Project description:Chilling stress is a major abiotic stress that affects rice growth and development. Rice seedlings are quite sensitive to chilling stress and this harms global rice production. Comprehensive studies of the molecular mechanisms for response to low temperature are of fundamental importance to chilling tolerance improvement. The number of identified cold regulated genes (CORs) in rice is still very small. Circadian clock is an endogenous timer that enables plants to cope with forever changing surroundings including light–dark cycles imposed by the rotation of the planet. Previous studies have demonstrated that the circadian clock regulates stress tolerances in plants show circadian clock regulation of plant stress tolerances. However, little is known about coordination of the circadian clock in rice chilling tolerance. In this study, we investigated rice responses to chilling stress under conditions with natural light-dark cycles. We demonstrated that chilling stress occurring at nighttime significantly decreased chlorophyll content and photosynthesis efficiency in comparison with that occurring at daytime. Transcriptome analysis characterized novel CORs in indica rice, and suggested that circadian clock obviously interferes with cold effects on key genes in chlorophyll (Chl) biosynthesis pathway and photosynthesis-antenna proteins. Expression profiling revealed that chilling stress during different Zeitberger times (ZTs) at nighttime repressed the expression of those genes involved Chl biosynthesis and photosynthesis, whereas stress during ZTs at daytime increases their expression dramatically. Moreover, marker genes OsDREBs for chilling tolerance were regulated differentially by the chilling stress occurring at different ZTs. The phase and amplitude of oscillation curves of core clock component genes such as OsLHY and OsPRR1 are regulated by chilling stress, suggesting the role of chilling stress as an input signal to the rice circadian clock. Our work revealed impacts of circadian clock on chilling responses in rice, and proved that the effects on the fitness costs are varying with the time in a day when the chilling stress occurs.
Project description:The aim of this study was to conduct global gene expression profiling and comparative analysis of two chilling tolerant rice varieties, Jumli Marshi and Sijung (spp. Japonica), during early chilling stress (24h, 10C). Leaf tissue from cv. Jumli Marshi and cv. Sijung plants grown under chilling stress conditions were harvested after 4 and 24 h. Control plants (0 h) were harvested at the beginning of the experiment, i.e., at mid-day. Three biological replicates were profiled for each time point and variety. In order to readily detect highly (saturated) as well as weakly (near background signal) expressed genes, scanning was done twice on the microarrays: at the PMT sensitivity level 100% (pmt100) and 10% (pmt10).
Project description:In this study, we used a cross-species network approach to uncover nitrogen (N)-regulated network modules conserved across a model and a crop species. By translating gene network knowledge from the data-rich model Arabidopsis (Arabidopsis thaliana, ecotype Columbia-0) to a crop, rice (Oryza sativa spp. japonica (Nipponbare)), we identified evolutionarily conserved N-regulatory modules as targets for translational studies to improve N use efficiency in transgenic plants.
Project description:Improvement of chilling tolerance is a key strategy to face potential menace from abnormal temperature in rice production, which depends on the signaling network triggered by receptors. However, little is known about the QTL genes encoding membrane complexes for sensing cold. Here, Chilling-tolerance in Gengdao/japonica rice 1 (COG1) was isolated from a chromosome segment substitution line containing a QTL (qCS11-jap) for chilling sensitivity. The major gene COG1 was found to confer chilling tolerance in japonica rice. In natural rice populations, only the haplogroup1 encoded a functional COG1. Evolutionary analysis showed that COG1 originated from Chinese O. Rufipogon and was fixed in japonica rice during domestication. COG1, a membrane-localized LRR-RLP, targeted and activated the kinase OsSERL2 in a cold-induced manner, promoting chilling tolerance. Furthermore, the cold signal transmitted by COG1-OsSERL2 activates OsMAPK3 in the cytoplasm. Our findings reveal a cold-sensing complex, which mediates signaling network for the chilling defense in rice.
