西瓜枯萎病菌生理小种1抗性基因连锁标记开发

【目的】开发与栽培西瓜枯萎病菌生理小种1抗性基因Fon-1紧密连锁的分子标记，为开展西瓜抗枯萎病分子辅助育种提供技术支撑。【方法】以栽培西瓜抗枯萎病品种Calhoun Gray为父本，感病品种Black Diamond为母本杂交获得的F2分离群体为供试材料，采用BSA法对Fon-1基因进行区间定位。依据11份栽培西瓜重测序信息，获取位于定位区间内的候选SNP位点。针对候选SNP位点设计CAPS/dCAPS标记，通过F2代分离群体和种质资源验证上述标记与Fon-1基因的连锁关系。【结果】通过BSA法，将Fon-1基因定位于1号染色体15 cM区间内。利用候选SNP位点信息，开发3个CAPS/dCAPS标记7716_fon、7419_fon和4451_fon，F2代分离群体以及164份西瓜育种材料验证显示，上述3个标记与Fon-1基因的连锁距离分别为0.8、1.0和2.8 cM。【结论】利用栽培品种Calhoun Gray的抗性遗传机制,开发的3个CAPS/dCAPS标记可以有效区分栽培西瓜对枯萎病菌生理小种1的抗病、感病性，为栽培西瓜品种枯萎病菌生理小种1抗性基因快速应用于栽培品种枯萎病抗性改良建立有效的技术手段。

Developments of Molecular Markers Tightly Linked to Fon-1 for Resistance to Fusarium oxysporum f. sp. niveum Race 1 in Watermelon

【Objective】 In order to provide technical support for molecular marker-assisted breeding for Fusarium wilt resistance in watermelon, molecular markers tightly linked to Fon-1 for Fusarium oxysporum f. sp. niveum race 1 resistance were developed.【Method】An F2 segregating population derived from a cross between the cultivated resistant male parent ‘Calhoun Gray’ and the susceptible female parent ‘Black Diamond’. The bulked segregant analysis (BSA) was employed to map the Fon-1 gene interval preliminaryly. A series of candidate single nucleotide polymorphism (SNP) sites that are linked to the target traits were obtained, and resequencing analysis within the target gene interval among 11 cultivated watermelon accessions was conducted. And then, the cleaved amplified polymorphic sequence (CAPS) or derived cleaved amplified polymorphic sequence (dCAPS) markers were designed to verify the linkage relationship between these CAPS/dCAPS marker and Fon-1 gene using F2 segregating population and germplasm resources. 【Result】 The preliminary results from screening of the resistant and susceptible DNA pools with 950 pairs of SSR/Indel/dCAPS primers mapped the Fon-1 gene to a 15 cM interval of watermelon chromosome 1. Three markers, 7716_fon, 7419_fon and 4451_fon, which were demonstrated to be tightly linked to Fon-1 gene, were developed using the SNP sites confirmed in the F2 population and 164 cultivars and the genetic distance between the markers and the Fon-1 gene was estimated to be 0.8 cM, 1.0 cM and 2.8 cM, respectively.【Conclusion】Three CAPS/dCAPS markers that can effectively distinguish the resistance/susceptibility to Fusarium oxysporum f. sp. niveum race 1 in cultivated watermelon were developed in this study and these markers will provide useful technical support for molecular breeding for resistance against F. oxysporum f. sp. niveum race 1 in cultivated watermelon.