Project description:We initiated the project to identify new QTL regulating the salt tolerance in rice. We carried out linkage mapping using 148 recombinant inbred lines derived from IR29 and Pokkali. The extracted genomic DNA was subjected to genotyping with single-nucleotide polymorphism (SNP) markers using an Affymetrix Axiom Rice 56k SNP Genotyping Array.The manuscript related to the project is "Identification of new QTL for salt tolerance from rice variety Pokkali".
Project description:Analysis of root gene expression of salt-tolerant genotypes FL478, Pokkali and IR63731, and salt-sensitive genotype IR29 under control and salinity-stressed conditions during vegetative growth. Results provide insight into the genetic basis of salt tolerance in indica rice. Keywords: stress response
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:Climate change is affecting crop production due to soil salinization and water scarcity, and is predicted to worsen in the coming years. Rice is a major staple food and the most salt-sensitive cereal. High salinity in the soil triggers several adaptive responses in rice to cope with osmotic and ionic stress at the physiological, cellular and molecular levels. A major QTL for salinity tolerance, named Saltol, is present on chromosome 1 of Indian rice landrace varieties such as Pokkali and Nona Bokra. In this study, we characterized the physiological and early proteomic responses to salinity in FL478, an inbred rice line harboring the Saltol region. For this, plantlets were cultured in hydroponic cultures with 100 mM NaCl and evaluated at 6, 24 and 48h. At the physiological level, salinity significantly reduced shoot length after 48 h, whereas root length significantly increased. Moreover, the Na+/K+ ratio was maintained at lower levels in the shoots compared to the roots FL478 plantlets. On the other hand, roots showed a faster and more coordinated proteomic response than shoots, which was evident from only 6h of treatment. These responses were markedly related with transcription- and translation-related proteins. Moreover, roots exhibited a higher accumulation of stress-related proteins in response to salinity treatment, like peroxidase and SalT, which are both present in the Saltol QTL. Both, physiological and proteomic response, showed that roots respond in a highly adaptive manner to salinity stress compared to shoots, which suggests that this tissue is critical to the tolerance observed in varieties harbouring the Saltol region.
Project description:We report the application of small RNA sequencing (Illumina) technology for the identification of miRNA from root and leaf tissues of pokkali rice cultivar grown under normal and salt stress conditions. We used this data to predict and identify known and novel miRNAs.
Project description:A submergence tolerant indica rice cultivar FR13A, was also reported to withstand salt stress and proven in our experiments. The mechanism of tolerance is yet to be studied by forward genetics approach. However, it is known that salt stress tolerance is governed by several QTLs and not by a single gene. To understand the mechanism of such a complex mechanism of salt tolerance we selected, two indica rice genotypes namely, I) FR13A, a tolerant indica variety and ii) IR24, a susceptible genotype 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 constitutive and salt stress conditions at seedling stage. Keywords: Mechanism of salt tolerance
Project description:Analysis of root gene expression of salt-tolerant genotypes FL478, Pokkali and IR63731, and salt-sensitive genotype IR29 under control and salinity-stressed conditions during vegetative growth. Results provide insight into the genetic basis of salt tolerance in indica rice. Experiment Overall Design: Seedlings were cultured in sand and irrigated with a nutrient solution for 22 d (salt-treated) and 30 d (control) after germination, respectively. Salinity treatment was applied by adding NaCl and CaCl2 (5:1 molar concentration) in two steps over a period of 3 days (final electrical conductivity: 7.4 dS m-1) to prevent osmotic shock. All plants were harvested on day 30.
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:Over the years, many traditional rice varietites of India were sourced and studied owing to their ability to withstand abiotic pressures like excessive salinity in the soil and water. These cultivars growing in specific areas of the country represent a rich gene pool from where a deeper understanding of the processes underlying tolerance to abiotic stress can be gained. Indigenous varieties like Nonabokra and Pokkali are known salt tolerant varieties and are being studied in great detail. In the present study, we have analyzed the transcriptomes of the contrasting cultivars; Nonabokra (tolerant), Pokkali (tolerant) and IR29 (susceptible) in order to decipher the differences in their responses to salinity stress by utilizing microarray.
Project description:An indica rice cultivar FR13A, is widely grown as submergence tolerant variety and can withstand submergence up to two weeks. The tolerance is governed by a major QTL on chromosome 9 and represented as sub1. Recently the gene for sub1 has been mapped and cloned. However, the trait is governed by several QTLs and not by a single gene. To understand the mechanism of submergence tolerance we selected, two indica rice genotypes namely, I) FR13A, a tolerant indica variety and ii) IR24, a susceptible genotype 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 constitutive and submerged conditions at seedling stage. Keywords: Mechanism of submergence tolerance