Taxonomy Of Related Fungal Genera Causing Sooty Blotch And Flyspeck And Their Diversity In China

Sooty blotch and flyspeck (SBFS) is a disease complex that occurs on a wide range ofhosts in warm and humid areas worldwide. SBFS causes cosmetic damage to fruit such asapple and pear due to the smudges formed on the surface, resulting in economic losses to fruitgrowers. The epiphytic SBFS fungal complex is highly diverse, including dozens of species inmore than ten genera. However, most of these SBFS fungal species are putative species andhaven’t been named yet, which has impeded the biology, epidemiology or control studies ofSBFS fungi. Therefore, the aim of this study was to resolve the taxonomy of some SBFSrelated fungal genera by employing both phylogenetic analyses and morphological characters.Then the diversity of SBFS fungal complex in China was analyzed by using phylogeneticanalyses.Base on SBFS fungal strains obtained from apple, pawpaw (Asimina triloba) andCucurbita maxima from China, USA and Turkey, taxonomy of some novel taxa were resolved.A novel genus, Scleroramularia, was established in Dothideomycetes. Scleroramularia couldnot be assigned in order level yet and probably represented an undescribed order inDothideomycetes. Pseudoveronaea was a novel genus introduced in Dissoconiaceae,Capnodiales. Besides, Uwebraunia, a former synonym of Dissoconium, was resurrected inDissoconiaceae in this study. Uwebraunia and Dissoconium were shown to be differentgenera from both morphological comparisons and phylogenetic analyses.Dissoconium became a monophyletic genus after the resurrection of Uwebraunia andincluded three species: D. aciculare, D. eucalypti and D. proteae. Uwebraunia was comprisedof four novel combinations, U. australiensis, U. commune, U. dekkeri and U. musae.Uwebraunia was first reported to cause SBFS.Twenty-one novel species and one novel combination were delineated in generaMicrocyclospora, Microcyclosporella, Pseudoveronaea, Ramichloridium, Scleroramularia,and Zasmidium. Novel species included Microcyclospora liquanensis, Microcyclosporellacylindrica, Microcyclosporella lingbaoensis, Microcyclosporella obclavata,Microcyclosporella tianensis, Microcyclosporella yanchangensis, Pseudoveronaea ellipsoidea, P. obclavata, Ramichloridium binensis, R. cucurbitae, R. liquanensis, R. luensis, R. luteum, R.punctatum, R. zhengensis, Scleroramularia abundans, S. asiminae, S. henaniensis, S.pomigena, S. shaanxiensis, Zasmidium angulare. The novel combination was R. mali.Zasmidium were first reported to cause SBFS.A total of323apple SBFS fungal strains and40from other hosts (including hawthorn,pear, persimmon, citrus and crap apple) were obtained from a survey conducted in appleproduction area in China from2005to2007. Based on phylogenetic analyses of363SBFSfungal strains, SBFS fungi in China were shown to be highly diverse. Thirty-five phylogeneticspecies were revealed from357strains, excluding six strains that were uncertain. Of the35phylogenetic species,22have been described and13remain to be resolved.Of the35phylogenetic species,28were occasionally found and only from restrictedaeras, whereas seven were frequently found from different provinces. Seven common speciesincluded Sterile mycelia sp. CN, Peltaster sp. CN, Pseudoveronaea ellipsoidea,Ramichloridium liquensis-like, Ramichloridium luensis-like, Zygophiala wisconsinensis andHoujia yanglingensis. Sterile mycelia sp. CN were found from four different provinces.Peltaster sp. CN and Pseudoveronaea ellipsoidea were obtained from five different provinces,respectively. Each of other four species was found from three different provinces.Number of strains was different among the seven common SBFS fungal phylogeneticspecies. Sterile mycelia sp. CN had122strains, with33.7%of the total strain numbers.Peltaster sp. CN, Pseudoveronaea ellipsoidea and Ramichloridium liquensis-like had55,40and41strains, respectively, occupying15.2%,12.2%and11.3%of the total strain number.Ramichloridium luensis-like, Zygophiala wisconsinensis and Houjia yanglingensis had fewerstrains, with17,6and5strains respectively, that is,4.7%,1.7%and1.4%of the total strainnumber.There were also variations in host range of the35phylogenetic species. Of which,34were isolated from apples, and five species were isolated from apples as well as other hosts.