PHYLOGENETIC AND MORPHOLOGICAL CHARACTERIZATION OF FUSARIUM OXYSPORUM F. SP. CEPAE THE CAUSAL AGENT OF BASAL ROT ON ONION ISOLATED FROM TURKEY

Abstract

Fusarium oxysporum f. sp. cepae (FOC) is a serious pathogen, which causes basal rot on onion. In the present study, a total number of 152 Fusarium strains were isolated from infected onions picked from middle black sea region of Turkey. Based on the mean disease severity (DS %), the virulence of each isolate was recorded as highly virulent (70-100% DS), moderately virulent (20-69% DS), low virulent (10-19% DS). At the morphological characterization all of high virulence Fusarium strains was identified as Fusarium oxysporum which based on structures of microconidia (2.5-15 mu m x2-3 mu m and 0-septate), macroconidia (15-20 mu m x 2.5-3 mu m and 3-septate), chlamydospores and other morphological characters. Phylogenetically characterization of strains used primers ITS1 and ITS4. These primers have been successfully amplified a specific 330-bp PCR product the internal transcribed spacer (ITS1-5.8S-ITS2) region of FOC strains. At the phylogenetic classification of high virulence FOC strains Neighbor-joining method was used. There was very little genetic differences (99% similarity) between strains and reference FOC (HQ658965) NCBI Gen Bank due to environmental conditions. This isolates probably from the same clonal lineage. On the other hand, at the phylogenetic characterization, FOC strains formed major genetic differences with other pathogens on onion. Thus, the results indicate that molecular profiling using ITS is a valid method for phylogenetic characterization of FOC.