瓜类枯萎病菌遗传多样性和亲缘关系的SRAP分析

尖孢镰刀菌可造成不同瓜类的枯萎病.为明确不同寄主、不同地区的瓜类枯萎病菌菌株间的遗传多样性及亲缘关系,采用相关序列扩增多态性(SRAP)分子标记技术,对来源于不同地区、不同寄主的95株尖孢镰刀菌的基因组DNA进行多态性扩增.以筛选出的19对引物共扩增出238条带,多态性比率为100%,平均每对引物扩增出12.5个位点和12.5个多态性位点;尖孢镰刀菌苦瓜专化型共扩增出166条带,其中145条为多态性条带,多态性比率为87.4%,平均每对引物扩增出8.7个位点和7.7个多态性位点,说明尖孢镰刀菌的遗传变异较为广泛.瓜类枯萎病菌株间的遗传相似系数范围为0.68～0.99,样品间的平均Nei遗传多样性指数和Shannon指数分别为0.2390和0.3718.在遗传相似系数为0.74时,可将供试的95株尖孢镰刀菌划分为苦瓜、黄瓜、西瓜、甜瓜4个专化群.在SRAP聚类树中,同一寄主的尖孢镰刀菌聚在一个分支上,其中尖孢镰刀菌苦瓜专化型菌株间的遗传相似系数范围为0.78～0.99,Nei遗传多样性指数为0.1811,平均Shannon指数为0.2750,表明尖孢镰刀菌苦瓜专化型的遗传变异较大,且菌株的聚群与地理来源存在相关性.

Genetic diversity and phylogenetic analysis of Fusarium oxysporium strains isolated from the Cucurbitaceae hosts revealed by SRAPs

Cucurbitaceae wilt of different hosts could be caused by Fusarium oxysporum. To clear the genetic diversity and phylogenetic relationship of F. oxysporum isolates from different Cucurbitaceae hosts and regions, genomic DNA of ninety-five strains of F. oxysporum isolated from different hosts and different regions were amplified by sequence-related amplified polymorphism (SRAP) molecular markers. All strains could be uniquely distinguished with 238 polymorphism bands which generated 100% of polymorphic ratio with 19 selective primer pairs. On average, each primer pairs amplified 12.5 loci and 12.5 polymorphic loci. A total of 166 bands of F. oxysporum f. sp. momordicae (FOM) were amplified, among which 145 polymorphic bands generated 87.4% of polymorphic ratio. On average, each primer combination amplified 8.7 loci and 7.7 polymorphic loci. This indicated that genetic variation of F. oxysporum was extensive. The genetic similarity coefficient of F. oxysporum was 0.68-0.99, and the average indexes of Nei’s genetic diversity and Shannon were 0.2390 and 0.3718, respectively. Ninety-five strains of F. oxysporum were divided into four formae speciales from bitter gourd, cucumber, watermelon and melon, when the genetic similarity coefficient was 0.74. In SRAP dendrogram all the FOM isolates were gathered into one phylogenetic branch with the genetic similarity coefficient ranging from 0.78 to 0.99. The average indexes of Nei’s genetic diversity and Shannon indices were 0.1811 and 0.2750, respectively. This indicated that genetic diversity of FOM was abundant, and the classification of phylogenetic group was related to geographic origin to some extent.