Fine mapping of <i>qSKC-1</i>, a major quantitative trait locus for shoot K<sup>+</sup> concentration, in rice seedlings grown under salt stress

Abstract

Shoot K⁺ concentration (SKC) is an important physiological parameter used to evaluate salt tolerance at the seedling stage in rice (<i>Oryza sativa</i> L.). <i>qSKC-1</i>, a major quantitative trait locus for SKC in rice under salt stress, was detected on chromosome 1 using three F₂ populations constructed by crossing 'Nipponbare' and its two salt-sensitive mutants (<i>rss2</i> and <i>rss4</i>) with an <i>indica</i> cultivar 'Zhaiyeqing8' ('ZYQ8'). In this study, the chromosomal location of <i>qSKC-1</i> was determined precisely by fine mapping. First, the presence of <i>qSKC-1</i> was confirmed by QTL analysis of a re-constructed 'Nipponbare' × 'ZYQ8' F₂ population. Then, F₂ plants in which recombination events had occurred near <i>qSKC-1</i> were identified from the 'Nipponbare' × 'ZYQ8' and <i>rss4</i> × 'ZYQ8' F₂ populations, and their phenotypic values were confirmed by progeny tests. Eventually, by analyzing recombination events in these recombinants, the <i>qSKC-1</i> locus was mapped precisely to 445 kb between markers RM578 and IM8854. These results will facilitate map-based cloning of the <i>qSKC-1</i> locus.