Verticillium transcription activator of adhesion Vta2 suppresses microsclerotia formation and is required for systemic infection of plant roots

Abstract

SummarySix transcription regulatory genes of the Verticillium plant pathogen, which reprogrammed nonadherent budding yeasts for adhesion, were isolated by a genetic screen to identify control elements for early plant infection.Verticillium transcription activator of adhesion Vta2 is highly conserved in filamentous fungi but not present in yeasts. The Magnaporthe grisea ortholog conidiation regulator Con7 controls the formation of appressoria which are absent in Verticillium species. Vta2 was analyzed by using genetics, cell biology, transcriptomics, secretome proteomics and plant pathogenicity assays.Nuclear Vta2 activates the expression of the adhesin-encoding yeast flocculin genes FLO1 and FLO11. Vta2 is required for fungal growth of Verticillium where it is a positive regulator of conidiation. Vta2 is mandatory for accurate timing and suppression of microsclerotia as resting structures. Vta2 controls expression of 270 transcripts, including 10 putative genes for adhesins and 57 for secreted proteins. Vta2 controls the level of 125 secreted proteins, including putative adhesins or effector molecules and a secreted catalase-peroxidase. Vta2 is a major regulator of fungal pathogenesis, and controls host-plant root infection and H 2 O 2 detoxification.Verticillium impaired in Vta2 is unable to colonize plants and induce disease symptoms. Vta2 represents an interesting target for controlling the growth and development of these vascular pathogens.

Genomics Spurs Rapid Advances in Our Understanding of the Biology of Vascular Wilt Pathogens in the Genus Verticillium

“…Although mutants can penetrate roots normally, subsequent root colonization is severely impaired and infection progress halted (60). It is not clear what role adhesion may play in pathogenesis, but Vta2 controls the expression of at least 275 genes, including a number of putative adhesins, virulence-associated effectors such as NLP2 and LysM, and, notably, the catalase-peroxidase gene CPX2, the product of which is secreted and needed for H 2 O 2 detoxification (60). Taken together, these results suggest that Vta2 may be responsible for activating fungal responses to host defenses (60).…”

“…A corresponding adhesion control pathway in Verticillium has not yet been described, but Vta2 is clearly required for pathogenicity of strain JR2 on tomato. Although mutants can penetrate roots normally, subsequent root colonization is severely impaired and infection progress halted (60). It is not clear what role adhesion may play in pathogenesis, but Vta2 controls the expression of at least 275 genes, including a number of putative adhesins, virulence-associated effectors such as NLP2 and LysM, and, notably, the catalase-peroxidase gene CPX2, the product of which is secreted and needed for H 2 O 2 detoxification (60).…”

“…Another transcriptional regulator involved in the control of virulence is the V. longisporum zinc finger protein Vta2 (60). This protein is capable of inducing adhesion (flocculation) in nonadherent yeast strains.…”

VdCrz1 is involved in microsclerotia formation and required for full virulence in Verticillium dahliae

“…The MAPK kinase Msb2 and MAPK Hog1 (Wang et al, unpublished data) are important for microsclerotia formation and virulence in V. dahliae. Furthermore, genes encoding transcriptional regulators with important roles in virulence and development have also been characterized in this fungus (Santhanam and Thomma, 2013;Tran et al, 2014).…”

Verticillium wilt caused by Verticillium dahliae in woody plants with emphasis on olive and shade trees

“…It was also confirmed that VDH1, encoding a class II hydrophobin, is involved in the formation of microsclerotia (Klimes et al 2008;Klimes and Dobinson 2006). In addition, many genes have been characterized that are involved in signal transduction pathways and regulation of microsclerotia formation of V. dahliae, such as VMK1, encoding a mitogen-activated protein kinase (Rauyaree et al 2005), VdGARP1, encoding a glutamic acid-rich protein , the G protein β subunit (named as VGB) (Tzima et al 2012), Vta2, encoding a nuclear zinc finger protein, (Tran et al 2014), the MADS-box transcription factor VdMcm1 , the mitogen-activated protein kinase (MAPK) Hog1 , and the MAPK Msb and Pbs2 Tian et al 2016). Unravelling the functional characterizations of these genes provides insight into the genetic control of microsclerotia formation in V. dahliae.…”