水稻抽穗期QTL DTH2的精细定位和候选基因预测

Heading date (HD) in rice is a key determinant for its adaptation to different cultivation zones and cropping seasons. Here, we discover a newly identified minor-effect QTL DTH2, which promotes flowering only under long-day conditions (LDs). A genetic effect of dth2 was first confirmed in the chromosome segment substitution line 23 (CSSL23), then the QTL was mapped using the CSSL23/Asominori BC4F2 population. One nearly isogenic line (NIL) was developed from the BC4F2 population using a marker-assisted selection strategy. Map-based cloning located the DTH2 in a 37.6-kb genomic region with 9 predicted open reading frames (ORFs), of which ORF5 showed 51% amino-acid-sequence identity with the Arabidopsis COL9, which delays flowering by reducing expression of CO and FT in Arabidopsis only under long-day conditions. We speculated that ORF5 was the candidate gene. This study provides a basis for map-based cloning of the DTH2 gene.