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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Disease and Pest Management Research Unit » Research » Publications at this Location » Publication #385673
Research Project: Integrated Disease Management of Exotic and Emerging Plant Diseases of Horticultural Crops

Location: Horticultural Crops Disease and Pest Management Research Unit

Title: Genomic biosurveillance detects a sexual hybrid in the sudden oak death pathogen

Author
item HAMELIN, RICHARD - University Of British Columbia
item BILODEAU, G J - Canadian Food Inspection Agency
item HEINZELMANN, R - University Of British Columbia
item HRYWKIW, K - University Of British Columbia
item CAPRON, A - University Of British Columbia
item DORT, E - University Of British Columbia
item DALE, AL - Fpinnovations
item GIROUX, E - Canadian Food Inspection Agency
item KUS, STACEY - Fpinnovations
item CARLESON, N C - Oregon State University
item Grunwald, Niklaus - Nik
item FEAU, N - University Of British Columbia

Submitted to: Communications Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/21/2022
Publication Date: 5/19/2022
Citation: Hamelin, R.C., Bilodeau, G., Heinzelmann, R., Hrywkiw, K., Capron, A., Dort, E., Dale, A., Giroux, E., Kus, S., Carleson, N., Grunwald, N.J., Feau, N. 2022. Genomic biosurveillance detects a sexual hybrid in the sudden oak death pathogen. Communications Biology. 5. Article 477. https://doi.org/10.1038/s42003-022-03394-w.
DOI: https://doi.org/10.1038/s42003-022-03394-w

Interpretive Summary: Invasive exotic pathogens pose a threat to trees and forest ecosystems worldwide, hampering the provision of essential ecosystem services such as carbon sequestration and water purification. Phytophthora ramorum, an emergent pathogen that causes sudden oak and sudden larch death, spreads as reproductively isolated, divergent clonal lineages. Recombination has never been reported among these lineages under natural conditions. Here we report the discovery of novel variants of P. ramorum sampled in nurseries that are the result of sexual recombination between clonal lineages NA2 (mating type 2) and EU1 (mating type 1). We show that these hybrids can infect plants and reproduce. We also sequenced the genomes of the hybrids and found that hybridization predicts genome-wide genetic changes, including genes that are known to be involved in host infection. We propose increased genomic biosurveillance in areas where multiple lineages of opposite mating types co-occur given the first incidence of sexual reproduction in the field.

Technical Abstract: Invasive exotic pathogens pose a threat to trees and forest ecosystems worldwide, hampering the provision of essential ecosystem services such as carbon sequestration and water purification. Phytophthora ramorum, an emergent pathogen that causes the sudden oak and sudden larch death, spreads as reproductively isolated divergent clonal lineages. Recombination has never been reported among these lineages under natural conditions and laboratory crosses have yielded unfit progenies. Here we report the discovery of novel variants of P. ramorum that are the result of meiotic hybridization between clonal lineages NA2 (mating type 2) and EU1 (mating type 1). We show that these hybrids can infect plants and produce spores. We sequenced the genomes of the hybrids and found that hybridization predicts functional impact by generating novel genotypic combinations at more than 50,000 loci, including genes such as effectors, carbohydrate-active enzymes and proteases, that are known to be involved in host infection. We also observed post-meiotic, mitotic recombination that could generate additional genotypic and phenotypic variation. We propose increased genomic biosurveillance in areas where multiple lineages of opposite mating types co-occur given the first incidence of sexual reproduction in the field.