The velvet protein Vel1 controls initial plant root colonization and conidia formation for xylem distribution in Verticillium wilt

Abstract

The conserved fungal velvet family regulatory proteins link development and secondary metabolite production. The velvet domain for DNA binding and dimerization is similar to the structure of the Rel homology domain of the mammalian NF-κB transcription factor. A comprehensive study addressed the functions of all four homologs of velvet domain encoding genes in the fungal life cycle of the soil-borne plant pathogenic fungus Verticillium dahliae. Genetic, cell biological, proteomic and metabolomic analyses of Vel1, Vel2, Vel3 and Vos1 were combined with plant pathogenicity experiments. Different phases of fungal growth, development and pathogenicity require V. dahliae velvet proteins, including Vel1-Vel2, Vel2-Vos1 and Vel3-Vos1 heterodimers, which are already present during vegetative hyphal growth. The major novel finding of this study is that Vel1 is necessary for initial plant root colonization and together with Vel3 for propagation in planta by conidiation. Vel1 is needed for disease symptom induction in tomato. Vel1, Vel2, and Vel3 control the formation of microsclerotia in senescent plants. Vel1 is the most important among all four V. dahliae velvet proteins with a wide variety of functions during all phases of the fungal life cycle in as well as ex planta.

Secreted Secondary Metabolites Reduce Bacterial Wilt Severity of Tomato in Bacterial–Fungal Co-Infections

“…Whether the difference lies in the ability of the fungus to simply invade the roots, cause wilting symptoms, or induce certain plant defense responses could possibly be delineated by examining coinfections with other fungal wilt pathogens such as Verticillium spp. [37] or different strains of Fusarium oxysporum such as the tomato endophyte F. oxysporum Fo47 [38]. Our study also identifies a role for the antibacterial secondary metabolite bikaverin in bacterial disease suppression (Figure 3) and supports our previous results showing inhibition of R. solanacearum growth by this metabolite [28].…”

Pseudomonas Strains Induce Transcriptional and Morphological Changes and Reduce Root Colonization of Verticillium spp.

“…Regulation of secondary metabolism and development is regulated by the velvet family of transcription factors. The V. dahliae velvet protein Vel1 is required for initial root colonization, transport within the plant by conidiation, control of secondary metabolism as well as resting structure formation for long time survival in the soil ( Höfer et al, 2021 ).…”

The Velvet Protein UvVEA Regulates Conidiation and Chlamydospore Formation in Ustilaginoidea virens

“…The velvet family proteins, a class of fungal transcription factors, comprise a conserved velvet domain with proline residues in the middle of the motif [ 12 ]. In filamentous fungi, members of the velvet protein family are global regulators of a variety of cellular processes, such as fungal development, resting structure formation, and the production of secondary metabolites.…”

“…In contrast, the corresponding veA genes were positive regulators of conidiation, as is the case in Aspergillus parasiticus , Fusarium fujikuroi , and Fusarium verticillioides , and hyphal fragmentation, and as is the case in Acremonium chrysogenum [ 16 , 17 , 18 , 19 ]. Furthermore, VeA proteins have been found to play important roles in virulence in many pathogenic fungi, including Magnaporthe oryzae [ 20 ], Fusarium graminearum [ 21 ], B. cinerea [ 15 ], Fusarium oxysporum [ 22 ], Valsa mali [ 23 ], and Verticillium wilt [ 12 ]. Vel1 is necessary for initial plant root colonization in Verticillium dahliae [ 12 ].…”

“…Furthermore, VeA proteins have been found to play important roles in virulence in many pathogenic fungi, including Magnaporthe oryzae [ 20 ], Fusarium graminearum [ 21 ], B. cinerea [ 15 ], Fusarium oxysporum [ 22 ], Valsa mali [ 23 ], and Verticillium wilt [ 12 ]. Vel1 is necessary for initial plant root colonization in Verticillium dahliae [ 12 ]. Taken together, this evidence suggests important regulatory roles for VeA in diverse aspects of fungal biology.…”