Genetic Diversity And Phylogenetic Study Of Plant Pathogenic Fusarium

Fusarium is an important pathogenic fungus that can cause a variety of plant diseases.In this study,The Fusarium oxysporum strains were used as the research object.Based on the bioinformatics method,the SSR loci of Fusarium oxysporum were analyzed,and the SSR primers were used to analyze the SSR genetic diversity of Fusarium oxysporum.the phylogenetic relationships of different species of Fusarium were studied by using the two genes of mitochondrial small subunit and histone H3 in different areas of Shanxi Province.The main results are as follows:SSR information of 7 chromosomes genome was analyzed by bioinformatics methods.A total of 860 SSRs was detected by using SSRIT and Excel,every chromosome include 122 SSRs,the average distance between SSRs was 44.2kb and 18bp was the shortest length.In addition,435 types of motifs were found and the dominant motif types and proportion are different in their repeats.The dominant motif types were tetranucleotide repeat and pentanucleotide repeat and the proportion were 23.84%and 32.56%,respectively.The main repeat motifs were ACAA/TTGT and CAAA/TTTG,with the occurrence number 33 and 32,respectively.So,there are rich SSR loci in genome of Fusarium oxysporum and the result could provide SSR markers for the identification of Fusarium oxysporum.The genetic diversity of Fusarium oxysporum strains was analyzed by simple sequence repeats(SSR).The results showed that 11 pairs of SSR primers had good polymorphism among the 60 synthesized primers.A total of 39 bands were amplified with 11 pairs of primers,with an average of 3.6 bands per primer,and the percentage of polymorphism was 90.5%.The genetic similarity of each strain ranged from 0.436 to 0.949,with an average of 0.662.All the strains could be distinguished at 0.95.Conclusion,the SSR loci in Fusarium oxysporum genomes were rich in polymorphism.SSR markers identified in this study would be useful for genetic variation study of Fusarium oxysporum.Two pairs of primers of its mtSSU rDNA and histone H3 gene fragments were used to test.The results showed that the mtSSU rDNA sequence was about 650bp and the Histone H3 sequence of about 490bp could be amplified and the tested strains were respectively located in 5 and 6 groups of the phylogenetic trees.But there were many branches in the phylogenetic tree constructed by Histone H3 gene fragment.The suggesting that the Histone H3 gene sequence was more variable than the mtSSU rDNA gene sequence.The phylogenetic analysis of mtSSU rDNA and Histone H3 sequences could provide the important reference basis for the genus identification of Fusarium spp..Fusarium was constructed on the basis of mtSSU rDNA and histone H3.The results showed that 1201bp mtSSU rDNA + Histone H3 was combined and all the tested strains were divided into 5 groups.Each group was very different.The results of the combined gene could reduce the influence of different gene evolution rates on the phylogenetic tree,and the results were more accurate.