Involvement of FoVEL1 and FoLAE1 in conidiation, virulence and secondary metabolism of Fusarium oxysporum f. sp. niveum

The velvet protein family plays a key factor in coordinating development and secondary metabolism in many pathogenic fungi. However, no previous research has investigated the function of the velvet protein family in Fusarium oxysporum f. sp. Niveum (FON), which causes a highly destructive disease on watermelon. In this study, ∆fovel1 and ∆folae1 deletion mutants and ∆fovel1-C and ∆folae1-C corresponding complementation mutants of FON were confirmed. Meanwhile, effects of phenotype, biochemistry and virulence of the deletion mutants were protected. Compared with the wild-type strains, the ∆fovel1 and ∆folae1 mutants showed different mycelia phenotype, depressed of conidiation and reduced production of bikaverin and fusaric acid. Moreover, their virulence on watermelon plant roots was significant decreased. In addition, all of these alterations in mutants were restored in corresponding complementation strains. Importantly, yeast two hybrid results indicated an interaction relationship between FoVel1 and FoLae1. The results of this study indicated that FoVEL1 and FoLAE1 play critical roles in secondary metabolisms, conidiation, and virulence in FON. These information will deepen our understanding on the genetic and functional roles of the VEL1 and LAE1 in pathogenic fungi.