Project description:Changes in patterns of gene expression are believed to be responsible for the phenotypic differences within and between species. Although the evolutionary significance of functional mutations has been emphasized in rice domestication, little is known about the differences in gene regulation underlying the phenotypic diversification among rice varieties. MicroRNAs (miRNAs) are small regulatory RNAs that play crucial roles in regulating post-transcriptional gene expression. Here, we studied the variation in the expression of both miRNAs and mRNA transcripts in three indica and three japonica rice varieties using RNA sequencing (RNA-seq) to examine the miRNA regulatory effect on target gene expression in rice. In total, 71.0%, 9.2%, and 1.5% of the expressed mature miRNAs showed tissue, subspecies, and tissue-subspecies interaction-biased expression. Most of these differentially expressed miRNAs are evolutionarily weakly conserved. To examine the miRNA regulatory effect on global gene expression under endogenous conditions, we performed pair-wise correlation coefficient analyses on the expression levels of 240 mature miRNAs and 1178 messenger RNAs (mRNAs) both globally and for each specific miRNA-mRNA pair. We found that the deeply conserved miRNAs can significantly decrease the target mRNA abundance. In addition, a total of 109 miRNA-mRNA pairs were identified as significantly correlated pairs (Adjusted p<0.01). Of those, 41 pairs showed positive correlations, while 68 pairs showed negative correlations. Functional analysis elucidated that these mRNAs belonged to different biological pathways that could regulate the stress response, metabolic processes, and rice development. In conclusion, the joint interrogation of miRNA and mRNA expression profiles in this study proved useful for the study of the role of miRNA expression and regulation in the plant transcriptome.
Project description:Plants respond to low temperature through an intricately coordinated transcriptional network controlled by specific groups of transcription factors. Major regulatory pathways in plants that evolved to withstand freezing by cold acclimation have been elucidated in Arabidopsis. A prominent pathway is the CBF/DREB regulon, which was also shown to be evolutionarily conserved between temperate and warm-season plants. This study exploited the wide contrast in chilling tolerance between indica and japonica rice as model to dissect the hierarchical organization of early response regulatory networks by integrative analysis of promoter architecture and gene expression profiles. Analysis of the transcriptome of japonica rice identified a group of genes that were upregulated during the initial 24 hours at 10oC. Included among the 120 ‘early response’ genes were two transcription factors (ROS-bZIP1, OsMyb4) and another larger sub-group with a common denominator of having the as1/ocs element in their promoters. ROS-bZIP1, OsMyb4 and the as1/ocs element-containing genes were also induced by exogenous H2O2 at ambient temperature, thus are likely components of a regulatory module (ROS-bZIP1-as1/ocs regulatory module) that is activated by elevated intracellular ROS induced by cold stress. Comparative analysis of the expression of ROS-bZIP1-as1/ocs regulatory module between tolerant (CT6748-8-CA-17) and intolerant (INIAP12) rice cultivars showed positive correlation of the activity of the regulon with genotypic differences in chilling tolerance. A hypothetical model of an ROS-mediate gene regulon was developed. Based on this model, it was hypothesized that the putative ROSbZIP1-as1/ocs regulatory module has a prominent role in configuring early or rapid responses to chilling in rice seedlings and that such pathway is independent of the CBF/DREB-mediated and ABA-mediated regulons. Background Keywords: Response to temperature at different time points
Project description:To understand the dynamics and global gene reprogramming in the early response to mechanical wounding in rice, the transcriptional response to mechanical injury was analyzed. A time-course experiment revealed the highly dynamic nature of the wound response in rice. Mechanical wounding triggered extensive gene expression reprogramming in the locally wounded leaf, affecting various physiological processes, including defense mechanisms and potentially tissue repair and regeneration. The rice response to mechanical wounding displayed both differences and similarities compared to the response to jasmonate treatment. These results highlight the importance of early JA signaling in response to mechanical stress in rice. This analysis provides an overview of the global transcriptional response to mechanical stress in rice, offering valuable insights for future studies on rice's response to injury, insect attack, and abiotic stresses.
Project description:In order to identify new miRNAs, NAT-siRNAs and possibly abiotic-stress regulated small RNAs in rice, three small RNA libraries were constructed from control rice seedlings and seedlings exposed to drought or salt stress, and then subjected to pyrosequencing.
