Effect of Genetic Background on QTLs for Heading Date and Plant Height and Interactions Between QTL and Environment Using Reciprocal Introgression Lines in Rice

Expression of quantitative trait locus (QTL) is affected by genetic background (GB) and environment. The GB effect on QTL mapping and QTL by environment interaction for heading date (HD) and plant height (PH) were studied in Beijing and Hainan environments using a large set of reciprocal introgression lines (ILs) derived from a japonica rice (Oryza sativa L.) variety Lemont and an indica variety Teqing. In both environments, the 2 IL populations showed transgressive segregation for HD and PH traits. A total of 16 and 17 main-effect QTLs (M-QTLs) were identified for HD and PH, respectively. Among them, only 5 M-QTLs were detected under the 2 GBs, indicating that the expressions of most M-QTLs are specific to GB. Under both GBs, significant interactions between QTLs and environment responsible for HD were observed at 3 M-QTLs, of which QHd8a antedated heading for 2–3 d in Hainan but delayed heading for 2–3 d in Beijing. Therefore, QHd8a could be considered as an important M-QTL for HD. By comparing with the previous results on QTL mapping using another 7 populations derived from the same parents, a few M-QTLs were found to express stably under different GBs in various environments, such as QHd3, QHd8a, QPh3, and QPh4. These QTLs show applicable potential in marker-assisted breeding for HD and PH in rice.