尖镰孢菌EST-SSR遗传多样性分析及通用性评价
Analysis of genetic diversity and cross-species transferability based on Fusarium oxysporum EST-SSR markers

为了解38株尖镰孢菌的遗传多样性并开发可在近缘镰孢菌种中通用的尖镰孢菌EST-SSR标记,利用设计和筛选的18对多态性EST-SSR引物对38株尖镰孢菌和5种近缘镰孢菌进行SSR-PCR扩增,经6%非变性聚丙烯酰胺凝胶分离扩增产物,并用NTSYS软件分析供试尖镰孢菌的PCR扩增结果。结果表明,18对EST-SSR标记引物在38株尖镰孢菌中检测到75条多态性条带,多态性比率达92.6%,平均每对引物可扩增4.2条;各菌株间的遗传相似系数介于0.565~0.946之间,平均为0.721;来源于同科寄主植物群体的菌株间的平均遗传相似系数以葫芦科最大,锦葵科最小,依次为葫芦科 >兰科 >豆科 >亚麻科 >茄科 >锦葵科。在相似系数为0.756时,供试38株菌有35株按照不同科寄主植物聚为不同的类群,说明尖镰孢菌SSR类群的划分与其寄主来源具有一定的相关性。18对EST-SSR引物在近缘镰孢菌种中均能有效扩增的引物数及通用性比率为10对和55.6%,均显示多态性的引物有2对,占供试引物总数的11.1%。表明尖镰孢菌EST-SSR区域遗传多样性丰富,基于尖镰孢菌EST序列开发镰孢菌通用SSR标记是可行的。
The objective of this study is to analyze genetic diversity of 38 Fusarium oxysporum strains and to develop F. oxysporum EST-SSR markers which can be also used in other Fusarium spp. strains. Eighteen EST-SSR markers were used to assess Fusarium spp. strains and the amplification products were separated on 6% denatured polyacrylamide gels. Then the resulting data was analyzed using NTSYS program. The results showed that a total of 75 (92.6%) bands were amplified by 18 primers with an average of 4.2 bands per marker. The genetic similarity among all the strains ranged from 0.565 to 0.946 with an average of 0.721. The average genetic similarity among the strains of different families was different; those of the strains from Cucurbitaceae family showed the highest similarity, those from Malvaceae the lowest, and the order was Cucurbitaceae >Orchidaceae >Leguminosae >Linaceae >Solanaceae >Malvaceae. Phylogenetic clustering based on these 18 EST-SSR markers showed that 35 F. oxysporum strains were distinctly clustered into different groups according to their host family at 0.756, which indicated some correlation between clustering and host origins of strains. The pairs of primers that could effectively amplified bands in five Fusarium spp. strains were ten, and the transferability rate was 55.6%. A total of two pairs (11.1%) of F. oxysporum EST-SSR primers were detected to be highly polymorphic among Fusarium spp. These results indicated that F. oxysporum had a rich genetic basis and exploitation of EST-SSR markers from F. oxysporum for other Fusarium spp. was efficient.