Diversity Of Pathogenic Large-Spored Alternaria From Compositae In China

Compositae plants including almost 240 genra,around 3000 species grow in variable ecological environments with high medical,ornamental and edible values.Recently,unqualified quarantine,unreasonable drug usage and changeable urban environment,in addition with the increasing of planting areaes,the occurrence of diseases on Compositae plants has been more serious.Especially,the diseases of black spot,brown spot and rot spot caused by Alternaria are increasing.Until now,there are almost 300 Alternaria species reported based on morphology worldwide,comprising large-spored Altenraria and small-spored Altenraria.Totally,52 Alternaria species are isolated from Compositae,from which 46 species from abroad and 20 species from China.The Alternaria spp.from Compositae were investigated in China and the large-spored species were systematically studied.The results are as followed:1.Diversity of large-spored Alternaria species from Compositae plants in ChinaDuring 2016-2018,samples(604)from 35 genra of Compositae plants were collected from 28 cities of 18 provinces all over the country.A total of 398 Alternaria strains were obtained.12 species were identified based on morphology and sequence analyses,from which there were 5 known species(A.helianthificiens,A.leucanthemi,A.sonchi,A.tagetica,A.zinniae),3 new records(A.argyranthemi,A.calendulae,A.cinerariae)and 4 new species(A.coreopsis,A.anhuiensis,A.neimengguensis and A.nanningensis).2.Phylogenetic relationships of Alternaria species from Compositae plants in ChinaPhylogenetic analyses on the basis of six genes(ITS,gpd,TEF1,RPB2,Alt-a1 and ATPase)indicated that large-spored Alternaria species from Compositae plants in China were belong to five clades(Porri,Sonchi,Teretispora,two monotypic lineages).Among them,7 species were belonging to sect.Porri.In addition,most of the species could be identified accurately by a single gene sequence.However,the classification of some species should be based on a combined of multiple loci,ex.A.neimengguensis sp.nov.and A.tillandsiae.3.Dieases on Compositae plants caused by large-spored Alternaria speciesNine new dieases were found according to the pathogenicity tests: leaf blight on Cosmos bipinnatus caused by A.helianthificiens;leaf spot on Zinnia elegans caused by A.zinniae;leaf blight on Kalimeris indica caused by A.leucanthemi;leaf spot on Gynura divaricate,Senecio cineraria,Pericallis hybrida caused by A.cinerariae and on Chrysanthemum coronarium caused by A.argyranthemi;leaf spot onCalendula officinalis caused by A.calendulae;leaf spot on Cosmos sulphureus;leaf spot on Coreopsis drummondii caused by A.coreopsis and A.anhuiensis.In the present study,there were 4 new species,3 new records,and 9 new diseases were found and described associated with large-spored Alternaria from Compositae plants in China after sample collection,strain isolation,pathogenicity tests,morphological examination and phylogenetic analyses.The large-spored Alternaria were systematically studied firstly.The results enrich the diversity of Alternaria from Compositae plants in China and will lay a foundation for the identification,diagnosis and the causal disease controle.