A forward genetics approach identifies pathogenicity genes in Fusarium oxysporum f. sp. carthami, a fungus causing vascular wilt disease of safflower

Vascular wilt disease caused by Fusarium oxysporum f. sp. carthami (Foc) is one of the biggest constraints for safflower production in India. Understanding the basis of pathogenicity and molecular dissection of its complex processes is of immense economic importance for the effective management of the wilt disease in safflower. In this study, a forward genetic approach was employed as an unbiased tool to identify the candidate pathogenicity-related genes. Agrobacterium mediated random T-DNA mutagenesis in Foc resulted in the generation of 178 Foc transformants. A hydroponics-based pathogenicity screening of generated mutants led to the identification of 12 avirulent mutants. Genome walking with two of the single insertion mutants revealed T-DNA insertion in the intergenic region of one mutant, while in the other mutant T-DNA was inserted in the coding region of a transcription factor. The genes identified in the present study can be targeted by host-delivered RNAi to generate transgenic safflower lines resistant to Foc.