Project description:The OsbZIP23 transcription factor has been characterized for its essential role in drought resistance in rice, but the mechanism is unknown. Here, we performed genome-wide identification of OsbZIP23 targets by immunoprecipitation sequencing (ChIP-seq) and RNA Sequencing (RNA-Seq) analyses in the OsbZIP23-overexpression, osbzip23 mutant, and wild-type rice under normal and drought stress conditions. OsbZIP23 directly regulates a large number of reported genes that function in stress response, hormone signaling, and developmental processes. Among these targets, we found that OsbZIP23 could positively regulate OsPP2C49, and overexpression of OsPP2C49 in rice resulted in significantly decreased sensitivity of the ABA response and rapid dehydration. Moreover, OsNCED4 (9-cis-epoxycarotenoid dioxygenase 4), a key gene in ABA biosynthesis, was also positively regulated by OsbZIP23. Together, our results suggest that OsbZIP23 acts as a central regulator in ABA signaling and biosynthesis, and drought resistance in rice.
Project description:Responses to drought in rice are regulated by transcription factor OsbZIP46 via ABA signaling. This work characterizes a protein MODD that negatively regulates OsbZIP46 activity and stability through HDAC-related chromatin remodeling and OsPUB70-mediated ubiquitination, respectively, to fine tune ABA signaling and drought resistance.
Project description:Responses to drought in rice are regulated by transcription factor OsbZIP46 via ABA signaling. This work characterizes a protein MODD that negatively regulates OsbZIP46 activity and stability through HDAC-related chromatin remodeling and OsPUB70-mediated ubiquitination, respectively, to fine tune ABA signaling and drought resistance. Examination of mRNA levels in modd mutants and wild type plants under normal condition.
Project description:Drought stress can cause huge crop production losses. Drought resistance consists of complex traits, and is regulated by arrays of unclear networks at the molecular level. A stress-responsive NAC transcription factor gene SNAC1 has been reported for its function in the positive regulation of drought resistance in rice, and several downstream SNAC1 targets have been identified. However, a complete regulatory network mediated by SNAC1 in drought response remains unknown. In this study, we performed Chromatin immunoprecipitation sequencing (ChIP-Seq) and RNA-Seq of SNAC1-overexpression transgenic rice (SNAC1-OE) lines and wild-type under normal and moderate drought stress conditions, to identify all SNAC1 target genes at a genome-wide scale by RNA-Seq analyses. We detected 980 differentially expressed genes (DEGs) in the SNAC1-OE lines compared to the wild-type control under drought stress conditions. By ChIP-Seq analyses, we identified 4,339 SNAC1-binding genes under drought stress conditions (SNAC1BGDs). By combining the DEGs and SNAC1BGDs, we identified 93 SNAC1-targeted genes involved in drought responses (SNAC1TGDs). Most SNAC1TGDs are involved in transcriptional regulation, response to water loss, and other processes related to stress responses. Moreover, the major motifs in the SNAC1BGDs promoters include a NAC recognition sequence (NACRS) and an ABA responsive element (ABRE). SNAC1-OE lines are more sensitive to ABA than wild-type. SNAC1 can bind to the OsbZIP23 promoter, an important ABA signaling regulator, and positively regulate the expression of several ABA signaling genes.
Project description:Histone H2B monoubiquitination (H2Bub1) has been implicated in several important physiological and developmental processes, but its role in the regulation of stress responses remains elusive. Here, we report that H2Bub1 is crucially involved in abscisic acid (ABA) signaling and drought response in rice. We found the rice (Oryza sativa) HISTONE MONOUBIQUITINATION2 (OsHUB2), an E3 ligase for H2Bub1, interacted with OsbZIP46, a key transcription factor regulating ABA signaling and drought response in rice. Genetic analyses suggest that OsHUB2, induced by drought and ABA, positively modulates ABA sensitivity and drought resistance. The H2Bub1 levels were increased in the promoters of OsbZIP46 target genes under the drought stress and ABA treatments, and the increased H2Bub1 levels were positively correlated to the increased expression levels of the target genes. Interestingly, MODD, a reported suppressor of ABA signaling and drought resistance through mediation of OsbZIP46 deactivation and degradation, can repress the H2Bub1 level in the promoters of OsbZIP46 target genes by recruiting a putative deubiquitinase OsOTLD1. Suppression of OsOTLD1 in vivo resulted in increased H2Bub1 levels and expression of drought-responsive genes targeted by OsbZIP46. These findings established an elaborate mechanism of histone monoubiquitination in the fine-turning of ABA signaling and drought response via balancing H2Bub1 deposition and removal.
