西甜瓜果斑病菌avrRxo1同源基因激发玉米Rxo1抗性产生的研究

Study on Rxo1 resistance in maize elicited by avrRxo1 homologous gene of Acidovorax citrulli

生物信息学分析发现西(甜)瓜果斑病菌(Acidovorax citrulli,Ac)基因组中存在水稻条斑病菌(Xanthomonas oryzae pv.oryzicola,Xoc)avrRxo1的同源基因avrRxo1_(Ac)。为了揭示avrRxo1_(Ac)是否能够激发玉米R基因Rxo1介导的过敏反应(Hypersensitive response,HR),本研究克隆了avrRxo1_(Ac)基因;氨基酸同源性分析结果显示:AvrRxo1_(Ac)与AvrRxo1的同源性为53.16%。将avrRxo1_(Ac)置于Xoc的avrRxo1突变体中,发现其不能恢复该突变体在含有Rxo1玉米上激发HR反应的能力;借助农杆菌瞬时表达体系发现AvrRxo1A,也不能在Rxo1玉米上激发HR反应。这些结果表明avrRxo1_(Ac)-Rxo1互作不表现为基因-对-基因关系,暗示Rxo1抗病基因转入西甜瓜中,将不能起到抗西(甜)瓜细菌性果斑病的作用。

Bioinformatics analysis found that there is an avrRxo1 homologous gene of Xanthomonas oryzae pv.oryzicola in the genome of Acidovorax citrulli strain,designated avrRxo1Ac.In order to reveal whether avrRxo1Accan trigger a specific hypersensitive response（HR） on maize with a resistance（R） gene Rxo1.The avrRxo1Acgene was cloned in this study.Amino acid comparison analysis showed that AvrRxo1Ac and AvrRxo1 have 53.16%identity.The Xoc avrRxo1 mutant did not restore the ability to elicit a HR on maize with Rxo1 when complemented with avrRxo1c） gene.Transient expression of avrRxo1Ac gene in maize lines carrying Rxo1 mediated by Agrobacterium did not result in a HR.Taken together,avrRxo1-Rxo1 interaction copes with gene-for-gene relationship,suggesting that Rxo1 genes would not exhibit resistance to Acidovorax citrulli strains when genetically transferred into watermelon or melon plants.