Canadian Forest Service Publications

Prospects for developing durable resistance in populations of forest trees

Year: 2021

Issued by: Pacific Forestry Centre

Catalog ID: 40637

Language: English

Availability: PDF (request by e-mail)

Mark record


Long-lived tree species face a myriad of biotic and abiotic threats over their lifetime, some of the most serious being the presence of non-native diseases or pests capable of killing greater than 95% of trees that are exposed to them. Fortunately, the genetic diversity in many of the affected species also includes some individuals and populations with genetic resistance. Over the last 50 years, applied resistance programs have been undertaken in a range of tree species in the U.S. and resistant parent trees have been selected, tested in seedling inoculation trials and in field trials, selections placed into seed orchards, and the resulting seed used for reforestation and restoration. Both major gene resistance (MGR) and quantitative resistance (QR) have been documented in these resistance programs. However, for each resistance program the question arises whether the resistance will be durable, permitting the species to be used in managed plantations, urban plantings or in native forest restoration over the long-term. Field plantings to-date indicate that in some cases virulence to MGR can arise relatively quickly and QR appears to offer the best opportunity for durability. Ultimately, more time and plantings will be needed to discern if resistance is durable in affected tree species. Changes in climate may alter dynamics that could influence durability of resistance. However, even in the case of virulence to MGR, the pathogen or pest may not spread throughout the range of plantings, and genetic resistance will likely continue to be an invaluable tool for species affected by diseases and pests.