Project description:Rice is sensitive to chilling stress, especially at the seedling stage. To elucidate the molecular genetic mechanisms of chilling tolerance in rice, comprehensive gene expressions of two rice genotypes (chilling-tolerant LTH and chilling-sensitive IR29) with contrasting responses to chilling stress were comparatively analyzed. Results revealed distinct global transcription reprogramming between the two rice genotypes under time-series chilling stress and subsequent recovery conditions. A set of genes with higher basal expression were identified in LTH, indicating their possible role in intrinsic tolerance to chilling stress. Under chilling stress, the major effect on gene expression was up-regulation in LTH and strong repression in IR29. Early responses to chilling stress in both genotypes featured commonly up-regulated genes related to transcription regulation and signal transduction, while functional categories for late phase chilling regulated genes were diverse with a wide range of functional adaptations to continuous stress. Following the cessation of chilling treatments, there was quick and efficient reversion of gene expression in LTH, while IR29 displayed considerably slower recovering capacity at the transcriptional level. In addition, the detection of differentially-regulated TF genes and enriched cis-elements demonstrated that multiple regulatory pathways, including CBF and MYBS3 regulons, were involved in chilling stress tolerance. In present study, comprehensive gene expression using an Affymetrix rice genome array revealed a diverse global transcription reprogramming between two rice genotypes under chilling stress and subsequent recovery conditions. The dominant change in gene expression at low temperature was up-regulation in the chilling-tolerant genotype and down-regulation in the chilling-sensitive genotype. Early responses to chilling stress common to both genotypes featured up-regulated genes related to transcription regulation and signal transduction, while functional categories of LR-chilling regulated genes were clearly diverse with a wide range of functional adaptations. At the end of the chilling treatments, there was quick and efficient reversion of gene expression in LTH, while IR29 displayed considerably slower recovery capacity at the transcriptional level. Finally, analysis of differentially-regulated TF genes and enriched cis-elements demonstrated that multiple regulatory pathways, including CBF and MYBS3 regulons, are involved in chilling stress tolerance.
Project description:Rice is sensitive to chilling stress, especially at the seedling stage. To elucidate the molecular genetic mechanisms of chilling tolerance in rice, comprehensive gene expressions of two rice genotypes (chilling-tolerant LTH and chilling-sensitive IR29) with contrasting responses to chilling stress were comparatively analyzed. Results revealed distinct global transcription reprogramming between the two rice genotypes under time-series chilling stress and subsequent recovery conditions. A set of genes with higher basal expression were identified in LTH, indicating their possible role in intrinsic tolerance to chilling stress. Under chilling stress, the major effect on gene expression was up-regulation in LTH and strong repression in IR29. Early responses to chilling stress in both genotypes featured commonly up-regulated genes related to transcription regulation and signal transduction, while functional categories for late phase chilling regulated genes were diverse with a wide range of functional adaptations to continuous stress. Following the cessation of chilling treatments, there was quick and efficient reversion of gene expression in LTH, while IR29 displayed considerably slower recovering capacity at the transcriptional level. In addition, the detection of differentially-regulated TF genes and enriched cis-elements demonstrated that multiple regulatory pathways, including CBF and MYBS3 regulons, were involved in chilling stress tolerance. In present study, comprehensive gene expression using an Affymetrix rice genome array revealed a diverse global transcription reprogramming between two rice genotypes under chilling stress and subsequent recovery conditions. The dominant change in gene expression at low temperature was up-regulation in the chilling-tolerant genotype and down-regulation in the chilling-sensitive genotype. Early responses to chilling stress common to both genotypes featured up-regulated genes related to transcription regulation and signal transduction, while functional categories of LR-chilling regulated genes were clearly diverse with a wide range of functional adaptations. At the end of the chilling treatments, there was quick and efficient reversion of gene expression in LTH, while IR29 displayed considerably slower recovery capacity at the transcriptional level. Finally, analysis of differentially-regulated TF genes and enriched cis-elements demonstrated that multiple regulatory pathways, including CBF and MYBS3 regulons, are involved in chilling stress tolerance. In this study, parallel transcriptomic analysis in two rice genotypes with contrasting chilling-tolerant phenotypes was performed to identify and characterize novel genes involved in chilling stress tolerance in rice.