Genetic Resistance to Fusiform Rust in Southern Pines and White Pine Blister Rust in White Pines—A Contrasting Tale of Two Rust Pathosystems—Current Status and Future Prospects

Abstract

Damage or mortality from pathogens can reduce productivity of forest plantations, as well as significantly harm natural forest ecosystems. Genetic resistance within the host species is the first line of defense for tree species. Resistance breeding programs for the native fusiform rust and exotic (to North America) white pine blister rust diseases are two of the longest concerted efforts in forest trees, spanning more than 50 years. Advances in developing greater genetic resistance have been made in both pathosystems, but unique challenges and opportunities in each system translate to different approaches. Fusiform rust resistance programs have mainly emphasized complete resistance, while partial resistance plays a prominent role in white pine blister rust resistance programs. Advances in the development of molecular genetic tools now permit investigations in conifers and their associated rust pathogens. Good progress has been made in identifying resistant populations and understanding resistance in these pathosystems, and resistant stock is now being used extensively for reforestation and restoration. These programs represent great success stories brought to fruition by the OPEN ACCESSForests 2014, 5 2051 long-term efforts. However, continued support will be needed to enhance the level and fully realize the potential of durable genetic resistance in these invaluable North American conifer species.

Using direct amplification and next-generation sequencing technology to explore foliar endophyte communities in experimentally inoculated western white pines

“…In the current study, NGS was used to explore the establishment of experimentally inoculated endophyte communities in 60 western white pine (Pinus monticola) seedlings. Western white pines have declined to less than 10% of their natural habitat in the last century, largely due to damage from fungal pathogens such as blister rust (Cronartium ribicola) (Fins et al, 2002), which can cause up to 100% mortality in some populations (Sniezko et al, 2014). Foliar endophytes co-inhabit hosts along with pathogens, such as white pine blister rust, and have ample opportunity to influence disease.…”

Genetic variation in susceptibility to pine wilt disease of maritime pine (Pinus pinaster Aiton) half-sib families

“…In this scenario, management activities to slow the spread of PWD in native forests can only be partially effective. Nevertheless, even in susceptible host species, there are always rare resistant individuals that can form the basis of a resistance breeding program for developing populations of genetically diverse and resistant trees (Sniezko 2006;Sniezko and Koch 2017). Intensive artificial selection programs may be necessary to generate populations with quantitative resistance that can be used to accelerate the recovery of populations, as natural selection of the very low proportion of genotypes with high quantitative resistance may be insufficient to allow the recovery of populations over short time scales (Ennos 2015).…”

“…Intensive artificial selection programs may be necessary to generate populations with quantitative resistance that can be used to accelerate the recovery of populations, as natural selection of the very low proportion of genotypes with high quantitative resistance may be insufficient to allow the recovery of populations over short time scales (Ennos 2015). Several authors indicate that if the goal is to develop sources of resistant material for reforestation, the development of a breeding program should be the research priority (Telford et al 2015;Sniezko and Koch 2017).…”

Regeneration Niche of Whitebark Pine in the Canadian Rocky Mountains: The Basis to Restoring an Endangered Species

“…While most whitebark pine populations in the north aren't under immediate threat of extirpation, white pine blister rust infection rates are increasing (Smith et al, 2013), and proactive measures will be the most effective in reducing future risk. In areas where white pine blister rust is not yet prevalent, increasing natural regeneration may be a proactive means of increasing the likelihood of populations developing natural resistance (Schoettle and Sniezko, 2007), while planting blister rust seedlings will be a likely means of introducing blister rust resistance into declining populations (Sniezko et al, 2014). McCaughey et al (2009) provided an excellent seedling planting guide based largely on research done in the core of whitebark pine range.…”