抗番茄疮痂病新基因Rx5(t)的克隆和分子调控机理

番茄疮痂病由黄单胞杆菌属的多个种和小种引起，在同一地区不同种和小种同时存在，更替频繁，而目前已经鉴定到的抗性资源相对较少，导致育种中可利用的抗性基因也少，给抗病育种和病害综合防治带来巨大挑战。本课题组最近从醋栗番茄中发现了一个新的抗病材料LA2401，遗传分析表明其抗性由一对显性基因控制，初步定位结果显示，该基因与所有已知抗番茄疮痂病的基因不同，为新基因，暂时命名为Rx5(t)。本项目拟对Rx5(t)基因进行精细定位，图位克隆获得该基因，采用遗传转化互补和基因编辑确定基因的功能；分析与新基因Rx5(t)和已知基因Rx4互作的番茄基因和病原菌无毒基因，比较Rx5(t)和Rx4的抗性调控机理；同时，建立Rx5(t)基因的功能分子标记辅助选择体系，构建携带Rx5(t)基因的近等基因系。本项目的实施可为系统研究番茄疮痂病的抗性机理和培育抗病品种提供新的基因资源和材料。

Bacterial spot of tomato is caused by multiple species and races of Xanthomonas spp. Different species and races can exist simultaneously and change frequently in the same region. To date, there are relatively few resistant sources have been identified, resulting in less resistance genes available in breeding, which brings great challenges to disease resistance breeding and integrated management of the disease. Recently, we identified a novel resistant accession LA2401 from Solanum pimpinellifolium. Genetic analysis indicated that the resistance in the line is conditioned by one single dominant gene. Based on the preliminary mapping position, the resistance in LA2401 is conditioned by a novel gene because it is different from all known genes for resistance to bacterial spot in tomato, and thus is temporarily designated as Rx5(t). The project described here is intended to conduct fine mapping and map-based cloning of the gene. Transgenic and gene editing approaches will be applied to validate its function. Genes in tomato and avirulence genes in the bacteria that interact with Rx5(t) and a known resistance gene Rx4 will be identified for comparing the resistance mechanisms between Rx5(t) and Rx4. Meanwhile, marker-assisted selection system for Rx5(t) will established and near iso-genic lines carrying the Rx5(t) will be developed. This project will help systematically understand mechanisms of resistance to bacterial spot in tomato, and provide a novel gene and plant materials for developing resistance cultivars.