Peeling off the secrets of Populus trichocarpa defences

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Plant specialized metabolites (traditionally called secondary metabolites) are compounds whose biosynthesis is restricted to specific lineages and play key roles in ecological interactions. Plants acquire the ability to synthesize new specialized metabolites as a strategy to cope with biotic and abiotic stress when the environment changes. The long-term vision of my research program is to understand this biochemical response by exploring the natural diversity of specialized metabolites, figuring out how new metabolites are synthesized, and ultimately deciphering how they help the plant thrive in a challenging environment. My proposed NSERC research program focuses on waxes and terpenes from the black cottonwood tree (Populus trichocarpa, poplar) as model systems. Among the traits that plants use to deter invaders, the cuticle and the waxes contained within the cuticle constitute the first barrier against a hostile environment. To investigate the role of the cuticular waxes and individual wax components, we will exploit the extensive variation in wax composition and abundance present in a collection of naturally occurring genotypes of P. trichocarpa. We have shown that alkenes, a type of organic compound, are major components of the wax of black cottonwood leaves. Interestingly, despite the many industrial uses of alkenes, the way by which they are produced in plants was completely unknown. My previous work identified the first enzyme involved in the biosynthesis of alkenes. This discovery has opened the doors to the study of a new pathway for the biosynthesis of cuticular waxes. However, there are still several key areas that need to be investigated if we want to harness cuticular wax diversity as a protection mechanism against environmental stress. In the proposed research we will address the following short-term objectives: 1- Identify and characterize the genes involved in regulating and producing alkenes; 2- Investigate the role of cuticular waxes against environmental stresses; and 3- Develop the tools and methods required to study terpenes, another group of defence compounds of the black cottonwood tree. Even though the underlying question driving my research is why plants synthesize specialized metabolites, the knowledge generated has potential applications in crop improvement and industry. By understanding the biosynthesis and ecological role of specialized metabolites we will be able to breed or engineer plants better adapted to specific environments. Moreover, waxes and terpenes have commercial value as pharmaceuticals, pesticides, food additives, and biofuels. This program will require a multi-disciplinary approach that will train highly qualified personnel in genomics, biochemistry, analytical chemistry, plant physiology and biotechnology.