Comparative genomics reveals the in planta‐secreted Verticillium dahliae Av2 effector protein recognized in tomato plants that carry the V2 resistance locus

Abstract

Plant pathogens secrete effector molecules during host invasion to promote colonization. However, some of these effectors become recognized by host receptors to mount a defence response and establish immunity. Recently, a novel resistance was identified in wild tomato, mediated by the single dominant V2 locus, to control strains of the soil-borne vascular wilt fungus Verticillium dahliae that belong to race 2. With comparative genomics of race 2 strains and resistancebreaking race 3 strains, we identified the avirulence effector that activates V2 resistance, termed Av2. We identified 277 kb of race 2-specific sequence comprising only two genes encoding predicted secreted proteins that are expressed during tomato colonization. Subsequent functional analysis based on genetic complementation into race 3 isolates and targeted deletion from the race 1 isolate JR2 and race 2 isolate TO22 confirmed that one of the two candidates encodes the avirulence effector Av2 that is recognized in V2 tomato plants. Two Av2 allelic variants were identified that encode Av2 variants that differ by a single acid. Thus far, a role in virulence could not be demonstrated for either of the two variants.

Transposable elements contribute to genome dynamics and gene expression variation in the fungal plant pathogenVerticillium dahliae

“…Previous genomic comparisons among a narrow selection of V. dahliae strains have revealed extensive chromosomal rearrangements, which were proposed to have contributed to the establishment of dynamic genomic regions ( de Jonge, et al 2013;Faino, et al 2016). To systematically assess their prevalence and abundance in a considerably larger collection of V. dahliae strains, we used paired-end sequencing reads for de novo prediction of SVs in 42 V. dahliae strains Chavarro-Carrero, et al 2021) together with the gapless genome assembly of strain JR2 as a reference . With a combination of four commonly used SV-callers ( Supplementary Fig.1), 919 high-confidence SVs were identified in total, comprising 410 deletions, 49 inversions, 24 duplications, and 436 translocations ( Figure 1A, Supplementary Fig.1).…”

“…The originally identified LS regions, together with the additional genomic regions that share a similar chromatin profile, are now referred to as dynamic genomic regions . Importantly, these dynamic genomic regions are enriched for in planta induced effector genes that contribute to host colonization (Klosterman, et al 2011;de Jonge, et al 2012;de Jonge, et al 2013;Kombrink, et al 2017;Gibriel, et al 2019;Chavarro-Carrero, et al 2021). Furthermore, these regions are enriched in relatively young and transcriptionally active TEs (Faino, et al 2016;.…”

A single amino acid polymorphism in a conserved effector of the multihost blast fungus pathogen expands host-target binding spectrum

“…Accelerated gene evolution is a hallmark of pathogen adaptation and is often associated with host-range expansions and host-jumps [1,[14][15][16][17][18][19][20][21]. However, despite extensive knowledge about the evolutionary dynamics of pathogen effectors, the molecular and biochemical basis of how they adapt to new host-targets is still largely unknown.…”

“…Despite major advances in understanding how pathogen effectors evade plant immunity, we still know little about how effectors acquire new host targets, especially as the pathogen shifts from one host to another [1,[14][15][16][17][18][19][20][21]. Our study provides a molecular evolution and structural biology framework to study effector adaptation in a multihost pathogen.…”

“…Effector genes are often located in specific genomic regions that allow for rapid evolution, such as gene gain and loss, emergence of adaptive mutations and horizontal gene transfer [11][12][13][14]. In biotrophic filamentous plant pathogens, accelerated gene evolution is mostly documented at the level of coevolution with a single host species, but it has also been associated with host-range expansions and host jumps [1,[14][15][16][17][18][19][20][21]. However, the molecular and biochemical processes associated with adaptive evolution between host-specific lineages of a multihost plant pathogen remain poorly understood.…”