Abstract: Drought tolerance (DT) is becoming one of the most important target traits in rice variety improvement under ever-increasing severe drought situation all over the world and identifying genomic regions contributing to DT will help to develop cultivars suitable to drought environments. The maintenance of higher plant water status are known to contribute to increase yield and yield stability under drought in cereals. In present study, the relationship between the traits related to plant water status and grain yield (GY) was analyzed and the quantitative trait loci (QTLs) linked to target traits were mapped by means of 55 introgression lines (ILs) selected from 254 advanced backcross introgression population derived from Lemont/Teqing in the Teqing background. The ILs and parents were planted in PVC pipes in screen house and phenotyped under drought and/or irrigation conditions. Significant phenotypic correlation between GY and the traits related to plant water status was observed. QTLs related to plant water status were identified which included seven for relative water content (RWC), seven for leaf water potential (LWP), five for osmotic potential (Y) and five for leaf rolling (LR) under drought condition, moreover, five QTLs for grain yield (GY) and five QTLs for biomass (BM) were detected under both drought and control conditions. By comparing the coincidence of QTLs with specific traits, we genetically dissected the nature of association among different traits related to plant water status and the association between GY and plant water status under drought. This study demonstrated that the region RM509–RM163 on chromosome 5 identified for plant water status-related DT component QTLs also had pleiotropic effects on yield under stress and control conditions. Moreover, the eleven QTLs, QLr5, QRwc5, QY5, QLr2, QLr7, QLr8, QLr9, QRwc3, QRwc4a, QRwc12, and QY7 controlling the same traits were detected in different genetic populations which means these regions were relatively stable to the environment or/and genetic backgrounds. The consistent QTLs for plant water status under stress might be useful for marker as-sisted selection (MAS) breeding in rice for DT improvement.

Key words: Rice, Drought, Plant water status, Backcross introgression lines, Quantitative trait locus