Phylogenetic Analysis Of The Genera Bipolaris And Curvularia In China

The genera Bipolaris Shoemaker and Curvularia Boedijn are important plant pathogenic fungi, which can cause diseases of plants in Gramineae. Molecular phylogenetic studies of the two genera were reported during recent years. According to the multi-genes phylogenetic analysis, some species of Bipolaris were treated as the new combinations of the genus Curvularia and the species of Bipolaris were systematically studied.In this study, 255 strains of Bipolaris and 188 strains of Curvularia in our lab isolated from the specimens in China and preserved in Agricultural Culture Collection of China(ACCC) were used as materials. Ribosomal DNA ITS sequencing and analysis of the strains of the two genera were done. More than 80 strains with rDNA ITS sequence difference were selected to sequencing the GPDH and EF-1α genes, and the phylogenetic reconstructions of concatenated and individual gene trees were performed.The results show that 251 strains of Bipolaris belong to 16 published species, including B. bicolor、B. coffeana、B. cookei、B. heveae、B. heliconiae、B. maydis、B. oryzae、B. peregianensis、B. pluriseptata、B. secalis、B. setariae、B. sorokiniana、B. victoriae、B. yamadae、B. zeae and B. zeicola. Among them, the four species B. coffeana、B. heliconiae、B. pluriseptata and B. secalis are new records in China.Phylogenetic reconstructions of concatenated and individual gene trees indicate that the four strains ACCC 38217, ACCC 38219, ACCC 38221 and ACCC 38224 do not belong to either Bipolaris species. Based on multilocus sequence analysis and morphology, the four strains are assigned to a possible new species of Bipolaris.The morphological characters of the representative strain from each species were described in detail, which were grown on the same condition. In this study, most species of Bipolaris were isolated from different hosts’ species in Gramineae, while B. sorokiniana were found on Gramineae, Asteraceae, Cannabaceae, Linaceae, Leguminosae, Magnoliaceae, Malvaceae, Rosaceae, Solanaceae, Ulmaceae 10 families of plants in China.After analysis of 188 rDNA ITS sequences of Curvularia, 36 strains were selected to study the phylogenetic relationship with multi-locus. The phylogenetic trees show that the strains of Curvularia in this study belong to 19 published species, including Curvularia akaiiensis, C. alcornii, C. bannonii, C. geniculata, C. gladioli, C. hawaiiensis, C. heteropogonicola, C. homomorpha, C. inaequalis, C. intermedia, C. lunata, C. nicotiae, C. nodulosa, C. papendorfii, C. robusta, C. spicifera, C. trifolii, C. tuberculata and C. verruculosa. Among them, two species Curvularia akaiiensis and C. alcornii are first reported in China.The individual and multi-genes combined phylogenetic trees show that 3 groups of strains are phylogenetically distinct from published Curvularia species. Three possible new species are found in Curvularia, in which ACCC 36558 and ACCC 36653 are assigned as Curvualaria sp.1, ACCC 38398, ACCC 38411, ACCC 38423, ACCC 38427, ACCC 38413, ACCC 38482 and ACCC 36353 are assigned as Curvualaria sp.2, while ACCC 36570, ACCC36685, ACCC 38337, ACCC 38399 and ACCC 38318 are assigned as Curvualaria sp.3.Molecular phylogenetic relationship of Bipolaris and Curvularia strains were studied in this study, the results will add the knowledge of the species and diversity of the two genera fungi resources in China, and applied the basis of the further research and utilization of these fungi.