Project description:Rice reproductive development is highly sensitive to high temperature stress. In rice flowering occurs over a period of at least 5 days. Heat stress alters the global gene expression dynamics in panicle especially during pollen development, anthesis and grain filling. Some of the rice genotypes like Nagina 22 show better spikelet fertility and grain filling compared to high yielding and popular rice cultivars like IR 64. We carried out microarray analysis of 8 days heat stressed panicles of Nagina22, heat and drought tolerant aus rice cultivar and IR64, a heat susceptible indica genotype along with unstressed samples of Nagina22 and IR64 so as to understand the transcriptome dynamics in these two genotypes under heat stress and to identify the genes important for governing heat stress tolerance in rice.
Project description:we utilized transcriptome sequencing to identify differentially expressed genes in rice heat-tolerant line and heat-sensitive line under high night temperature stress .
Project description:we utilized microRNA sequencing to identify differentially expressed miRNAs in rice heat-tolerant line and heat-sensitive line under high night temperature stress .
Project description:we utilized microRNA sequencing to identify differentially expressed miRNAs in rice heat-tolerant line and heat-sensitive line under high night temperature stress .
Project description:Heat stress along with other abiotic stresses is one of the major factors affecting crop health and overall yield in a tropical country like India. Thus, there is an urgent need to understand the dynamics of heat responsiveness at the molecular as well as physiological level. Fortunately, India has a number of indigenous varieties that show tolerance to extremes in temperature during the scorching summer months. The cultivar Annapurna is a fast growing dwarf variety of rice that is heat tolerant while the most widely grown indica rice in South and Southeast Asia, IR64, is susceptible to high temperatures. These two cultivars present an excellent opportunity to study the differences in response to heat stress, and, thereby help in elucidating the genes involved in conferring tolerance to high temperature. The present study involves transcript profiling of the two cultivars, Annapurna (tolerant) and IR64 (susceptible) under both control and heat stressed conditions.
Project description:To comprehend the gene expression profile in rice panicle under high temperature, Agilent 4×44k rice oligo microarray experiments were carried out using rice panicle of post-meiosis at 0 min, 10min, 20 min, 60 min, and 2 hr after the treatment of 40 degree centigrade, and the differentially expressed genes at the time course were involved in binding, catalysis, stress response, and cellular process. The significantly expressed genes were mainly up-regulated. Among HR genes, the predominant transcription factor gene families were Hsf, NAC, AP2/ERF, WRKY, MYB, and C2H2. The MapMan analysis demonstrated that, under heat treatment, the HR genes were enriched in the pathways related to biotic stress, abiotic stress including heat and cold, and cell cycle and development, ubiquitin-proteasome , lipid and secondary metabolisms, which revealed the great importance of cross-talk and protein homeostasis in response to heat in rice panicle of post-meiosis.
Project description:Purpose: understanding the complex genetic control of heat tolerance can be reached using whole transcriptome sequencing (RNA-seq) that is currently the most powerful tool to identify genes differentially regulated. Heat responses differ greatly between sensitive and tolerant genotypes, mainly in terms of the amount of genes and pathways involved in the response and differences in the expression level of constitutive genes in many pathways. The present study aims to compare the molecular response of Brazilian flooded rice cultivars with variable sensitivity to heat stress at anthesis stage and to discuss the possible processes involved in heat tolerance. Methods: Panicle mRNA profiles of cultivars IRGA 428 (sensitive) and BR-IRGA 409 (tolerant) were generated by deep sequencing, in triplicate (each replicate is composed of two plants), under three days of heat stress and control condition at anthesis stage, using Illumina Hiseq 2500. The sequence reads from each sample that passed quality filters were mapped independently, generating contigs that were aligned with the reference genome sequences in rice (cv. MH63-indica). The transcripts were analyzed at the expression level with statistic test (EdgeR – Rstudio) to identify the significant changes in the expression level of the genes for each treatment condition and cultivar follow by identification of metabolic pathways (MapMan and Cytoscape) based on different programs. Results: Using an optimized data analysis workflow, we identified 16,871 transcripts in the rice spikelet of sensitive and tolerant cultivars with HISAT workflow. Using filtered and aligned reads, transcript levels were used to find differentially expressed genes (DEGs) at different thermal condition and cultivars. We identified 2,064 genes for BR-IRGA 409 and 1,078 genes for IRGA 428 that showed a significant change in expression in response to heat stress (LogFC ≥0.5 and adjusted p-value <0.001). When it was examined the multi-factor responsive genes, that is genes with an interaction between cultivar and heat stress (multi-factor analysis - cultivars vs control and high temperature), it was identified 65 DEGs in response to heat stress (LogFC ≥0.5 and adjusted p-value <0.001). Comparison of our data set with other RNA-seq