Project description:In this study, genome-wide transcriptome profiling was used to understand molecular genetic mechanism of drought tolerance in rice. Illumina High-Seq 2000 platform was used for sequencing RNA from leaf tissue of rice plants exposed to controlled drought stress and well-watered conditions. The differentially expressed genes were used to identify biological process and cis-regulatory elements enriched under drought stress compared to well-watered conditions.
Project description:A heat and drought tolerant rice cultivar (N22) was grown in the field under control and drought conditions during the dry season in 2013. Drought was applied during early grain filling and resulted in simultaneous heat stress, leading to reduced grain yield and quality. Total RNA was extracted from developing seeds under stress and control (fully flooded) conditions and RNA-seq analysis was performed. These samples are a part of a bigger experiment analysing the responses of three contrasting rice cultivars (N22, Dular, Anjali) to combined heat and drought stress including different organs (developing seeds, flag leaves, flowering spikelets) and developmental stages (early grain filling, flowering) at the transcriptomic level.
Project description:The current knowledge of drought stress transcriptomes in rice are mostly relying on comparative studies of diverse genetic background under drought. A more reliable approach is to use near-isogenic lines (NILs) with a common genetic background (Donar parent: Aday Sel, Recurrent parent: IR64), but contrasting levels of resistance to drought stress under initial exposure to water deficit. Here, we examined two pairs of NILs in IR64 background with contrasting drought tolerance. We obtained gene expression profile in roots of rice NILs under different levels of drought stress help to identify genes and mechanisms involved in drought stress.
Project description:The current knowledge of drought stress transcriptomes in rice are mostly relying on comparative studies of diverse genetic background under drought. A more reliable approach is to use near-isogenic lines (NILs) with a common genetic background (Donar parent: Aday Sel, Recurrent parent: IR64), but contrasting levels of resistance to drought stress under initial exposure to water deficit. Here, we examined two pairs of NILs in IR64 background with contrasting drought tolerance. We obtained gene expression profile in panicles of rice NILs under different levels of drought stress help to identify genes and mechanisms involved in drought stress.
Project description:The current knowledge of drought stress transcriptomes in rice are mostly relying on comparative studies of diverse genetic background under drought. A more reliable approach is to use near-isogenic lines (NILs) with a common genetic background (Donar parent: Aday Sel, Recurrent parent: IR64), but contrasting levels of resistance to drought stress under initial exposure to water deficit. Here, we examined two pairs of NILs in IR64 background with contrasting drought tolerance. We obtained gene expression profile in shoots of rice NILs under different levels of drought stress help to identify genes and mechanisms involved in drought stress.
Project description:Plant stress response and tolerance mechanisms are controlled by diverse genes. Transcription factors have been implicated in drought tolerance under drought stress conditions. Identification of target genes of such transcription factors could offer molecular regulatory networks by which the tolerance mechanisms orchestrated. Previously, we generated transgenic rice plants with 4 rice transcription factors OsNAC5, 6, 9, and 10 under the root-specific promoter RCc3 that were tolerant to drought stress with less loss of grain yield under drought conditions. To understand the molecular mechanisms of drought tolerance, we performed ChIP-Seq and RNA-Seq analyses to identify direct target genes of the OsNACs using the RCc3:MYC-OsNACs roots. A total of 475 binding loci of 4 OsNACs were identified by cross-referencing the binding occupancy of OsNACs at promoter regions and expression levels of corresponding genes. The binding loci are distributed on promoter regions of 391 target genes that were directly up-regulated by OsNACs in four RCc3:MYC-OsNAC transgenic roots. The direct target genes were related to transmembrane/transporter activity, vesicle, plant hormone, carbohydrate metabolism, and transcription factors. The direct targets of each OsNAC are in a range of 4.0 to 8.7% of the genes up-regulated in RNA-Seq data sets. Thus, each OsNAC up-regulates of corresponding direct target genes that alters root system architectures of RCc3:OsNACs for drought tolerance. Our results provide valuable resources for functional dissection of the molecular mechanisms for plant drought tolerance.
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:Rice (Oryza sativa), the major staple food crop is being cultivated under varying ecosystems ranging from irrigated lowland to rainfed upland environments. Improvement in the rice production under drought prone unfavourable environment depends on the development of drought tolerant genotypes which needs thorough understanding of physiological and molecular events behind the tolerance mechanism. There is considerable genetic variation for drought tolerance mechanism within the cultivated gene pool. To understand the diversity of drought response, two indica rice genotypes namely, i) Apo, an up-land drought tolerant indica veriety from Philippines and ii) IR64, a popular high yielding drought susceptible genotype were selected for this study. We used the 22K rice Oligoarray from Agilent technologies to study the transcript profile in the leaves of the two contrasting rice genotypes under control and drought stressed conditions during vegetative phase. Keywords: Drought response We used Agilent rice gene chips (G4138A) to investigate the transcript level changes in rice leaf tissues during drought stress. We used two contrasting rice genotypes (IR64 drought susceptible and Apo drought tolerant) differing in their degree of drought tolerance. Plants were grown under green house conditions and drought stress was imposed on 33rd DAS. Leaf sampling was done in both control and drought stressed plants after 6 days of drought stress. Three replications of microarray experiments were carried out by hybridizing the control samples against the drought stressed samples.
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.