利用高代回交导入系定位水、旱条件下影响水稻根系及产量的QTL

QTL Mapping of Yield and Root Traits Under Irrigation and Drought Conditions Using Advanced Backcrossing Introgression Lines in Rice

严重的水资源危机使得水稻耐旱性的遗传与育种研究成为当今的研究热点之一。【目的】鉴定与水稻耐旱性直接相关的根系性状QTL,为通过根系性状QTL的标记辅助选择培育耐旱水稻品种提供标记信息。【方法】以从供体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个回交导入系为材料,采用PVC管栽培,定位了灌溉(对照)与干旱(胁迫)条件下影响根系及产量性状的QTL以及胁迫与对照间性状差值的QTL。【结果】共检测到25个影响根长(RL)、根数(RN)、根重(RW)和单株粒籽产量(GY)的主效QTL,根据在不同环境下的表达情况,将其分为3类,第1类4个,在两种环境下均被检测到;第2类12个,只在对照条件下检测到;第3类9个,受干旱胁迫诱导,只在胁迫条件下被检测到。此外还检测到11个影响胁迫与对照条件下性状差值的QTL。【结论】在水、旱两种条件下均检测到的相对稳定的3个QTL(QRl2b、QRl8b、和QRn12)及影响两种条件下性状差值(即性状稳定性)的11个QTL可能对耐旱性有直接贡献。

[ Objective] In rice breeding research, drought tolerance （DT） is becoming one of the most important target traits for variety improvement under ever-increasing severe drought situation in the whole world. Identification of the root character QTLs which are directly related to DT will provide useful marker information for development of DT rice variety via marker-assisted selection （MAS） against the root QTL. [Method] The 55 introgression lines （ILs） selected from 254 advanced backcross introgression population derived from Lemont/Teqing in the Teqing background were planted in PVC pipe in solarium and phenotyped for root characters and grain yield under irrigation and drought stress conditions. QTLs affecting root length （RL）, root number （RN）, root weight （RW）, grain yield （GY） and their stability of expression in both drought and water conditions were identified. [Result] A total of 25 main-effect QTL for the four traits were identified, which can be grouped into three types based on their behaviors. Type Ⅰ included four QTLs which were detected both under two conditions; type Ⅱ consisted of 12 QTLs which were mapped only at the control condition; and type Ⅲ consisted of nine QTLs which were induced by drought and detected only under the stress. In addition, eleven QTLs （QGy6, QGy8, QGy12, QR18a, QR112, QRn11, QRn12, QRw1a, QRw1b, QRw7 and QRw12a） affecting trait differences between stress and control were identified. [ Conclusion ] There were three QTLs （QR12b, QR18b and QRn12） which expressed in both of the two environments with same direction and magnitude of gene effect. These three root-QTLs and other eleven QTLs affecting trait differences were considered to directly contribute to DT. The results will provide useful information for fine-mapping of DT-related root QTL and DT rice breeding by MAS.