studies shows a significant overlap in heat responsive genes (hypergeometric enrichment test). This core set of genes common among RNA-seq studies indicates that it may be associated with basal response to heat. In the present study, genes related to light reaction pathway were induced in the panicle of the cultivar IRGA 428, while these genes in cultivar BR-IRGA 409 were already expressed highly in control conditions. The basal level of these genes in BR-IRGA 409 was as high as the heat-induced level in the sensitive IRGA 428. Photosynthesis is known to occur in rice panicles, but little has been reported about the photosynthetic characteristics of such panicles. To cope with heat stress, plants have developed a sophisticated mechanism to repair photosystem damage. Therefore, in IRGA 428 the induction of these genes suggests the activation of a repair mechanism to reverse damage on the photosynthetic apparatus caused by the heat stress. The difference in basal levels of the photosynthetic genes may be a contributing factor to the differences in spikelet fertility between the cultivars under heat stress. Conclusion: This is the first study to evaluate the heat tolerance of Brazilian rice cultivars. In panicle tissue, most canonical heat responsive genes, such as HSF family, small HSP family and FKBP family, show a similar response in both Brazilian cultivars, despite the fact that these cultivars have not been specifically selected for heat tolerance. The response of photosynthetic genes to heat stress is a major difference between the cultivars BR-IRGA 409 and IRGA 428. This study indicates that the higher basal expression of photosynthetic genes in the panicle provides improved spikelet fertility under heat stress. This may provide potential markers that can be used to identify heat tolerant genotypes among rice breeding programs. This study emphasizes that the characterization of heat stress responses in individual cultivars provides insights into both the basic mechanisms of heat response and assists with understanding the complex phenomenon of responses to high temperature stress.
Project description:We analyzed the transcriptome profiles for rice grain from heat-tolerant and -sensitive lines in response to high night temperatures at the early milky stage using the Illumina Sequencing method. On the 8th day after the labeled florets flowered, plants with the same label were transferred to chambers and maintained at a temperature of 38.0â±â0.5°C (treatment) or 25.0â±â0.5°C (control) for the dark period (10 h), and 26.0â±â0.5°C (both treatment and control) for the light period (14 h). Three biological replicates of the temperature treatments were grown under the same conditions. After 48 h of treatment, samples containing 45 grains with labels from the same region (middle to bottom part) of labelled ears were harvested, packed in aluminum foil, and flash-frozen in liquid nitrogen until further use. A total of 12 rice grain samples were harvested, i.e., controls (TC1, TC2 and TC3) and treatments (TT1, TT2 and TT3) of the three biological replicates of the heat-tolerant line, and controls (SC1, SC2 and SC3) and treatments (ST1, ST2 and ST3) of the three biological replicates of the heat-sensitive line.
Project description:To comprehend the profile of rice gene expression at reproductive stage under high temperature, Agilent 4×44k rice oligo microarray experiments were carried out using rice panicle of developmental stage 7-9 at 0min, 20min, 1hr, 2hr, 4hr, and 8hr after the treatment of 40 degree centigrade, and the significantly expressed genes mainly involved in transcriptional regulation, transport, cellular homeostasis, and stress response were identified. Among them, the predominant transcription factor gene families were Hsf, NAC, AP2/ERF, WRKY, MYB, and C2H2. KMC analysis discovered the time-dependent gene expression pattern under heat. The results of motif co-occurrence on the promoters of genes from an early up-regulated cluster showed the important roles of GCC box, HSE, ABRE, and CE3, and unraveled the possible cross-talk mechanism during heating. The response model central to ROS combined with transcriptome data indicated the great importance to maintain ROS balance in heat response in rice panicle and the wide existing of cross-talks.
Project description:To comprehend the profile of rice gene expression at reproductive stage under high temperature, Agilent 4M-CM-^W44k rice oligo microarray experiments were carried out using rice panicle of developmental stage 7-9 at 0min, 20min, 1hr, 2hr, 4hr, and 8hr after the treatment of 40 degree centigrade, and the significantly expressed genes mainly involved in transcriptional regulation, transport, cellular homeostasis, and stress response were identified. Among them, the predominant transcription factor gene families were Hsf, NAC, AP2/ERF, WRKY, MYB, and C2H2. KMC analysis discovered the time-dependent gene expression pattern under heat. The results of motif co-occurrence on the promoters of genes from an early up-regulated cluster showed the important roles of GCC box, HSE, ABRE, and CE3, and unraveled the possible cross-talk mechanism during heating. The response model central to ROS combined with transcriptome data indicated the great importance to maintain ROS balance in heat response in rice panicle and the wide existing of cross-talks. Heat shock induced gene expression in rice panicle of developmental stage 7-9 was measured at 0min, 20min, 1hr, 2hr, 4hr, and 8hr after the treatment of 40 degree centigrade in plant growth chamber. Two independent replicate experiments were performed at each time point.