The fungal‐specific transcription factor Vdpf influences conidia production, melanized microsclerotia formation and pathogenicity in Verticillium dahliae

Abstract

Verticillium dahliae is a soil-borne, hemibiotrophic phytopathogenic fungus that causes wilting in crop plants. Here, we constructed a random insertional mutant library using Agrobacterium tumefaciens-mediated transformation to study the pathogenicity and regulatory mechanisms of V. dahliae. The fungal-specific transcription factor-encoding gene Vdpf was shown to be associated with vegetative growth and virulence, with the highest transcript expression occurring during conidia formation in the V991 strain. The deletion mutants (ΔVdpf) and insertion mutants (IMΔVdpf) produced fewer conidia than did the wild-type (WT) fungi, which contributed to the reduced virulence. Unlike the WT, the complemented strains and IMΔVdpf, ΔVdpf formed swollen, thick-walled and hyaline mycelium rather than melanized microsclerotia. The ΔVdpf mutants were melanin deficient, with undetectable expression of melanin biosynthesis-related genes (Brn1, Brn2 and Scd1). The melanin deficiency was related to cyclic adenosine monophosphate (cAMP) and the G-protein-coupled signalling pathways in this study. Similar to the WT and complemented strains, the ΔVdpf and IMΔVdpf mutants could also successfully penetrate into cotton and tobacco roots, but displayed reduced virulence because of lower biomass in the plant roots and significantly reduced expression of pathogenicity-related genes in V. dahliae. In conclusion, these results provide insights into the role of Vdpf in melanized microsclerotia formation, conidia production and pathogenicity.

Verticillium dahliae transcription factor VdFTF1 regulates the expression of multiple secreted virulence factors and is required for full virulence in cotton

“…S2D–F). It has been shown previously that Fungal_trans domain‐containing proteins are associated with vegetative growth in vitro in other pathogens (Jonkers et al ., ; Lu et al ., ; Luo et al ., ). Unexpectedly, the colony morphology of the VdFTF1‐ deletion mutants on PDA did not differ from the morphology of the wild‐type strain or the T‐DNA insertion mutant M06D06 on PDA.…”

“…As our understanding of the pathogenicity of V. dahliae increases, it appears that a variety of genes are required for virulence towards host plants, including protein kinases (Rauyaree et al ., ; Tian et al ., ; Tzima et al ., ), TFs (Luo et al ., ; Santhanam et al ., ; Sarmiento‐Villamil et al ., ; Tran et al ., ; Xiong et al ., ), effectors (de Jonge et al ., ; Liu et al ., ; Santhanam et al ., ), enzymes involved in plant cell wall degradation (Chen et al ., ; Liu et al ., ; Maruthachalam et al ., ) and other functional genes (Gao et al ., ; Klimes and Dobinson, ; Li et al ., ; Maruthachalam et al ., ; Santhanam et al ., ; Zhang DD et al ., ; Zhang YL et al ., ). In this study, we identified a new pathogenicity and virulence‐related gene encoding a Fungal_trans domain‐containing TF (Figs and ).…”

“…In V. dahliae , TFs such as VdSge1 also exhibit pleiotropic effects, including the requirement for radial growth, conidial production and pathogenicity (Santhanam and Thomma, ). Vdpf regulates melanized microsclerotia formation, conidial production and pathogenicity (Luo et al ., ), and Vst1 controls melanin biosynthesis, morphogenesis and secondary metabolism (Sarmiento‐Villamil et al ., ). In contrast, the phenotypes of all VdFTF1‐ deletion strains were similar to that of the wild‐type strain during cultivation on PDA medium, and they also exhibited similar conidial morphology and production (Fig.…”

“…The reference genome of V. dahliae strain VdLs.17 is predicted to encode 530 TFs classified into 42 TF families (Klosterman et al ., ; Park et al ., ). Like the TFs in other phytopathogens, V. dahliae TFs, including VdSge1 (Santhanam and Thomma, ), Vta2 (Tran et al ., ), VdCrz1 (Xiong et al ., ), Vdpf (Luo et al ., ) and Vst1 (Sarmiento‐Villamil et al ., ), also play important roles in processes involved in pathogenicity, microsclerotium development and morphological development. In addition, gene activity during V. dahliae pathogenesis is regulated by several important signalling factors (Rauyaree et al ., ; Tian et al ., ; Tzima et al ., ) that positively regulate virulence factors.…”

Host‐induced gene silencing of a regulator of G protein signalling gene (VdRGS1) confers resistance to Verticillium wilt in cotton

“…In addition, TFs, through interaction with other TFs or molecular chaperones, play important roles in the virulence or pathogenicity of V. dahliae (Meshi and Iwabuchi, 1995;Pabo and Sauer, 1992). The fungal-specific TF Zn (II) 2 Cys 6 -type Vdpf plays important roles in melanized microsclerotia formation, conidia production and pathogenicity (Luo et al, 2016). RGSs act as GTPase accelerators that promote GTP hydrolysis by the Ga subunits, thereby inactivating the G protein and rapidly switching off G protein-coupled signalling pathways .…”