Characterization of Fusarium oxysporum f. sp melongenae isolates from Turkey with ISSR markers and DNA sequence analyses

Fusarium oxysporum f. sp. melongenae (Fomg), causal agent of Fusarium wilt of eggplant, is a serious pathogen in open fields and greenhouses. Inter-simple sequence repeat (ISSR) banding profiles, sequence analyses of inter-transcribed-spacer (ITS), translation elongation factor 1-alpha (TEF-1 alpha), and actin (actA) DNA regions were employed in this study to determine genetic diversity and population structure of Fomg isolates obtained from Turkey. For ISSR study, (ACTG)(5), (GACAC)(3), (GACA)(4), (GATA)(4), HVH(TG)(7) and (CA)(8)RG primers were selected from a set of 16. Discriminative ability of the primers revealed with various indices including polymorphic information content (PIC), and mean PIC value was calculated as 0.26. The ISSR data revealed 31 loci belonging to 202 Fomg isolates and 14 of them were found to be polymorphic. The isolates on neighbor joining ISSR tree were grouped into two major clusters which separated Fomg and outgroup isolates. Population structure was investigated based on bayesian modeling and results indicated five subpopulations (K = 5, a dagger K = 205.42). Mean genetic and geographical distances among sampling locations revealed only a weak and insignificant correlation (r = 0.583, P = 0.06). Phylogenetic analyses were carried out with ITS, TEF-1 alpha and actA DNA regions with a selected subset of 30 Fomg, along with one non-host and one outgroup isolates. Since ITS region were not able to provide a meaningful separation, TEF-1 alpha and actA sequences of each organism were concatenated individually to build a dendrogram. The clustering tree successfully separated the Fomg, non-host and outgroup isolates in which all Fomg were located on the same branch, forming a monophyletic group in the dendrogram.