Advances in taxonomy of genus phoma: polyphyletic nature and role of phenotypic traits and molecular systematics.

Phoma is a highly polyphyletic genus with its unclear species boundaries. The conventional system of identification is functional but it has its limitations. Besides morphological studies, chemotaxonomy, secondary metabolite and protein profiling have been assessed for the classification and identification of these fungi. Molecular datasets have provided a better outlook towards the phylogenetic and evolutionary trends of Phoma. Molecular markers such as ITS-rDNA, tubulin, actin, translation elongation factor have been widely used by the taxonomists to demarcate species. However, outcomes gained up till now represent preliminary step towards the study of Phoma systematics and a combined approach would be beneficial in the understanding of this polyphyletic group members. Lately, on the base of molecular phylogeny of the type species of the seven Phoma sections a new teleomorph family, Didymellaceae has been established, besides the Phaeosphaeriaceae related to sect. Paraphoma anamorphs, and the Leptosphaeriaceae to sect. Heterospora anamorphs. The estimated ratio is about 70 % of the recognized Phoma-like species can be associated with the Didymellaceae ascomycetous family.