2006 NSERC Steacie Fellow Joerg Bohlmann

Giving a tree’s bark more bite

Touch your finger to the sticky resin on a coniferous tree’s bark, and you could well be tapping into a conversation about how to deal with insect pests or disease. Joerg Bohlmann and his research group have begun to translate this biochemical language of conifer-insect interactions, listening in on exchanges of information that might be crucial to developing innovative, science-based solutions for Canadian forests to prevent the devastating effects of forest insect pests such as the mountain pine beetle.

The University of British Columbia researcher has spent the last five years studying the molecular defences that coniferous trees mount against such threats. This response often takes the form of terpenoids, the hydrocarbon and resin acid compounds that are part of the essential oils produced by many plants, including the resin secreted by coniferous trees.

When beetles attempt to lay eggs producing larvae that will eventually undermine the life-sustaining integrity of conifer bark, for example, a tree’s secretions can begin to include volatile compounds that act as repellents for the beetles, as attractants for the beetles’ natural enemies, or as precursors for bark beetle mass aggregation signals. Dr. Bohlmann has been studying the genes and enzymes leading to these compounds as critical signals in bark beetle attack.

“It’s more than a complicated language,” he explains, pointing out that large woody plants have developed sophisticated chemical defence and communications systems to deal with the many different challenges that could arise during centuries spent in one location. “Coniferous trees can produce hundreds of different forms of these chemicals, and they employ very complex biochemical pathways to get there. This is where our research is going – understanding from a very fundamental point of view the biochemical and molecular genetic mechanisms that control the chemical language of conifer defence, down to the genes that encode it.”

His work has laid the foundations for Canada’s first large-scale initiative dedicated to forestry genomics, Treenomix, and a new Conifer Forest Health genomics program focusing on the defence and resistance of conifers against insect pests. A related undertaking reached a major milestone two years ago, when Dr. Bohlmann and other principal investigators teamed up with U.S. and Swedish counterparts to become the first to unravel the genome of the poplar tree.

On the basis of such success, what began as basic, curiosity-driven activity has grown into an initiative with much broader implications. “The results of our research program can potentially be transformed into enormous economic, social, and environmental value for the long-term sustainability of Canada’s forests,” he says.

As one of six 2006 NSERC Steacie Fellows, he is looking forward to unlocking some of that potential. More specifically, Dr. Bohlmann wants to apply genomic insights that could enable us to control or fend off the attack of insects such as the mountain pine beetle, an infestation now affecting more than 15 million hectares of lodgepole pines in British Columbia and moving into Alberta. Genomics research in conifer forest health can have the same benefits as similar work on infectious diseases affecting humans.

“The ability of government and industry to respond to this current epidemic and future bark beetle epidemics is sharply constrained by our limited understanding of the fundamental genomic processes that control the complex biological interactions of these beetles with their conifer host trees,” he says.

In fact, he adds, the beetles themselves appear to be listening in on the molecular and chemical signals of the trees, selecting those that are not genetically predisposed to offer an effective biochemical defence.

For just this reason, Dr. Bohlmann works closely with entomologists and intends to collaborate with scientists in Vancouver’s world-class Michael Smith Genome Sciences Centre to analyse the genetic makeup of the mountain pine beetle. By isolating those features that allow these insects to determine the weakness of some trees and transmit this information, he expects to point the way to new methods of confronting their spread.

“This strategy is analogous to an approach of disarming an enemy by destroying its communications network before or at the start of an assault. We want to use genomics approaches that are entirely new in forest insect pest control to come up with environmentally safe solutions to treat forest diseases at the source of the problem,” he says.