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: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.

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.

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Oryza sativa

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