QTL Mapping and Identification of Candidate Genes for Heat Tolerance at the Flowering Stage in Rice

Abstract

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Background:</jats:bold> High-temperature stress can cause serious abiotic damage that limits the yield and quality of rice. Heat tolerance during the flowering stage of rice is a key trait that can guarantee a high and stable yield under heat stress. Heat tolerance is a complex trait that is regulated by numerous quantitative trait loci (QTLs); of which, however, few underlying genes have been fine mapped and cloned.<jats:bold>Results:</jats:bold> In this study, the F<jats:sub>2:3</jats:sub> population derived from a cross between Huanghuazhan (HHZ), a heat-tolerant <jats:italic>indica</jats:italic> cultivar, and 9311, a heat-sensitive <jats:italic>indica </jats:italic>rice variety, were used to map the QTLs for heat tolerance during the flowering stage of rice. The F<jats:sub>2:3</jats:sub> lines were treated under 38 °C from 9:30 am to 3:30 pm continuously for 3 days in a phytotron, and spikelet fertility was assessed. A new major QTL, <jats:italic>qHTT8</jats:italic>, controlling heat tolerance was located on chromosome 8 using the bulked-segregant analysis (BSA)-seq method. The QTL <jats:italic>qHTT8</jats:italic> was determined to be located in the 355500–4520000 bp region, with a size of 0.965 Mb. The candidate region of <jats:italic>qHTT8</jats:italic> on chromosome 8 contained 65 predicted genes. Ten putative predicted genes were found to be associated with abiotic stress tolerance. In future studies, the backcross population will be constructed to fine map and validate the effect of <jats:italic>qHTT8</jats:italic>.<jats:bold>Conclusion:</jats:bold> The information obtained in this study is useful for the fine mapping and cloning of <jats:italic>qHTT8</jats:italic> and breeding heat-tolerant varieties of rice using marker-assisted selection.</jats:p>