Taxonomy And Phylogeny Of Pseudocercospora In Guangdong

The genus Pseudocercospora Speg.has a worldwide distribution in various climatic province,while it is especially diverse in tropical and subtropical regions and species of this genus are associated with a wide range of host species,which can cause Brown spots,Black spots,Leaf blight and so on,including some economically important plants.The studies of Pseudocercospora in China mainly following “Deighton’ s” proposal,lacking of systematic taxonomy.Therefore,further studies on diversity and phylogeny of Pseudocercospora in China is very necessary.In this study,a total of 303 leaf specimens with angular spots,brown spots,black spots,nercotic spots or yellow and withered leaves were collected from Mountain Danxia,South China Botanical Garden,Baiyun Mountain,Tianluhu Forestry Park,Guangzhou Dongshan Lake and so on in multiple sample points in Guangdong.A total of 62 specimens of diseased leaves with Pseudocercospora fungi were obtained by observing and screening under the stereomicroscope,among which 45 strains of Pseudocercospora were obtained by single spora isolation and propagation.According to the total DNA extraction from the isolated strains and four genomic regions(ITS,tef1-α,ACT,RPB2)were amplified by PCR,the phylogenetic tree of Pseudocercospora was constructed by the Maximum Likelihood(ML)and Bayesian Analysis(Bayesian)method.Through the morphological observation,molecular phylogeny study and host plants,23 taxa of Pseudocercospora from 19 genera belong to 16 host families(Ebenaceae,Rosaceae,Rubiaceae,Athyriaceae,Hamamelidaceae,Gesneriaceae,Styracaceae,Saxifragaceae,Berberidaceae,Caprifoliaceae,Celastraceae,Oleaceae,Ericaceae,Gramineae,Leguminosae and Vitaceae)were identified.Of which,4 known species have been identified,including Pseudocercospora eriobotryae(on living leaves of Eriobotryae japonica),Pseudocercospora nandinea(on living leaves of Nandina domestica),Pseudocercospora osmenthicola(on living leaves of Osmanthus fragrans)and Pseudocercospora rhododendricola(on living leaves of Rhododendron simsii),and other 19 taxa were new species.Meanwhile,detailedly morphological descriptions,photography,plating making and comparison with similar species were provides.In this study,we used the method of polyphasic taxonomy.Based on the results of host species,morphology and polygenic molecular systematics result,the species identification and systematic classification of Pseudocercospora in Guangdong Province were conducted,which further revealed the species diversity of Pseudocercospora in Guangdong.Through contrasting and sorting the four genomic regions(ITS,tef1-α,ACT,RPB2),we found that in terms of the ability to distinguish Pseudocercospora species,from high to low the order is tef1-α>RPB2>ACT>ITS.