利用回交导入系定位干旱环境下水稻植株水分状况相关QTL

日益严重的水资源危机使水稻的耐旱育种尤为迫切, 干旱环境下较高的植株水分含量有助于提高或维持作物产量的稳定性, 挖掘与耐旱性密切相关的分子标记有助于提高耐旱品种的选育效率。从供体Lemont (粳稻)导入到特青(籼稻)背景的254个高代回交导入系中筛选出覆盖供体全基因组的55个回交导入系, 采用PVC管栽培, 分析了干旱(胁迫)条件下水稻植株水分状况相关性状与籽粒产量、生物量的相关性并定位了相关QTL。研究表明, 植株水分相关性状(相对含水量、叶片水势、渗透势、卷叶度)均与籽粒产量显著相关。检测到7个相对含水量QTL, 7个叶片水势QTL, 5个渗透势QTL及5个卷叶QTL; 另检测到5个产量QTL, 7个生物量QTL。分析发现, 不仅QLwp5、QLr5、QRwc5和QY5同时分布在RM509~RM163区域, 且该区域还分布有对水分环境表现稳定的产量QTL(QGy5), 效应方向一致, 从遗传学角度解释了籽粒产量与水分相关性状之间的显著相关性。另外, QLr5、QRwc5、QY5、QLr2、QLr7、QLr8、QLr9、QRwc3、QRwc4a、QRwc12及QY7 等11个QTL曾在不同遗传背景群体中被检测到, 它们控制相同目标性状。研究认为RM509~RM163区域及QLr2、QLr7、QLr8、QLr9、QRwc3、QRwc4a、QRwc12和QY7所分布的染色体区域对水分环境或者遗传背景相对稳定, 在水稻分子标记辅助选择(MAS)耐旱育种实践中有较重要利用价值。

Locating QTLs for Plant Water Status under Drought Condition in Over-lapping Introgression Lines of Rice (Oryza sativa L.)

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.