番茄疮痂病是由黄单胞杆菌属多个种引起的一种细菌性病害，目前生产上还没有抗性品种和有效的防治药物，因此该病害一旦暴发，就会严重影响露地和保护地的番茄生产。在我国，番茄疮痂病病原菌存在4个种和3个小种。T1是最早发现的一个小种，番茄材料对该小种的抗性呈数量性状遗传，虽然已经从抗性材料Hawaii7998中鉴定到一个主效抗性位点Rx3，但由于缺乏可靠的分子标记，因此在实际育种中应用存在一定难度。为此，本项目拟对Rx3位点进行克隆，通过VIGs、瞬时表达和功能互补试验等技术对Rx3位点进行功能验证，并采用RNA-seq技术、结合对高回交世代群体和近等基因系的构建分析，分离和鉴定对Rx3的表达具有调控作用的基因，以阐明Rx3位点对T1小种的抗性及调控机制，同时建立T1小种抗性位点Rx3的功能分子标记辅助选择体系，为番茄疮痂病抗性分子育种提供理论基础。

Tomato bacterial spot is a bacterial disease caused by multiple species of Xanthomonas. The outbreak of the disease will severely affect tomato production in open and protected fields due to the lack of resistant varieties and efficient chemicals for controlling the disease. Four species and three races have been reported in China. Race T1 is the earliest race reported. The resistance to this race in tomato lines is quantitatively inherited. Although one major locus Rx3 has been identified from the resistant line Hawaii7998, it is difficult to use it in breeding programs because the marker linked to the locus is not always reliable. Therefore, this project proposed here intends to clone the Rx3 locus, to verify the function of the locus Rx3 for resistance to race T1 using VIGS, transient expression and complementary experiment, and to isolate genes regulating the expression of Rx3 using RNA-seq combining construction of advanced backcross population and near-isogenic lines. These will allow us to illustrate the mechanism and regulation of resistance to race T1 of bacterial spot at the Rx3 locus, and develop functional molecular markers for marker-assisted selection of Rx3. All results obtained in this project will provide some fundamental basis to molecular breeding for resistance to bacterial spot in tomato.