosynthesis and chlorophyll content, but a significant increase of proline and soluble sugars was observed under the drought stress. To identify genes and molecular mechanisms involved in drought tolerance, RNA-seq was performed in control conditions and after one week of drought stress in these two contrasting genotypes. The genotype with higher drought sensitivity showed more intense changes in gene expression than the genotype with less sensitivity, up-regulating genes involved in photophosphorylation process (transferases, oxygen lyases and oxidoreductases), hormones (brassinosteroids, abscisic acid and gibberellin response), solute transporters, nutrient uptake, and cell wall properties (cellulose synthases, hemicellulose synthases, poligalacturonases, pectate lyases). Small number of up-regulated genes in the genotype with lower drought sensitivity included those involved in chromatin modifications. These results will be helpful for further studies aiming at identifying genes and molecular markers to be used in breeding strategies to develop chickpea cultivars more resilient to water stress.

Pathogen Xanthomonas campestris-induced immune-related genes integrated with phytohormones are involved in stomatal closure by interactively regulating ROS and Ca2+ signaling in the Xcc–Brassica napus pathosystem

This study aimed to characterize Xanthomonas campestris pv. campestris (Xcc)-induced ABA interaction with immune-related genes in stomatal movement. Xcc-responsive alterations in resistance genes, Ca2+, reactive oxidative species, and phytohormones were compared with those of exogenous ABA application (Exo-ABA) as being linked to stomatal movement. Xcc infection up-regulated botrytis-induced kinase 1 (BIK1) with a significant increase in salicylic acid (SA) and jasmonic acid (JA) levels at the early phase of infection (2 days after post-inoculation; DPI), this treatment also increased TIR-NB-LRR-type R-gene (TAO1) and R-gene–mediated signaling gene (SGT1) expression as well as SA and ABA accumulation during the later phase (7–15 DPI). In contrast, the Exo-ABA treatment did not activate these genes, even though the ABA-receptor gene PYR1 was up-regulated. The accumulation of Ca2+ and H2O2 in Xcc-inoculated leaves resulted from the activation of calcium-dependent protein kinase 5 (CDPK5), SA synthesis and signaling genes (ICS1 and NPR1), and ABA-related genes (NCED3 and MYC2), while in Exo-ABA treated leaves via the activation of H2O2-related genes (NADPH oxidase and OXI1) and calmodulin (CaM) in predominant ABA responses, leading to a depression of SA responses. Furthermore, the expression of immune-responsive mitogen-activated protein kinase 3 (MAPK3) was prominent in Xcc-inoculated leaves, while MAPK9 was more prominently expressed in Exo-ABA-treated leaves. Both Xcc infection and Exo-ABA treatments led to stomatal closure, accompanied by enhanced expression of slow anion channel 1 (SLAC1). These results indicate that Xcc-induced BIK1-SA-JA interaction acts as pattern-triggered immunity (PTI) in the early phase, and then after which TAO1-SA-ABA mediates CDPK5-dependent Ca2+ and H2O2 generation, leading to MAPK3-SLAC1-mediated stomatal closure in the later phase, while in Exo-ABA-treated leaves via ABA-mediated CaM-dependent H2O2 accumulation and stomata closure.

Novel Compounds Derived from DFPM Induce Root Growth Arrest through the Specific VICTR Alleles of Arabidopsis Accessions.

The small compound [5-(3,4-dichlorophenyl) furan-2-yl]-piperidine-1-ylmethanethione (DFPM) inhibits ABA responses by activating effector-triggered immune signal transduction in Arabidopsis. In addition to the known function of DFPM as an antagonist of ABA signaling, DFPM causes accession-specific root growth arrest in Arabidopsis Columbia-0 via the TIR-NLR protein VICTR (VARIATION IN COMPOUND TRIGGERED ROOT growth response) in an EDS1/PAD4/RAR1/SGT1B-dependent manner. Although DFPM could control the specific steps of various cellular responses, the functional residues for the activity of DFPM or the existence of a stronger version of DFPM modification have not been characterized thoroughly. This study analyzed twenty-two DFPM derivatives during root growth arrest, inhibition of ABA signaling, and induction of biotic signal transduction to determine critical residues that confer the specific activity of DFPM. Furthermore, this study identified two more Arabidopsis accessions that generate significant root growth arrest in response to DFPM derivatives dependent on multiple amino acid polymorphisms in the coding region of VICTR. The isolation of novel compounds, such as DFPM-5, and specific amino acid polymorphisms critical for the compound-induced responses will help determine the detailed regulatory mechanism for how DFPM regulates abiotic and biotic stress signaling interactions.

Genome-wide identification and molecular evolution of NAC gene family in Dendrobium nobile.

