Phylogenetic studies of soybean pathogen Phoma species by Bayesian analysis53-61Views:109
We carried out phylogenetic study analyzing sequences of genetic markers in the taxonomy of Phoma and Phoma-like fungi. Different species of Phoma and Phoma-like fungi occurring on soybean (Phoma pinodella, Phoma sojicola, Phyllosticta sojicola, Phoma exigua var. exigua) are difficult to identy because of their high morphological and symptomatic similarities.
Twenty-two isolates of nine different Phoma species were obtained from reference culture collections. Seven of them were isolated from soybean, the others were collected from different hosts.
The Phoma isolates were firstly characterised by morphologically, and then we employed a part of the gene responsible for the synthesis of translation elongation factor 1 subunit alpha protein (tef1), ITS region, as well as β-tubulin partial sequences as potential genetic markers to infer
phylogenetic relationships among different Phoma species..Finally, their ITS and tef1 sequences were sequenced and analysed by Bayesian approaches.
According to phylogenetic trees inferred by Bayesian analysis of tef1, ITS and β-tubulin sequences, different Phoma species can be separated proving that these phylogenetic markers are well suited for phylogenetic studies of Phoma species. However, the phylogenetic tree does not support the traditional Phoma sections based on morphological characterization.
Bayesian analyses of the three sequences confirmed that the Phyllosticta sojicola species is clustered with the Phoma exigua var. exigua group and the Phoma sojicola is grouped with Phoma pinodella group. The molecular data provide evidence for reclassification of formerly mentioned soybean pathogens.