The mixed sample obtained from tobacco roots inoculated with Verticillium dahliae wild-type strain or VdUGP mutant strain. Verticillium dahliae; Nicotiana benthamiana

In this study, we characterize a homolog of UGP, named VdUGP, from Verticillium dahliae. Compared with wild-type strain V07DF2 and complementation strains, the VdUGP knocked down mutant 24C9 exhibited sensitivity to cell wall stressors, sodium dodecyl sulfate and high sodium chloride concentration. More than 25% of the conidia of the mutant developed into short and swollen hypha, and formed the hyperbranching and compact colonies. Moreover, the mutant exhibits decreased virulence on cotton and tobacco seedlings. Further investigation found that the germination of the mutant spores was significantly delayed than that of the wild-type strain on the host roots. Compared with the wild-type strain, the RNA-seq analysis revealed that a large number of genes encoding secreted proteins and carbohydrate-active enzymes were significantly down-regulated in the mutant at the early stage of infection. Additionally, the RNA-seq data indicated that the mutation affected many KEGG pathways both in the pathogen and in the inoculated plants during the infection stage. These alterations of the mutant in cultural phenotypes, virulence and the gene expression profiles clearly indicate that VdUGP plays important roles in the fungal cell morphogenesis, stress responses and host infection.