Variation in cedar leaf blight (Didymascella thujina) resistance of western redcedar (Thuja plicata)

摘要

Western redcedar (Thuja plicata Donn ex D. Don) seedlings from a population study with family structure were planted at four sites across coastal British Columbia. All seedlings at the time of planting were infected with cedar leaf blight (CLB) (Didymascella thujina (E.J. Durand) Maire). CLB severity and tree heights were measured at various ages from 2 to 12years. There were significant site differences in CLB severity with the coastal hypermaritime site showing the most and with the submaritime site showing the least. Population differences in disease severity were evident with British Columbia coastal, low-elevation populations exhibiting the most resistance and with British Columbia high-elevation and California sources showing the least. Population resistance was consistent across all four sites (all r> 0.90, p< 0.001). Coefficients of additive genetic variation in CLB severity at all four sites varied from 13.2% to 20.1% with narrow-sense heritabilities from 0.21 to 0.66. Type B genetic correlations in CLB severity across sites averaged 0.59. Type A genetic correlations between 6 year CLB severity and height at the Jordan River site on western Vanvouver Island and at the site on the Queen Charlotte Islands were-0.96 and-0.86 (p 0,90, p < 0,001). Les coefficients de variation génétique additive pour la sévérité de la maladie variaient de 13,2% à 20,1% et l'héritabilité de 0,21 à 0,66 pour les quatre stations. Les corrélations génétiques de type B pour la sévérité de la maladie atteignaient en moyenne 0,59 pour l'ensemble des stations. Les corrélations génétiques de type A entre la sévérité de la maladie à six ans et la hauteur étaient respectivement de -0,96 et -0,86 (p < 0,001) à JR et QC. La discussion porte sur l'influence du climat et de l'exposition antérieure à la brûlure des aiguilles sur les variations dans et entre les populations dans les populations naturelles de thuya géant ainsi que sur l'impact pour la gestion des ressources génétiques.