021.doi.org/10.1073/pnas.2110968118 j 1 ofPLANT BIOLOGYhypothesis by displaying that the ubiquitously expressed effector VdAve1 that is secreted by the soil-borne fungal plant pathogen Verticillium dahliae acts as a bactericidal protein that promotes host colonization via the selective manipulation of host microbiomes by suppressing microbial antagonists (17, 18). In addition, we demonstrated that VdAve1 plus a additional antibacterial effector named VdAMP2 are exploited by V dahliae for . microbial competitors in soil and promote virulence of V dahliae . in an indirect manner (18). Collectively, these observations demonstrate that V dahliae dedicates a part of its effector catalog . toward microbiota manipulation. Probably, the V dahliae genome . encodes additional effectors that act in microbiome manipulation. Evidently, bacterial and fungal evolution on land preceded land plant evolution. As a consequence, fungal pathogen effectors involved inside the manipulation of (host-associated) microbial communities might have evolved from ancestors that served in microbial competition in terrestrial niches numerous millions of years ago before land plant evolution. Having said that, evidence for this hypothesis is ACAT2 manufacturer presently lacking. V dahliae is an asexual xylem-dwelling fungus that causes vas. cular wilt illness on numerous plant species (19). The fungus survives within the soil inside the kind of multicellular melanized resting structures, called microsclerotia, that provide protection against (a)biotic stresses and can persist within the soil for a lot of years (20). Microsclerotia represent the key inoculum supply of V dahliae . in nature, and their ERĪ± manufacturer germination is triggered by carbon- and nitrogen-rich exudates from plant roots (21). Following microsclerotia germination, fungal hyphae grow via the soil and rhizosphere toward the roots of host plants. Next, V dahliae col. onizes the root cortex and crosses the endodermis, from which it invades xylem vessels. Once the fungus enters those vessels, it forms conidiospores which can be transported with all the water flow till they get trapped, as an example, by vessel end walls. This triggers germination from the conidiospores followed by penetration of cell walls, hyphal growth, and renewed sporulation, major to systematic colonization on the plant (22). When tissue necrosis commences and plant senescence happens, host immune responses fade and V dahliae enters a saprophytic phase in . which it emerges from the xylem vessels to invade adjacent host tissues, that is accompanied by the production of microsclerotia. Upon littering and decomposition of plant tissues, these microsclerotia are released in to the soil (23).Benefits To determine effectors potentially acting in microbiome manipulation, we not too long ago queried the V. dahliae secretome for structural homologs of known antimicrobial proteins (AMPs), which led to the identification of ten candidates like the functionally characterized VdAMP2 (18). Among the remaining nine candidates, we now identified a smaller cysteine-rich protein of 4.9 kDa, which we name VdAMP3 (Ensembl: VDAG_JR2_ Chr3g05620a). As a 1st step in the characterization of VdAMP3, we assessed its predicted structure. Interestingly, VdAMP3 is predicted to adopt a cysteine-stabilized (CS) fold which is also located in defensin-like proteins (Fig. 1A) (246). CS defensins represent a widespread and well-characterized family members of antimicrobial proteins which might be presumed to share a single ancient origin within the final common