NAC transcription factors are an important genes that regulate plant growth and development, and can regulate functions such as fruit ripening in plants. Based on genome data of Dendrobium nobile, the NAC gene family was identified and analyzed by bioinformatics methods. In this study, we identified 85 NAC genes in Dendrobium nobile genome, and systematically analyzed the NAC gene family. We found that they were distributed unevenly in the nineteen chromosomes. The amino acid length of D. nobile NAC gene family (DnoNACs) ranged from 80 to 1065, molecular weight ranged from 22.17 to 119.02 kD, and isoelectric point ranged from 4.61~9.26. Its promoter region contains multiple stress responsive elements, including light responsive, gibberellin-responsive, abscisic acid responsiveness, MeJA-responsiveness and drought-inducibility elements. Phylogenetic analysis indicates that the D. nobile NAC gene family is most closely related to Dendrobium catenatum and Dendrobium chrysotoxum. Analysis of SSR loci indicates that the fraction of mononucleotide repeats was the largest, as was the frequency of A/T. Non-coding RNA analysis showed that these 85 NAC genes contain 397 miRNAs. The collinearity analysis shows that 9 collinear locis were found on the chromosomes of D. nobile with Arabidopsis thaliana, and 75 collinear locis with D.chrysotoxum. QRT-PCR experiment under different salt concentration and temperature conditions verified the response mechanism of DnoNAC gene family under stress conditions. Most DnoNAC genes are sensitive to salt stress and temperature stress. The results of this study provide a reference for further understanding the function of NAC gene in D. nobile.

Coordination of growth and drought responses by GA-ABA signaling in rice.

The drought caused by global warming seriously affects the crop growth and agricultural production. Plants have evolved distinct strategies to cope with the drought environment. Under drought stress, energy and resources should be diverted from growth toward stress management. However, the molecular mechanism underlying coordination of growth and drought response remains largely elusive. Here, we discovered that most of the gibberellin (GA) metabolic genes were regulated by water scarcity in rice, leading to the lower GA contents and hence inhibited plant growth. Low GA contents resulted in the accumulation of more GA signaling negative regulator SLENDER RICE 1, which inhibited the degradation of abscisic acid (ABA) receptor PYL10 by competitively binding to the co-activator of anaphase-promoting complex TAD1, resulting in the enhanced ABA response and drought tolerance. These results elucidate the synergistic regulation of crop growth inhibition and promotion of drought tolerance and survival, and provide useful genetic resource in breeding improvement of crop drought resistance.

Exploring the Heat Shock Transcription Factor (HSF) Gene Family in Ginger: A Genome-Wide Investigation on Evolution, Expression Profiling, and Response to Developmental and Abiotic Stresses.

Ginger is a valuable crop known for its nutritional, seasoning, and health benefits. However, abiotic stresses, such as high temperature and drought, can adversely affect its growth and development. Heat shock transcription factors (HSFs) have been recognized as crucial elements for enhancing heat and drought resistance in plants. Nevertheless, no previous study has investigated the HSF gene family in ginger. In this research, a total of 25 ZoHSF members were identified in the ginger genome, which were unevenly distributed across ten chromosomes. The ZoHSF members were divided into three groups (HSFA, HSFB, and HSFC) based on their gene structure, protein motifs, and phylogenetic relationships with Arabidopsis. Interestingly, we found more collinear gene pairs between ZoHSF and HSF genes from monocots, such as rice, wheat, and banana, than dicots like Arabidopsis thaliana. Additionally, we identified 12 ZoHSF genes that likely arose from duplication events. Promoter analysis revealed that the hormone response elements (MEJA-responsiveness and abscisic acid responsiveness) were dominant among the various cis-elements related to the abiotic stress response in ZoHSF promoters. Expression pattern analysis confirmed differential expression of ZoHSF members across different tissues, with most showing responsiveness to heat and drought stress. This study lays the foundation for further investigations into the functional role of ZoHSFs in regulating abiotic stress responses in ginger.

Antagonistic Regulation of ABA Responses by Duplicated Tandemly Repeated DUF538 Protein Genes in Arabidopsis.

The plant hormone ABA (abscisic acid) regulates plant responses to abiotic stresses by regulating the expression of ABA response genes. However, the functions of a large portion of ABA response genes have remained unclear. We report in this study the identification of ASDs (ABA-inducible signal peptide-containing DUF538 proteins), a subgroup of DUF538 proteins with a signal peptide, as the regulators of plant responses to ABA in Arabidopsis. ASDs are encoded by four closely related DUF538 genes, with ASD1/ASD2 and ASD3/ASD4 being two pairs of duplicated tandemly repeated genes. The quantitative RT-PCR (qRT-PCR) results showed that the expression levels of ASDs increased significantly in response to ABA as well as NaCl and mannitol treatments, with the exception that the expression level of ASD2 remained largely unchanged in response to NaCl treatment. The results of Arabidopsis protoplast transient transfection assays showed that ASDs were localized on the plasma membrane and in the cytosol and nucleus. When recruited to the promoter of the reporter gene via a fused GD domain, ASDs were able to slightly repress the expression of the co-transfected reporter gene. Seed germination and cotyledon greening assays showed that ABA sensitivity was increased in the transgenic plants that were over-expressing ASD1 or ASD3 but decreased in the transgenic plants that were over-expressing ASD2 or ASD4. On the other hand, ABA sensitivity was increased in the CRISPR/Cas9 gene-edited asd2 single mutants but decreased in the asd3 single mutants. A transcriptome analysis showed that differentially expressed genes in the 35S:ASD2 transgenic plant seedlings were enriched in several different processes, including in plant growth and development, the secondary metabolism, and plant hormone signaling. In summary, our results show that ASDs are ABA response genes and that ASDs are involved in the regulation of plant responses to ABA in Arabidopsis; however, ASD1/ASD3 and ASD2/ASD4 have opposite functions.