Genetic Background Effect on QTL Expression of Heading Date and Plant Height and Their Interaction with Environment in Reciprocal Introgression Lines of Rice

Abstract

Expression of quantitative trait is affected by genetic background and environment.Genetic background effect on QTL mapping and QTL by environment interaction for heading date(HD)and plant height(PH)in Beijing and Hainan environments were dissected using a large set of reciprocal introgression lines(ILs)derived from a japonica variety"Lemont"and indica variety"Teqing".The two sets of ILs showed transgressive segregation for the two traits.Total 16 and 17 main-effect QTLs were identified for HD and PH in the two environments,respectively.Among them,only five main-effect QTLs(QHd2,QHd8a,QPh3, QPh5,and QPh12)were detected under the two backgrounds,indicating expression of most main-effect QTLs are specific to genetic background.Three main-effect QTLs(QHd8a,QHd9,and QHd10b)by environment interactions for HD were significantly detected under the two backgrounds,of which that of QHd8a had earlier heading for 2–3 days in Hainan,but delayed heading for 2–3 days in Beijing.Therefore,QHd8a could be considered as an important main-effect QTL for HD.By comparison with the QTL mapping results previously identified in the seven different mapping populations derived from the same parents indifferent environments,some stably expressed main-effect QTLs including QHd3,QHd8a,QPh3,and QPh4 were identified under different backgrounds and environments,suggesting these QTLs could be used in marker-assisted breeding for HD and PH. On the basis of the mapping information,marker-assisted improvement of HD for a rice variety under different environments was deeply discussed.