Minor-effect QTL for heading date detected in crosses between indica rice cultivar Teqing and near isogenic lines of IR24
Zhichao Sun, Yujun Zhu, Junyu Chen, Hui Zhang, Zhenhua Zhang, Xiaojun Niu, Yeyang Fan and Jieyun Zhuang*
The Crop Journal
,?2018, 6(3):291-298
DOI:10.1016/j.cj.2018.01.002
Abstract
Identification of quantitative trait loci (QTL) having small effects on heading date (HD) is important for fine-tuning flowering time in rice (Oryza sativa L.). In this study, minor-effect QTL for HD were identified using five segregating rice populations, including a recombinant inbred line population derived from crosses between indica cultivar Teqing and near isogenic lines of IR24, and four populations derived from residual heterozygotes identified in the original population. HD data from these populations were obtained in multiple years or at two locations with different photoperiods. A total of 11 QTL were detected; they had small additive effects ranging from 0.21 to 1.63 days. The QTL were all detected in different populations, locations and/or years, having consistent allelic effects across experiments and a stable magnitude across years at the same location. These QTL, and other minor-effect QTL that have been cloned or fine-mapped, generally do not have strong photoperiod sensitivity, and thus can be used in a wide range of eco-geographical conditions. Seven of the 11 QTL were different from those that have been cloned or fine-mapped, providing new candidates for gene cloning and marker-assisted breeding. Allelic effects of QTL corresponding to those that had been cloned or fine-mapped, were much smaller in this study than previously reported. The results supported the assumption that qualitative and quantitative genes may be different alleles at the same loci, suggesting that it may be promising to identify minor-effect QTL from major heading date genes/QTL that have been cloned.