中文摘要：

利用广谱抗稻瘟病基因Pi9的3′UTR序列设计特异DNA标记pi9utr，通过分子标记辅助选择和连续回交育种实践，改良7份籼稻亲本（316B、金23B、R207、R228、R288、R389、明恢86）的稻瘟病抗性。结果表明：pi9utr是一个高效显性分子标记，除R207外，在其余6份受体亲本与Pi9供体亲本75-1-127间均存在明显而稳定的多态；在室内接种后的316B ×75-1-127 BC4F1群体和R288×775-1-127 BC6F1群体中随机取样，进行稻瘟病抗性表型和基因型鉴定及 Pi9基因表达分析，证明 pi9 utr对两个组合回交后代个体的抗病性辅助选择效率均为100％，且在所有抗病单株中均能检测到Pi9基因的高效表达，在所有感病单株中均没有检测到Pi9基因的表达。利用pi9utr在回交世代中的连续辅助选择，获得了3个组合的BC4F1及3个组合的BC6F2代群体，为选育抗稻瘟病新品种打下了基础。

英文摘要：

To improve blast resistance of seven receptor indica rice lines （316B,Jin23B,R207,R228,R288,R389 and Minghui86）,a DNA marker,pi9utr was developed based on the 3′UTR sequence of the broad-spectrum blast resistance gene Pi9 and marker-assisted selection breeding practice was implemented in this study.The main results were as fol-lows：Pi9utr was a stable polymorphic dominant marker for six of seven tested crosses except R207 ×75 -1 -127.The se-lection efficiency of the pi9utr marker for blast resistance phenotype was 100%,and the Pi9 gene showed high level expres-sion in all resistant plants,according to randomly sampled individuals analyses of two backcross populations,316B ×75 -1-127 BC4F1 and R288 ×75 -1 -127 BC6F1.Pi9utr was employed for marker-assisted selection in consecutive back-cross breeding of the six receptor rice lines,and BC4 F1 populations of three combinations and BC6 F2 populations of others three combinations were obtained,which provided basis for breeding of new rice varieties with blast resistant.