| Fusarium was a kind of important plant pathogen,which could induce a variety of plant diseases.With unique climate,and a wide variety of crops in Shanxi Province,the diseases universally exist with various Fusarium species.Due to the polytypism and easy variability of Fusarium,it was considered to be one of the most difficult to identify in all fungal groups.Therefore,screening the appropriate gene sequence for the accurate identification of Fusarium identification had an important theoretical and practical value.DNA barcoding was a technology of using a short and common DNA fragments for species identification.Compared with animals and plants,fungal DNA barcoding technology research progress was relatively slow.As the basic sequence of fungal DNA barcoding,the applicability of ITS sequences in some the genus was not high,the resolution of the related species was low.Therefore,the screening of a DNA barcoding for Fuarium,and analyzed the intra-and inter-specific genetic diversity and the population diversity of Fusarium in Shanxi by it to provide a theoretical and scientific basis for Fusarium taxonomy,phylogenetic analysis,inspection and quarantine,and integrated control of related diseases.The main results were as follows:1.The ITS,EF-1? and ?-tubulin sequences were used as candidate DNA barcode markers to screen the suitable DNA barcoding for Fusarium identification.Based on the analysis of 150 sequences of 50 strains belonging to 23 well-established species,the results showed that,the EF-1?sequences was the most suitable gene sequence as a DNA barcoding of Fusarium.The EF-1?sequence had a relatively good intra-and inter-specific variation,and the average genetic distance between species was 31 times of the average genetic distance between intraspecies.All of the tested species could be distinguished by the constructed NJ tree with a bootstrap proportion.Thus,the EF-1?gene sequences could be used as a DNA barcoding of Fusarium,and the genetic distance of 0.04 was chosen as a threshold for the division of Fusarium.2.In this study,the ITS,EF-a,and ?-tubulin genes were chosen to carry out multi-gene sequence analysis of 15 species of Fusarium,the results showed that,a single gene sequence could not fully reflect the interspecies genetic diversity of Fusarium.With the combined analysis of EF-1? and?-tubulin gene sequences,the bootstrap proportion(100%)of each branches and species resolution(93%)were significantly improved,which accurately reflected its interspecies genetic diversity,except certain differences between the genetic relationship and the traditional taxonomy.3.Based on the analysis of EF-la gene sequence,the genetic variation of 52 strains of F.oxysporum showed that the genetic diversity of the intraspecies was very obvious,but the genetic differentiation was not related to the host and geographical origin.4.The results of phylogenetic analysis based on EF-1? gene sequences and population diversity of Fusarium spp.collected from 28 counties(districts)of Shanxi Provinces showed that the morphological species did not fully comply with phylogenetic species.Among the 27 species of Fusarium,F.oxysporum was the dominant specie.The results of population distribution of Fusarium in different geographical regions in Shanxi province showed that F.oxysporum was the dominant species in Yuncheng,Linfen,Xinzhou,Changzhi,Lvliang,Jinzhong and Taiyuan city;F.lateritium was the dominant species in Shuozhou,,solani in Datong,F.verticillioides in Jincheng and F.incarnatum in Yangquan.The results of the population distribution of Fusarium from different hosts showed that the 15 Fusarium species extracted from Lycopersicon esculentum,13 species from Solanum tuberosum and 12 from Glycine max.In these hosts,F.oxysporum was the dominant species in Lycopersicon esculentum,Cucumis sativus,Citrullus lanatus,Solanum tuberosum,Solanum melongena,Cucurbita pepo and Brassica oleracea.F.verticillioides was the dominant species in Glycine max and Zea mays.F.avenaceum and F.graminearum were the dominant species in Triticum aestivum.The results of a polymorphism index and Jaccard similarity index showed that the population diversity of Fusarium species in different areas of Shanxi province was quite different,and the similarity level was between highly similar and similar medium level. |
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