水稻R基因同源序列与遗传学上已知抗病基因的共定位(英文)

植物抗病（R）基因结构上的高度保守性，为利用基于PCR的方法快速分离R基因同源序列提供了基础。采用这种方法，我们曾从水稻中分离到8个R基因候选同源序列（Rgenecandidates，RGCs）。为了研究RGCs与遗传学上已知的R基因的关系，对它们进行了限制性片段长度多态性（RFLP）分析和染色体定位。DNA杂交结果显示RGCs都属于多基因家族（Fig．1）。6个RGCs（Osh359－1、Osh359－2、Osh359－3、Osh359－5、Os8558－3、Os8558－14）在两个籼稻品种H359和Acc8558中检测出多态性，并定位在水稻染色体上（Fig．2）。它们分别检测出了1、1、4、1、2和1个座位，共10个座位，其中9个定位在第11号染色体的3个区域上，即RFLP标记G181和C82之间（由Osh359－2、Osh359－3、Osh359－5和Os8558－3检测的6个座位），G1465与C50之间（Osh359－3检测出的一个座位），和C496附近（由Osh359－1和Os8558－14检测出的两个紧密连锁的座位）另有一个由Os8558－3检测出的座位定位到第8号染色体上，位于L457和G1082B之间。这些染色体区域包含近一半的遗传学上已知的抗病基因，如Xa-3、Xa－10、Pi－a和xa－13。这一结果表明RGCs与已知的抗病基因位于相同的染色体区域。此外，RGCs定位的结果表明，它们在水稻基因组中呈簇状分布，表现出

Co-localization of Resistance Gene Candidates with Genetically Known Disease Resistance Genes in Rice

Plant disease resistance (R) genes show remarkable structuralconservation offering a polymerase chain reaction (PCR)-based approach to rapidlyisolate R gene candidates (RGCs). Previously, we isolated eight RGCs from rice cultivarsH359 and Ace8558. In order to investigate their relations to genetically identified Rgenes in rice, analysis on restriction fragment length polymorphism (RFLP) was done onthe RGCs. Six out of the eight RGCs, Osh359-1, Osh359-2, Osh359-3, Osh359-5, Os85583 and Os8558-14, were localized on rice chromosomes. These sequences detected the 1, 1,4, 1, 2 and 1 loci, respectively. Nine out of the ten loci were positioned in three regions ofchromosome 11. The first region included a total of six loci detected by Osh359-2,OSh359-3, Osh359-5 and Os8558-3, which were localized betWeen RFLP markers G181and C82; the second had one locus also revealed by Osh359-3 and was close to G1465; thethird contained tWo tightly linked loci detected respectively by Os8558-14 and Osh359-1,close to C496. One additional locus on chromosome 8 was detected by Os8558-3between L457 and G1082B. These chromosomal regions correspond to nearly half ofthe genetically known R genes represented respectively by Xa-3, Xa-21, Pi-a and xa-13strongly indicating that the RGCs and them are co-localized. Furthermore, the mappingof RGCs shows that they are grouped together to form clusters, showing a featureconsistent with the rapid generation of disease resistance specificity of R genes.