FocVel1 influences asexual production, filamentous growth, biofilm formation, and virulence in Fusarium oxysporum f. sp. cucumerinum

Abstract

Velvet genes play critical roles in the regulation of diverse cellular processes. In current study, we identified the gene FocVel1, a homolog of Fusarium graminearum VelA, in the plant pathogenic fungus F. oxysporum f. sp. cucumerinum. This pathogen causes the destructive disease called cucumber Fusarium wilt (CFW), which severely affects the production and marketing of this vegetable worldwide. Transcript analyses revealed high expression of FocVel1 during conidiophore development. Disruption of the FocVel1 gene led to several phenotypic defects, including reduction in aerial hyphal formation and conidial production. The deletion mutant ΔFocVel1 showed increased resistance to both osmotic stress and cell wall-damaging agents, but increased sensitivity to iprodione and prochloraz fungicides, which may be related to changes in cell wall components. In the process of biofilm formation in vitro, the mutant strain ΔFocVel1 displayed not only a reduction in spore aggregation but also a delay in conidial germination on the polystyrene surface, which may result in defects in biofilm formation. Moreover, pathogenicity assays showed that the mutant ΔFocVel1 exhibited impaired virulence in cucumber seedlings. And the genetic complementation of the mutant with the wild-type FocVel1 gene restored all the defects of the ΔFocVel1. Taken together, the results of this study indicated that FocVel1 played a critical role in the regulation of various cellular processes and pathogenicity in F. oxysporum f. sp. cucumerinum.

Serial passage through resistant and susceptible cucumber cultivars affects the virulence of Fusarium oxysporum f. sp. cucumerinum

“…Some virulence-related genes of F. oxysporum have been shown to impact hyphal proliferation and colonization, for example, the six1 protein, an effector secreted during colonizing, is required for virulence of Fol (Rep, Meijer, Houterman, van der Does, & Cornelissen, 2005). However, only a few genes, including fga1, fga2, and fgb1 encoding G-protein α and β subunits, respectively (Jain et al, 2002(Jain et al, , 2003(Jain et al, , 2005 and FocVel1 encoding a velvet protein (Li et al, 2015), have been identified as involved in Foc infection.…”

Agriculturally important microbial biofilms: Present status and future prospects

“…Rhizosphere colonization by Pantoea agglomerans was influenced by purB gens [330]. Velvet genes (FocVel1) involved in biofilm formation in Fusarium oxysporum f.sp.cucumerinum [331]. Quorum-sensing genes esaI, esaR encoding AHL signal synthase regulates bacterial adhesion and biofilm development [246], while, cps genes governs structural functions for EPS synthesis [139,332] in P. stewartii.…”

“…Velvet genes involved in biofilm formation [331] Pantoea stewartii esaI, esaR Quorum-sensing regulation (AHL signal synthase) governs bacterial adhesion, biofilm development [246] cps Encodes the structural functions for EPS synthesis [139,332] Ralstonia solanacearum pilA Type IV pili for surface adhesion and twitching motility [251] Xanthomonas axonopodis exo or eps EPS biosynthesis and virulence [70] Xanthomonas campestris gumD Codes for a glucosyltransferase involved in pathogenicity [333] Xanthomonas citri subsp. citri gumB, galU, gumD Xanthan production [334,335] hrpM Periplasmic glucan biosynthesis [255] gumB, gumD, galU, hrpM, and sahH Biofilm formation [256] Xylella fastidiosa rpf Product of diffusible signaling factor (DSF) involved in quorum sensing, biofilm formation and transmission of X. fastidiosa from insect to plant [319] hxfA or hxfB Hemagglutinin gene involved in cell-to-cell aggregation, colony formation and biofilm maturation within the xylem vessels [336] VELMOUROUGANE ET AL.…”

Transcriptome analysis reveals ethylene-mediated defense responses to Fusarium oxysporum f. sp. cucumerinum infection in Cucumis sativus L.

“…Foc can survive in soil and seeds for many years or even decades [6]. Hyphae of this pathogen penetrate cucumber roots, then spread to the vascular tissues and occludes the xylem vessels, and also produces a toxin to kill cells, which leads to wilting of the leaves or even the entire plant, until plant death occurs several days or weeks after infection [7,8]. FW is extremely difficult to be controlled and changes in the pathogenicity of Foc have led to the ineffectiveness of certain fungicides [9,10].…”