RNAi induced silencing of pathogenicity genes of Fusarium spp. for vascular wilt management in tomato

The necessity to develop new strategies for the control of Fusarium wilt of tomato signifies the identification of pathogencity genes and ascertaining their role to use them as molecular tools for fungicide development or to develop transgenics. Semi-quantitative gene expression studies have identified two pathogenicity genes, FOW2 and chsV , reported as ZnII)2Cys6-type transcription regulator and class V chitin synthase, respectively, as potential ones for being secreted all the time. The roles of these genes in the pathogenicity of Fusarium oxysporum and F. solani have been established by RNA interference (RNAi)-induced silencing (knockdown). The silencing vector encoding hairpin RNA of each of the gene fragment was constructed in a two-step PCR-based cloning, and introduced into the fungal genomic DNA. Silencing of either of the genes resulted in less virulent fungal phenotypes with altered physiological characteristics like sporulation and growth on solid media and a reduction in mRNA expression. The results therefore demonstrate the applicability of these pathogenicity genes as useful molecular targets for exploitation in Fusarium wilt control in tomato.