Project description:Transcription factors play a crucial regulatory role in plant drought stress responses. In this study, a novel drought stress related bZIP transcription factor, OsbZIP62, was identified in rice. This gene was selected from transcriptome analysis of several typical rice varieties with different drought tolerance. The expression of OsbZIP62 was obviously induced by drought, hydrogen peroxide, and abscisic acid (ABA) treatment. Overexpression of OsbZIP62-VP64 (OsbZIP62V) enhanced the drought tolerance and oxidative stress tolerance of transgenic rice, while the osbzip62 mutants showed the opposite phenotype. RNA-seq analysis showed that many stress-related genes (e.g. OsGL1, OsNAC10, and DSM2) were up-regulated in OsbZIP62V plants. OsbZIP62 could bind to the abscisic acid–responsive element (ABRE) and promoters of several putative target genes. Taken together, OsbZIP62 positively regulated rice drought tolerance through regulated the expression of genes associated with stress.
Project description:Jasmonates (JA) and abscisic acid (ABA) are phytohormones known to play important roles in plant response and adaptation to various abiotic stresses including salinity, drought, wounding, and cold. JAZ (JASMONATE ZIM-domain) proteins have been reported to play negative roles in JA signaling. However, direct evidence is still lacking that JAZ proteins regulate drought resistance. In this study, OsJAZ1 was investigated for its role in drought resistance in rice. Expression of OsJAZ1 was strongly responsive to JA treatment, and it was slightly responsive to ABA, salicylic acid, and abiotic stresses including drought, salinity, and cold. The OsJAZ1-overexpression rice plants were more sensitive to drought stress treatment than the wild-type rice Zhonghua 11 (ZH11) at both the seedling and reproductive stages, while the jaz1 T-DNA insertion mutant plants showed increased drought tolerance compared to the wild-type plants. The OsJAZ1-overexpression plants were hyposensitive to MeJA and ABA, whereas the jaz1 mutant plants were hypersensitive to MeJA and ABA. In addition, there were significant differences in shoot and root length between the OsJAZ1 transgenic and wild-type plants under the MeJA and ABA treatments. A subcellular localization assay indicated that OsJAZ1 was localized in both the nucleus and cytoplasm. Transcriptome profiling analysis by RNA-seq revealed that the expression levels of many genes in the ABA and JA signaling pathways exhibited significant differences between the OsJAZ1-overexpression plants and wild-type ZH11 under drought stress treatment. Quantitative real-time PCR confirmed the expression profiles of some of the differentially expressed genes, including OsNCED4, OsLEA3, RAB21, OsbHLH006, OsbHLH148, OsDREB1A, OsDREB1B, SNAC1, and OsCCD1. These results together suggest that OsJAZ1 plays a role in regulating the drought resistance of rice partially via the ABA and JA pathways.
Project description:Co-overexpression of the constitutively active form of OsbZIP46 and ABA-activated protein kinase SAPK6 improves drought and temperature stress resistance in rice
Project description:Plants have evolved to possess adaptation mechanism to cope with drought stress by reprograming transcriptional networks through drought responsive transcription factors, which in turn mediate morphological and physiological changes. NAM, ATAF1-2, and CUC2 (NAC) transcription factors are known to be associated with various developmental processes and stress tolerance. In this study, we functionally characterized the rice drought responsive NAC transcription factor OsNAC14. OsNAC14 was predominantly induced at meiosis stage, and induced by drought, high salinity, ABA and low temperature in leaves than roots. Overexpression of OsNAC14 resulted in drought tolerance at the vegetative growth stage and enhanced filling rate at vegetative growth. OsNAC14 overexpression elevated expression of genes related to DNA damage repair, defense response, strigolactone biosynthesis, which correlated with resistance to drought tolerance. Furthermore, OsNAC14 directly bound to the promoter of drought inducible OsRAD51A1, a key component in homologous recombination in DNA repair system. These results indicate that OsNAC14 mediate drought tolerance by recruiting factors involved in DNA damage repair and defense response to enable plant to protect from cellular damage caused by drought stress, thereby provide mechanism for drought tolerance.