QTL mapping for heading date, leaf area and chlorophyll content under cold and drought stress in two related recombinant inbred line populations (Japonica rice) and meta-analysis

Rice is highly susceptible to drought and cold. The goal of this study was to identify the QTLs affecting the rice heading date (HD), leaf area (LA) and chlorophyll content (CC) under cold and drought stress. A total of twenty-nine and thirty-eight additive QTLs were detected from two crosses of Dongnong422'/Kongyu131' and Xiaobaijingzi'/Kongyu131', respectively. qHD1-7-1, qHD1-7-2, qHD1-2-1, qLA1-7-1, qLA1-6-3 and qCC1-7-1 show adaptive effects under cold treatment, while qHD2-2-3, qHD2-2-2, qLA2-7-3 and qCC2-5-1 were important for explaining the genetic mechanism during drought tolerance. Additionally, nine and five additivexenvironment interaction QTLs were detected for two RILs, respectively. RIL26 and RIL73 were two lines that are associated with cold and drought for HD. 339 QTLs related to HD, CC and LA of rice from database and our research were projected onto the genetic map. Nine cloned genes and nineteen homologous candidate genes related to HD, CC, cold tolerance and drought tolerance were mapped by meta-analysis. These results lay the foundation for the fine mapping of QTLs related to HD, LA and CC for marker-assisted selection.