1 research outputs found
Comparative genomics yields insights into niche adaptation of plant vascular wilt pathogens
The vascular wilt fungi Verticillium dahliae and V. albo-atrum infect over 200 plant species, causing billions of dollars in
annual crop losses. The characteristic wilt symptoms are a result of colonization and proliferation of the pathogens in the
xylem vessels, which undergo fluctuations in osmolarity. To gain insights into the mechanisms that confer the organisms’
pathogenicity and enable them to proliferate in the unique ecological niche of the plant vascular system, we sequenced the
genomes of V. dahliae and V. albo-atrum and compared them to each other, and to the genome of Fusarium oxysporum,
another fungal wilt pathogen. Our analyses identified a set of proteins that are shared among all three wilt pathogens, and
present in few other fungal species. One of these is a homolog of a bacterial glucosyltransferase that synthesizes virulencerelated
osmoregulated periplasmic glucans in bacteria. Pathogenicity tests of the corresponding V. dahliae
glucosyltransferase gene deletion mutants indicate that the gene is required for full virulence in the Australian tobacco
species Nicotiana benthamiana. Compared to other fungi, the two sequenced Verticillium genomes encode more pectindegrading
enzymes and other carbohydrate-active enzymes, suggesting an extraordinary capacity to degrade plant pectin
barricades. The high level of synteny between the two Verticillium assemblies highlighted four flexible genomic islands in V.
dahliae that are enriched for transposable elements, and contain duplicated genes and genes that are important in
signaling/transcriptional regulation and iron/lipid metabolism. Coupled with an enhanced capacity to degrade plant
materials, these genomic islands may contribute to the expanded genetic diversity and virulence of V. dahliae, the primary
causal agent of Verticillium wilts. Significantly, our study reveals insights into the genetic mechanisms of niche adaptation of
fungal wilt pathogens, advances our understanding of the evolution and development of their pathogenesis, and sheds
light on potential avenues for the development of novel disease management strategies to combat destructive wilt
diseases