Jiang G H, Wang W M, Xie B, Zhai W X, Lu R L, Zhu L H
Institute of Genetics, Chinese Academy of Sciences, Beijing 100101, China.
Yi Chuan Xue Bao. 2001;28(3):236-43.
The gene Xa4 confers dominantly resistance to rice bacterial blight, which has been finely mapped between RFLP markers G181 and L1044, and co-segregated with the resistance gene homologues sequence marker RS13. The three markers were used to screen a rice Bacterial Artificial Chromosome (BAC) library constructed from IRBB56, a Xa4-harborring indica variety, resulting in the detection of totally 128 positive clones. Of the 18 positive clones picked out by RS13, 4 and 6 clones were simultaneously detected by G181 and L1044, respectively. Based on their HindIII restriction patterns, 12 clones were selected out to construct a contig that spanned about 420 kb covering the Xa4 locus, which is a solid base for the isolation of Xa4 gene.
Xa4基因对水稻白叶枯病具有显性抗性，该基因已被精细定位在RFLP标记G181和L1044之间，并与抗性基因同源序列标记RS13共分离。利用这三个标记对由携带Xa4基因的籼稻品种IRBB56构建的水稻细菌人工染色体（BAC）文库进行筛选，共检测到128个阳性克隆。在RS13挑选出的18个阳性克隆中，分别有4个和6个克隆同时被G181和L1044检测到。根据它们的HindIII酶切图谱，挑选出12个克隆构建了一个覆盖约420 kb、包含Xa4基因座的重叠群，这为分离Xa4基因奠定了坚实基础。
