Identification of Fusarium root rot from Tuberose (Polianthes tuberosa L.) in Dezful region and determination of genetic diversity of dominant species based on RAPD analysis and VCG groups

In this study, Fusarium root rot from Tubers in Dezful (Khuzestan, Iran) were identified and genetic diversity of domnnat species was determined. Root Associated fungi were isolated using common isolation technique in laboratory. Collectively 143 isolates of fungi including 110, 27, and 6 at 4 species of Fusarium oxysporum, F. solani, F.equiseti were recovered and identified respectively. Genetic diversity of the population of F.oxysporum was determined using VCG and RAPD techniques. For VCG method, 45 isolates of fungus were selected randomly. Then nit mutant were generated on MMC and Czapeck media each containing 3% KClO3. Phenotypic classes of nit mutants were determined according of the growth types on basal medium containing one of four nitrogen sources (Nitrate, Nitrate, Hypoxanthine, and Ammonium). From recovered nits, 301, 171, and 45 were nit 1, nit 3 and nit M respectively. Complementation test was conducted among different nit mutant of different isolates in all combinations. Results revealed that all isolates were placed into 4 VCG groups, the largest one containing 28 and the rest containing 10, 3 and 4 isolates respectively. In addition, genetic diversity of theses isolates was studied using thirteen primers. Cluster analysis of RAPD data was done using UPGMA, Single and Complete methods. The best results obtained by UPGMA and dice coefficient, which distinguished six main groups at 61% similarity level. In this grouping, group I, III and VI had 2 members each, group II had 12 members. Ten of that belonging to VCG a and groups IV and V had one member each. No close relation was observed between VCG and RAPD method results. Pathogenicity test that was conducted using selected isolates of different VCGs revealed that all were pathogenic to plant. This research is first report of genetic diversity of F. oxysporum on Tuberose in Iran.