While our ancestors were able to promote the development of agriculture through traditional selection methods, Jean Bousquet’s goal is to revolutionize forestry through genomic selection. His approach: to reforest with trees whose genes have passed the test even before they are planted.
By Joël Leblanc
It is the middle of spring, and in Professor Jean Bousquet’s laboratories at Université Laval’s Marchand Pavilion, there is no one around. “Everyone’s out working in the field,” Bousquet says with a smile. “We want to take advantage of the nice weather before everyone goes on vacation.”
The “field” he refers to is Québec’s forests: countless trees, but above all a natural gene pool of unsuspected diversity — until recently. For example, although Balsam firs are found throughout North America, they are not exactly the same everywhere.
The same goes for black spruce, jack pine, and larch. For each species, there are subpopulations adapted to the specific conditions of their habitat.
This diversity is a catalog of traits that the researcher can browse through in order to find the best trees, in terms of growth, seed production, resistance to budworm, tolerance to drought, and so on.
“Each tree is more or less efficient for each of these traits. By selecting the best trees for reforestation in any given area, we end up with more productive forests.”
But until recently, the only way of judging the "performance" of trees and selecting the best ones for the next generation was to let them grow to maturity, which took decades. "Now we can take a shortcut,” says Bousquet, who is the holder of the Canada Research Chair in Forest and Environmental Genomics.
Jean Bousquet’s work, which began in the early 2000s, has gained momentum in recent years as DNA sequencing methods have become speedier and more affordable.
“In the beginning,” he recalls, “we were following the leads opened up by human genetics. Sequencing the genome of a tree was unthinkable: the procedure was not only costly, but unfeasible, since the conifer genome is 6 to 10 times larger than our own.
We started off by focusing on sequencing the genes, which produce the RNA found in cells. But 15 years later, new methods are available to forestry, and two years ago, we published the complete white spruce genome.”
Bousquet is particularly interested in adaptive genes, whose frequencies vary from one population to the next. By closely studying these genes, it is possible to compile lists of trees based on their performance for a given criterion, from best to worst. The most tolerant to lack of water, for example, will be planted in drier areas, while the ones most resistant to budworm can be planted in areas where the next infestation is anticipated.
Each year after the logging companies complete their harvest, 125 million conifers are planted to reforest cut-over sites. Once applied, the genomic approach developed by Jean Bousquet and his partners will ensure that the best trees are planted at different locations, on the basis of climate, water availability, risk of infestation, etc.
The goal is the most optimal forest possible, one that grows quickly and well because it contains the varieties that are most productive and best suited to local conditions. It should come as no surprise that Québec’s Ministry of Forestry, Wildlife and Parks, which is responsible for providing all the trees needed for reforestation, is interested in the project and has supported it from the start.
"Québec is ripe for a revolution in forest resource exploitation,” Bousquet notes.
“While forest companies have to build roads to enable them to go ever farther north to find the resource, there is unused land in southern Quebec, right here in the St. Lawrence Valley, that could be used for forest culture.
With our approach, even soils that are considered poor could be reforested and exploited; you just have to plant the right trees.”
While natural commercial conifers in Québec require 70 to 120 years to grow back following a cut, the silviculture of these trees, as proposed by Jean Bousquet, will allow forest companies to harvest trees after only 30 or 40 years.