title: Cold-induced responses in annual bluegrass genotypes with differential resistance to pink snow mold (Microdochium nivale).
abstract: Greens-type annual bluegrass (Poa annua L.) is susceptible to winter stresses including subfreezing temperatures and pink snow mold (SM). To better understand the mechanisms of SM resistance in annual bluegrass, four SM-resistant and four SM-sensitive genotypes were incubated at low temperature with Microdochium nivale (Fries) Samuels & Hallett, the causal agent of pink snow mold. We assessed the impact of a 6-week incubation period with SM at 2 °C under high humidity (≥ 98%) on the accumulation of cold-induced metabolites and on freezing tolerance. Incubation of annual bluegrass inoculated with SM lead to a major decrease in concentration of cryoprotective sugars such as sucrose and HDP (high degree of polymerization) fructans. Conversely, major amino acids linked to stress resistance such as glutamine and arginine increased in crowns of annual bluegrass in response to SM inoculation. One of the major differences between resistant and sensitive genotypes was found in the concentration of HDP fructans, which remained higher in SM-resistant genotypes throughout the incubation period. HDP fructans were also more abundant in freeze-tolerant genotypes, reinforcing their positive impact on winter survival of annual bluegrass. The identification of genotypes that are resistant to both SM and freezing shows the possibility of being able to improve both traits concomitantly.
authors.affiliation: Soils and Crops Research and Development Centre, Agriculture and Agri-Food Canada, 2560 Hochelaga Blvd., Québec City, Québec G1V2J3, Canada. annick.bertrand@agr.gc.ca
authors.forename: Annick
authors.initials: A
authors.lastname: Bertrand
authors.forename: Yves
authors.initials: Y
authors.lastname: Castonguay
authors.forename: Aïda
authors.initials: A
authors.lastname: Azaiez
authors.forename: Tom
authors.initials: T
authors.lastname: Hsiang
authors.forename: Julie
authors.initials: J
authors.lastname: Dionne
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D001203:Ascomycota / Q000472:pathogenicity; D002241:Carbohydrates; D003080:Cold Temperature; D005615:Freezing; D005838:Genotype; D010935:Plant Diseases / Q000382:microbiology*; D031785:Poa / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology
chemical_list: D000596:Amino Acids; D002241:Carbohydrates