番茄3个抗疮痂病菌T3小种基因的等位性测定和序列分析

将分别携带抗番茄疮痂病菌Xanthomonas perforans T3小种基因Xv3、Rx4和RxLA1589的番茄材料Hawaii7981、PI128216和LA1589相互杂交，获得了包含535 ~ 1 655个单株的3个F2分离群体 Hawaii7981 × PI128216、Hawaii7981 × LA1589和PI128216 × LA1589。采用注射法对这3个F2群体的每个单株及亲本和感病对照OH88119进行抗T3小种鉴定，结果显示除OH88119外的所有单株对T3小种都具有过敏型抗性反应，表明Xv3、Rx4和RxLA1589为等位基因。根据Rx4基因的序列设计引物，从Hawaii7981、PI128216和LA1589中扩增该基因并测序，序列比对显示，来自于3个材料的Rx4位点编码区序列完全一致，表明这3个材料所携带的对番茄疮痂病菌T3小种的抗性由同一基因控制。

Allelic Tests and Sequence Analysis of Three Genes for Resistance to Xanthomonas perforans Race T3 in Tomato

Three crosses，Hawaii7981 × PI128216，Hawaii7981 × LA1589 and PI128216 × LA1589，were made to develop F2 populations for testing allelisms among three genes Xv3，Rx4，and RxLA1589 for resistance to bacterial spot caused by Xanthomonas perforans race T3. Each population consisted of 535–1 655 individuals. Infiltration method was used to inoculate the parental and F2 plants as well as the susceptible control OH88119. The results showed that all plants had hypersensitive resistance to race T3 except for OH88119，indicating that Xv3，Rx4 and RxLA1589 were allelic genes. Sequences of Rx4 alleles were amplified from Hawaii7981，PI128216，and LA1589 using the gene-specific primers. No sequence variation was observed in the coding region，suggesting that the resistance to race T3 in the three resistant lines was conditioned by the same gene. These results will provide useful information for understanding the mechanism of resistance to race T3 and developing resistant variety in tomato.