Construction of a Large Mutational Library from a Defoliating Verticillium dahliae Strain and its Evaluation

Agrobacterium tumefaciens Mediated Transformation (ATMT) was used to establish an insertional mutant library.Firstly, we have developed and optimized ATMT system using defoliation strain of V. dahlia, which is the causal agents of wilt on cotton.Furthermore, a library consisted of 4890 T-DNA insertion mutants were generated.Compared with wild-type strain, 34.7% of mutants significantly reduced their colony growth rates among the 196 mutants that were randomly selected, while 34.8% of mutants increased their colony growth rate, 16.8% of mutants lost their ability to produce microsclerotia, 30.0% of mutants decreased their sporulation ability and 27.1% of mutants reduced their pathogenicity.Especially, mutant VdAG30, VdAG153, VdAG151 and VdAG95 showed significant reduce in pathogenicity.In this study, the constructed ATMT mutant library was found to be effective and suitable for defoliating V. dahliae strain and could lay a foundation for cloning candidate pathogenicity-related genes and development-related genes in V. dahliae in the future.