Phylogeny Of Alternaria Spp.from Medicinal Plants In Southwest Of China

The genus Alternaria includes saprobic,endophytic and pathogenic species,which can cause diseases on a wide range of important plants,including cereals,ornamentals,oil crops,vegetables,weeds and medicinal plants.Some species produce potent mycotoxins that are involved in the development of disease in plants and mammals.As spores of Alternaria have significant negative effects on plants and human beings,rapid and correct identification of Alternaria species would be a great addition to mycologists and plant pathologists.In order to get a good understanding of Alternaria diversity in Southwest China,five hundred specimens of medicinal diseased samples were collected from Sichuan,Guizhou,Yunnan and Guangxi provinces.The morphological and phylogenetic studies were used to identify the species,as well as studying the diversity.A total of 68 Alternaria isolates were obtained during 2018-2020.We used seven gene regions for phylogenetic studies,and their amplification rates and parsimony-informative characters are higher than previous studies.The analysis of nucleotide sequences of the ITS region revealed a total of 61 isolates isolated from medicinal plants,followed by LSU(59),SSU(57),GPD(60),Tef1(59),RPB2(53),and At-l-a(61).After morphological studies and phylogenetic analysis with combined SSU,ITS,LSU,GPD,Alt-a-1,RPB2,and Tef1 genes,eight new,three reported,and 20 suspected species were identified.The newly identified species are: A.paraalstroemeriae(GUCC21586.3),A.paraarborescens(GUCC21600.1),A.paratenuissima(GUCC21601.4),A.paraburnsii(GUCC21519.11),A.pseudoarborescens(GUCC21103.2),A.pseudoagaisen(GUCC21126.4),A.disarborescens(GUCC2179.5),and A.pseudoalstroemeriae(GUCC21593.6).Three species,A.arborescens,A.limoniasperae,and A.burnsii,are known species.Furthermore,GUCC21591.3;GUCC21302.4;GUCC21589.5;GUCC21837.2;GUCC21173.2;GUCC21847.1;GUCC21950.1a;GUCC21862.1;GUCC2179.1;GUCC21163.1;GUCC21174.4;GUCC21303.1a;GUCC21588.4;GUCC21930.3;GUCC21871.1a;GUCC21589.1;GUCC21956.2;GUCC21602.3;GUCC21GH.2,and GUCC21TLG1,were determined as suspected new species that need further confirmation.This study detailed the diversity of Alternaria species in the Southwest Region of China and the relationship between these fungi and host plants.The finding of this study will provide important references in disease control and resource application.