Genetic Diversity Of Fusarium Spp. Based On Multiple Gene Fragments And ISSR Markers

Mango malformation disease (MMD) is an important disease of mango that caused by Fusariumspp.. Up to now there had confirmed multiple pathogenic species. This study used four genes, i.e., partial sequences of translation elongation factor (28s rDNA) gene,18s rDNA, ITS and HISTONE, to study the genetic diversity of 47 Fusarium spp. strains collected from three provinces (Yunnan, Guangxi and Hainan).A total of 41 F. mangiferae isolates were confirmed based on the alignment of four gene sequences. The results of the phylogenetic relationship showed that the tree of ITS clustered into five clades and the tree of Histone gene clustered into six clades. The 28s rDNA and 18s rDNA genes are relatively conservative, but the tree of the combination of the two genes showed that four clades formed from 39 isolates. The analysis of the combined four genes showed that the isolates clustered into six clades. The isolates of the clade â…¢ remained highly consistent in each analysis. Almost all of the isolates in clade â…¢ were collected from Huaping country (Yunnan) and Nanning city (Guangxi), and all the isolated were collected from the trees with severe mango malformation disease. The isolates in clade â…  and clade â…¡ appeared differentiation and revealed abundant genetic diversity among the isolates. The isolates from Hainan province distributed the different branches, which indicated that high degree of genetic diversity occurred within the species F. mangiferae in Hainan.There were five primers screened by ISSR molecular marker. A total of 62 bands were produced,59 of which were polymorphic bands (95.16%). Obviously, the genetic variation was found in the UPGMA clustering tree. When the level of similarity coefficient was 0.688, 42 isolates clustered into nine clades. The isolates of clade â…¢ were consistent with the result of gene sequences analyses. The clade should represent the high pathogenic taxa of mango malformation, and it speculated that theisolates of clade might be alien invasive species. The F. mangiferae isolates from Hainan province remained a highly variation degree in the ISSR analysis. The study also found the specific fragments of the high pathogenic taxa though the ISSR analysis. The specific primers for the high pathogenic taxa were attempted to design. Although the specific primers were not obtained successfully, it provided the theoretical foundation for the further research.