encoding a pantothenate transporter protein is required for fungal growth, mycelial penetration and pathogenicity of .

INTRODUCTION

The soil-borne vascular fungus is a phytopathogenic fungus known to attack cotton crop causing Verticillium wilt. In previous study, we identified a pantothenate transporter gene () in which can be induced by root exudates from a susceptible cotton variety.

METHODS

In this study, we generated deletion mutants and complementary strain via homologous recombination by a PEG-mediated transformation method and used for the gene functional characterization.

RESULTS AND DISCUSSION

The deletion mutants displayed reduced colony growth, melanin production, spore yield and germination rate, showed abnormal mycelial branching and decreased ability of mycelial penetration and utilization of nutrients (carbon, amino acids and vitamin), leading to a lower pathogenicity. Comparative transcriptome analysis of wild-type and mutant strain cultivated on sterilized carboxymethyl cellophane membranes found that the amino sugar and nucleotide sugar metabolism pathway, which was related to chitin synthesis and degradation as well as UDP-glucose synthesis, was the most significantly down-regulated pathway in deletion mutant. Chitin and β-1,3-glucan content determination found that the chitin content in deletion mutants was significantly lower, while β-1,3-glucan content was higher than that of wild-type and complementary strains. The ratio change of chitin and β-1,3-glucan content in deletion mutants might lead to abnormal branching of mycelium, resulting in the reduced penetration ability of . The decreased chitin content in mutants impaired the fungal cell wall integrity, leading to their increased sensitivity to external stresses.

CONCLUSION

Together, the results demonstrated that is required for growth, development, resistance to external stresses, mycelial penetration and pathogenicity of .