Fine mapping and candidate gene analysis of qHD1b, a QTL that promotes flowering in common wild rice (Oryza rufipogon) by up-regulating Ehd1
Ling Liu,
Yingxin Zhang,
Zhengfu Yang,
Qinqin Yang,
Yue Zhang,
Peng Xu,
Jiaxin Li,
Anowerul Islam,
Liaqat Shah,
Xiaodeng Zhan,
Liyong Cao,
Shihua Cheng,
Weixun Wu
Affiliations
Ling Liu
China National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China
Yingxin Zhang
China National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China
Zhengfu Yang
State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, Zhejiang, China
Qinqin Yang
China National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China
Yue Zhang
China National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China
Peng Xu
China National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China
Jiaxin Li
China National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China
Anowerul Islam
China National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China
Liaqat Shah
China National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China
Xiaodeng Zhan
China National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China
Liyong Cao
China National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China; Northern Center of China National Rice Research Institute, Hangzhou 310006, Zhejiang, China
Shihua Cheng
China National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China; Corresponding authors.
Weixun Wu
China National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China; Corresponding authors.
Heading date (flowering time) determines the adaptability of cultivars to different environments. We report the fine mapping and candidate gene analysis of qHD1b, a quantitative trait locus (QTL) responsible for early flowering that was derived from common wild rice (O. rufipogon) under both short-day and long-day conditions. The introgression line IL7391, which carried segments from common wild rice in a Zhonghui 8015 (ZH8015) background, exhibited early heading compared to the background and was crossed with ZH8015 to generate BC5F2:3 families for QTL analysis. This enabled the identification of two heading-date QTL, named qHD1b and qHD7, of which the first was selected for further research. High-resolution linkage analysis was performed in BC5F4:5 and BC5F6 populations, and the location of qHD1b was confined to a 112.7-kb interval containing 17 predicted genes. Five of these genes contained polymorphisms in the promoter or coding regions and were thus considered as candidates. Expression analysis revealed a positive association between LOC_Os01g11940 expression and early heading. This locus was annotated as OsFTL1, which encodes an ortholog of Arabidopsis Flowering Locus T and was the most likely candidate gene for qHD1b. Our study revealed that qHD1b acts as a floral activator that promotes flowering by up-regulating Ehd1, Hd3a, RFT1, OsMADS14, and OsMADS15 under both short-day and long-day conditions. Field experiments showed that qHD1b affected several yield-related agronomic traits including 1000-grain weight and grain length. qHD1b could be useful for marker-assisted selection and breeding of early-maturing cultivars.
