New Phytologist (2021) 230, 327-340

Peter M. Henry, Dominique D.A. Pincot, Bradley N. Jenner, Celia Borrero, Manuel Aviles, Myeong-Hyeon Nam, Lynn Epstein, Steven J. Knapp and Thomas R. Gordon (2021)
Horizontal chromosome transfer and independent evolution drive diversification in Fusarium oxysporum f. sp. fragariae
New Phytologist 230 (1), 327-340
Abstract: - The genes required for host-specific pathogenicity in Fusarium oxysporum can be acquired through horizontal chromosome transfer (HCT). However, it is unknown if HCT commonly contributes to the diversification of pathotypes.
- Using comparative genomics and pathogenicity phenotyping, we explored the role of HCT in the evolution of F. oxysporum f. sp. fragariae, the cause of Fusarium wilt of strawberry, with isolates from four continents.
- We observed two distinct syndromes: one included chlorosis ('yellows-fragariae ') and the other did not ('wilt-fragariae '). All yellows-fragariae isolates carried a predicted pathogenicity chromosome, 'chr^Y-frag', that was horizontally transferred at least four times. chr^Y-frag was associated with virulence on specific cultivars and encoded predicted effectors that were highly upregulated during infection. chr^Y-frag was not present in wilt-fragariae; isolates causing this syndrome evolved pathogenicity independently. All origins of F. oxysporum f. sp. fragariae occurred outside of the host's native range.
- Our data support the conclusion that HCT is widespread in F. oxysporum, but pathogenicity can also evolve independently. The absence of chr^Y-frag in wilt-fragariae suggests that multiple, distinct pathogenicity chromosomes can confer the same host specificity. The wild progenitors of cultivated strawberry (Fragaria × ananassa) did not co-evolve with this pathogen, yet we discovered several sources of genetic resistance.
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Database assignments for author(s): Lynn Epstein, Thomas R. Gordon

Research topic(s) for pests/diseases/weeds:
molecular biology - genes
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Fusarium oxysporum f.sp. fragariae		Japan