蔓枯病是甜瓜生产上危害严重且普遍发生的一种土传病害，利用抗病基因培育抗病品种被认为是控制该病危害最经济有效的措施。目前，甜瓜中尚未精细定位和克隆任何蔓枯病抗性基因。在前期研究中，我们从抗源4G21中鉴定并初步定位了一个新的蔓枯病抗性基因Gsb-7(t)。本项目拟精细定位该基因，分析定位区间内基因序列以确定候选基因，并利用转基因手段验证候选基因的功能；同时开发与目的基因紧密连锁的或者功能特异性的分子标记，建立该基因的分子标记辅助选择育种体系。研究结果不仅可以丰富甜瓜蔓枯病抗源、抗病基因库，为高效利用Gsb-7(t)基因开展甜瓜抗蔓枯病分子育种提供新的手段，而且有望首次克隆甜瓜蔓枯病抗性基因，为深入解析其作用机制奠定基础。

Gummy stem blight (GSB), caused by Didymella bryoniae (Anersw.) Rehm, is a destructive soil-borne foliar fungal disease of melon (Cucumis melon L.) worldwide. The utilization of host resistance (R) genes or resistant cultivars is considered to be the most economic and effective strategy to control this disease. However, there are no reports on fine-mapping and cloning of GSB resistance genes on melon. We previously characterized a new broad-spectrum resistant cultivar 4G21 and identified and roughly mapped a new GSB resistance gene Gsb-7(t). In this project, we will finely map the Gsb-7(t) gene by map-based cloning and candidate gene sequencing strategies, determine the functions of Gsb-7(t) candidates through gene transformation approaches. Additionally, we will develop tightly linked or functional markers (FMs) of Gsb-7(t) in order to facilitate the application of Gsb-7(t) in melon breeding programs. This project aims to not only enrich resistant source and resistance gene pool, and provide new means to develop new GSB resistant cultivars by molecular breeding, but also clone the Gsb-7(t) gene, and lays foundation for further elucidating the Gsb-7-mediated defense mechanisms.