用水稻抗白葉枯病基因Xa23的近等基因系CBB23 與其感病輪回親本JG30雜交，構(gòu)建了包含2562個(gè)單株的F2作圖群體?？剐澡b定表明，F(xiàn)2植株抗感分離比嚴(yán)格符合3:1。根據(jù)日本水稻基因組計(jì)劃RGP 的數(shù)據(jù)，篩選并合成12個(gè)EST標(biāo)記的引物，進(jìn)行親本間多態(tài)性檢測(cè)，找到2個(gè)在CBB23與JG30間有多態(tài)性的EST標(biāo)記，C189和CP02662。用該標(biāo)記對(duì)F2群體中的571個(gè)感病單株進(jìn)行分子檢測(cè)和連鎖分析，結(jié)果表明這兩個(gè)EST標(biāo)記位于Xa23基因的兩側(cè)，C189靠著絲粒一側(cè)，與Xa23的遺傳距離為0.8cM；CP02662靠端粒一側(cè)，與Xa23的遺傳距離為1.3cM。將C189成功用于水稻分子育種實(shí)踐，標(biāo)記輔助選擇的正確率接近100%，已培育出3個(gè)將Xa23基因與高產(chǎn)、優(yōu)質(zhì)、抗褐飛虱等性狀聚合的水稻恢復(fù)系。
A F2 population, with 2 562 individuals, of JG30/CBB23 was constructed for molecular mapping of the bacterial blight resistance gene Xa23 in rice. Inoculation test of the F2 plants showed that the segregation ratio of resistant and susceptible fits to 3:1. Based on the amthors previous mapping of Xa23 gene, 12 EST markers from Rice Genome Program (RGP) database were surveyed in the susceptible F2 plants and two markers, C189 and CP02662, were found flanking the Xa23 gene, with genetic distance of 0.8cM and 1.3cM, respectively. These two EST markers were successfully used in rice breeding program. The results showed that efficiency of C189 marker-assisted selection (MAS) for Xa23 gene was almost 100%. Three elite hybrid rice restore lines with Xa23 gene and improved bacterial blight resistance have been developed.