Project description:Integrating Linkage Mapping and Comparative Transcriptome Analysis for Discovering Candidate Gene Associated with Salt Tolerance in Rice of RNA
Project description:Dongxiang wild rice (Oryza rufipogon Griff.) is the progenitor of cultivated rice (Oryza sativa L.) and is well known for its superior level of tolerance against cold, drought and diseases. To date, however, little is known about the salt-tolerant character of Dongxiang wild rice. To elucidate the molecular genetic mechanisms of salt-stress tolerance in Dongxiang wild rice, the Illumina HiSeq 2000 platform was used to analyze the transcriptome profiles of the leaves and roots at the seedling stage under salt stress compared with those under normal conditions. The analysis results for the sequencing data showed that 6,867 transcripts were differentially expressed in the leaves (2,216 up-regulated and 4,651 down-regulated) and 4,988 transcripts in the roots (3,105 up-regulated and 1,883 down-regulated). Among these differentially expressed genes, the detection of many transcription factor genes demonstrated that multiple regulatory pathways were involved in salt stress tolerance. In addition, the differentially expressed genes were compared with the previous RNA-Seq analysis of salt-stress responses in cultivated rice Nipponbare, indicating the possible specific molecular mechanisms of salt-stress responses for Dongxiang wild rice. A large number of the salt-inducible genes identified in this study were co-localized onto fine-mapped salt-tolerance-related quantitative trait loci, providing candidates for gene cloning and elucidation of molecular mechanisms responsible for salt-stress tolerance in rice.
Project description:Dongxiang wild rice (Oryza rufipogon Griff.) is the progenitor of cultivated rice (Oryza sativa L.) and is well known for its superior level of tolerance against cold, drought and diseases. To date, however, little is known about the salt-tolerant character of Dongxiang wild rice. To elucidate the molecular genetic mechanisms of salt-stress tolerance in Dongxiang wild rice, the Illumina HiSeq 2000 platform was used to analyze the transcriptome profiles of the leaves and roots at the seedling stage under salt stress compared with those under normal conditions. The analysis results for the sequencing data showed that 6,867 transcripts were differentially expressed in the leaves (2,216 up-regulated and 4,651 down-regulated) and 4,988 transcripts in the roots (3,105 up-regulated and 1,883 down-regulated). Among these differentially expressed genes, the detection of many transcription factor genes demonstrated that multiple regulatory pathways were involved in salt stress tolerance. In addition, the differentially expressed genes were compared with the previous RNA-Seq analysis of salt-stress responses in cultivated rice Nipponbare, indicating the possible specific molecular mechanisms of salt-stress responses for Dongxiang wild rice. A large number of the salt-inducible genes identified in this study were co-localized onto fine-mapped salt-tolerance-related quantitative trait loci, providing candidates for gene cloning and elucidation of molecular mechanisms responsible for salt-stress tolerance in rice. Leaf and root mRNA profiles of Dongxiang wild rice at the seedling stage with or without salt stress were generated by deep sequencing, on Illumina Hiseq 2000 platform.
Project description:The advent of next generation sequencing (NGS) has greatly enriched the database of miRNAs. For plants so far 8455 miRNAs sequences from 73 species and 15401 miRNAs sequences from 150 species have been deposited in miRBase 21.0 and Plant Non-coding RNA Database, respectively. The occurrence of miRNAs in such a huge number, which is still increasing, is because of the fact that the profile of miRNAs expression differs greatly from species to species, both quantitatively and qualitatively. Besides, even within a species it is expected that the miRNA expression profile would differ from cultivar to cultivar depending on the trait with regard to which the two cultivars differ, and on the same logic it is also expected that their expression profile would differ considerably in the plant under contrasting environmental conditions. However, report on comparative study of expression profile of miRNAs in rice cultivars, or in any crop cultivars, contrast for salt tolerance, or tolerance to any abiotic stress is scant. Therefore, the current study was planned to see the expression profile of miRNAs in a salt-tolerant rice (Oryza sativa L. ssp indica) cultivar (cv.) Pokkali in presence and absence of NaCl and to check the response pattern of a few important salt-responsive miRNAs in a salt-sensitive rice cultivar Badami in order to identify the miRNAs and their targets that could be involved in the salt tolerance process
Project description:Rice is the most salt sensitive cereal crop and its cultivation is particularly threatened by salt stress. This study reports the development of salt tolerant introgressed lines (ILs) derived from crosses between the salt tolerant indica rice variety FL478, which harbors the Saltol QTL, and the salt-sensitive japonica elite cultivar PL12. Although the introgression of the Saltol QTL has been widely used to improve salinity tolerance, the molecular basis underlying the salinity tolerance conferred by Saltol remains poorly understood. Equally, the impact of introgressions from a Saltol donor parent on the global transcriptome of ILs is largely unknown. Here, genotyping-by-sequencing (GBS) and Kompetitive allele specific PCR (KASP) genotyping, in combination with step-wise phenotypic selection in hydroponic culture, were used for the identification of salt-tolerant ILs. Transcriptome-based genotyping allowed the fine mapping of indica genetic introgressions in the best performing IL line (IL22). A total of 1,595 genes were identified in indica regions in IL22, which mainly located in large introgressions at Chromosomes 1 and 3. In addition to OsHKT1;5, an important number of genes potentially contributing to salt stress tolerance were identified in indica segments of IL22. Comparative transcript profiling also revealed important transcriptional reprograming in IL22 plants both under non-stress and salt-stress conditions, indicating an impact on the transcriptome of the japonica background by the indica introgressed genes and vice versa. Interactions among indica and japonica genes would provide novel regulatory networks contributing to salt stress tolerance in introgression rice lines.
Project description:Salinity is a major constraint on agricultural productivity worldwide. Despite the serious impacts of salinity on rice yields, particularly in Asia, mechanisms of salt tolerance in wild rice species are yet to be explored. Here we extracted and quantified root microsomal proteins of Oryza australiensis accessions contrasting in salt tolerance. Whole root systems of two-week-old seedlings were treated with 80 mM NaCl for 30 days or left untreated. Proteins were quantified by tandem mass tags (TMT) and triple-stage MS. We found >200 differentially expressed proteins (DEPs) between the salt-treated and control in the two accessions (p-value <0.05). Gene Ontology (GO) analysis showed that ‘metabolic process’, ‘transport’ and ‘transmembrane transporter’ activities were highly responsive categories following salt treatment of the O. australiensis seedlings. In particular, ATPases and SNARE proteins were up-regulated in the salt-tolerant accession and appeared to have a major role in response to salinity. ATPases are the central link between energy generation and transport, while SNARE proteins facilitate vesicle fusion and interact with voltage-gated potassium channels to regulate K+ influx. We successfully validated the putative function of two strongly upregulated proteins, a monosaccharide transporter and a VAMP-like protein, by measuring the growth under salinity of yeast mutants in which homologous genes were deleted. Our results demonstrate the potential use of wild species as a source of new mechanisms of salt tolerance for the breeding of elite cultivars of rice.