Canadian Forest Service Publications
Tree rings provide a new class of phenotypes for genetic associations that foster insights into adaptation of conifers to climate change. 2018. Housset, J.; Nadeau, S.; Depardieu, C.; Duchesne, I.; Lenz, P.; Isabel, N.; Girardin, M.P. New Phytol. 218: 630-645.
Issued by: Laurentian Forestry Centre
Catalog ID: 38959
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Local adaptation in tree species has been documented through a long history of common garden experiments where functional traits (height, bud phenology) are used as proxies for fitness. However, the ability to identify genes or genomic regions related to adaptation to climate requires the evaluation of traits that precisely reflect how and when climate exerts selective constraints.
We combine dendroecology with association genetics to establish a link between genotypes, phenotypes and interannual climatic fluctuations. We illustrate this approach by examining individual tree responses embedded in the annual rings of 233 Pinus strobus trees growing in a common garden experiment representing 38 populations from the majority of its range.
We found that interannual variability in growth was affected by low temperatures during spring and autumn, and by summer heat and drought. Among-population variation in climatic sensitivity was significantly correlated with the mean annual temperature of the provenance, suggesting local adaptation. Genotype–phenotype associations using these new tree-ring phenotypes validated nine candidate genes identified in a previous genetic–environment association study.
Combining dendroecology with association genetics allowed us to assess tree vulnerability to past climate at fine temporal scales and provides avenues for future genomic studies on functional adaptation in forest trees.
Plain Language Summary
In this study, the researchers used an interdisciplinary approach to gain a better understanding of the relationships between the white pine’s genome and its physical characteristics (genotype-phenotype association).
The researchers found that white pine growth is particularly affected by specific extreme weather events such as cold temperatures in the spring and fall, and summer droughts. They then used these climatic sensitivity traits to test genotype-phenotype associations. This approach helped validate candidate genes involved in the local adaptation of the tree species.
By combining the study of growth rings with that of association genetics, the researchers were able to assess tree vulnerability to past climate at fine temporal scales and to provide avenues for future research on the functional adaptation of trees to climate change.