Taxonomic And Phylogenetic Studies Of Phyllosticta In Karst Area Of Guizhou

Phyllosticta is an important pathogens of various plants,which can cause diseases such as leaf spot,stem blight and fruit rot.It is also an important kind of resource fungi.In order to accurately grasp the species of fungal species of phyloderma in Karst,Guizhou,and to explore the local resources,that to solve the problems in the classification system of the genus phyloderma,this study has been carried out from the following aspects:1.We totally collected more than 280 plant diseased samples from Maolan,broad water,Chishui and Xingren.26 Phyllosticta isolates were obtained by isolation and purification.2.The phylogenetic relationship was conjectured through the combination of 4 genes,such as the ribosome transcriptional spacer sequence(ITS),the actin gene(ACT),the 3-phosphate glyceraldehyde dehydrogenase gene(GPDH)and the extension factor(TEF),meanwhile their morphological characters,such as conidiomata,conidiogenous cells,conidia,mucoid sheaths and apical appendages were also studied.Based on phylogeny and morphology,these 26 isolates were indentified as 4 species,1 new species Phyllosticta cephalotaxi F.Dong S.P.Wu(MB825503)were identified.3 known species are P.capitalensis Henn.,P.musicola N.F.Wulandari,L.Cai& K.D.Hyde,and P.Euphorbia(P.partricuspidatae).3.Using the method of molecular phylogeny and morphology,the pathogens of virginia creeper leaf spot,camellia blotch and taxus leaf spot was identified.It is clear that P.partricuspidatae N.zhou & L.Cai can cause virginia creeper leaf spot,P.musicola N.(P.musicola N F.Wulandari,L.Cai& K.D.Hyde)can cause the leaf spot of Camellia and P.capitalensis Henn.to cause taxus leaf spot disease,which provides a theoretical basis for the prevention and control of the three diseases.4.The experiment found that among the isolated strains,P.capitalensis Henn.was the dominant species of the genus mycophenium in Karst,Guizhou.The total separation was 21,accounting for 80%.A few strains isolated from the other species of Phyllosticta,2 strains of P.musicola,1 strains of P.Partricuspidatae,2 strains of P.cephalotaxi.5.Through 6 methods to analyze the DNA data set of the backbone data and the isolated strains in this study,it is clear that the base composition of each unit is not biased,but there is a significant difference in the substitution form between some strains and most of the strains,and the significant combinations of these differences account for 12.85% of all combinations of the integrated data sets.The difference between substitutions is consistent between the 4 genes.These strains mainly clustered on one branch,forming a separate branch.All the genes that constitute the data set have a certain number of homotypic traits,but with the most ITS,the experiment proves that the data set has a good phylogenetic signal,and the inference system tree is consistent with the true tree.ITS has strong ability to solve deep branches,and ACT and GPD have certain support ability to Asabu branch,but weaker.In order to solve the problem of low support rate of part branches of the system tree,more genes need to be screened in future research to enhance the analytical ability of the shallow branches of the system tree.