Genetic diversity of Fusarium solani the causal agent of tomato root and crown rot using VCGs

Seventy nine isolates of Fusarium solani were obtained from crown and root rotted parts of tomato plants collected from different regions of Khuzestan province during autumn 2009 using Nash-Snyder medium. Pathogenicity of isolates was tested on potted tomato seedlings of cultivar Primo at 2-leaf stage, under field conditions. Genetic diversity among F. solani isolates was also studied using vegetative compatibility groups (VCGs). Pathogenicity tests revealed that all the isolates were pathogenic. In order to determine VCGs, nit mutants were generated on culture medium CDAC supplemented with 5% KClO3 and Rose Bengal. Using this medium collectively 631 nit mutants were recovered. Nit mutants were divided into 3 phenotypic classes, nit1 (68%), nit3 (18%) and NitM (14%) according to their growth pattern on basal media containing one of four nitrogen sources: sodium nitrate, sodium nitrite, hypoxantine and ammonium tartrate. Complementation test among nit mutants placed isolates into 25 vegetatively compatible groups. In this investigation no relation was observed between VCGs and geographic regions.