Plant surface lipid barriers: biosynthesis, regulation and protective functions

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Plants have specialized lipid-based barriers that play critical roles in controlling water movement, nutrient uptake, and gas exchange. These surface lipids also provide protection against various environmental stresses such as drought and pathogen attack. Plant aerial surfaces are coated with cuticle, which is composed mostly of polymerized lipids (cutin) and associated waxes. Likewise, suberin is a lipid-phenolic heteropolymeric barrier found in the cell walls of various external and internal tissues, including root endodermis and mature periderms (e.g. tuber skins and tree bark). As such, plant cuticles and suberized periderms form the largest biological interfaces on the planet, providing first points of contact with the surrounding, often hostile, environment. The long-term goal of my NSERC Discovery research program is to understand the regulated biosynthesis of plant surface lipid barriers and the mechanisms by which they exert their protective functions. My research group is using a combination of genetic and biochemical approaches to study plant surface lipid production, largely in the model plant Arabidopsis thaliana. Specifically, over the next five years, my research team will: (1) characterize a family of Myb transcription factors that control the regulation of suberin deposition, (2) uncover additional enzymes, transporters or regulators that are important for producing a fully functional suberin barrier, (3) provide insights into the mechanisms by which suberin and its associated waxes protect plants under periods of extreme stress, and (4) assess the potential roles of volatile fatty acids and methylketones produced by surface tissues in protection against insects and pathogens. Our overall goal is to gain fundamental knowledge regarding the synthesis and eco-physiological functions of surface lipid barriers, with the applied aim of providing information and tools for the development of stress tolerant crops. The improvement of crop drought tolerance is particularly attractive considering changing climate conditions are currently limiting agricultural production in large areas of the world, including Canada. Enhancing the natural defences of crops towards pathogens and pests is also an important strategy in our efforts to reduce crop losses to disease. In addition, plant surface lipids are rich in fatty alcohols, alkyl esters and oxygenated fatty acids, which are commercially valuable chemicals. Detailed knowledge of plant surface lipid biosynthesis is critical for harnessing this renewable chemical resource to its full potential, for example through the metabolic engineering of oilseed crops and microbes. Over the next 5 years, this research program will provide advanced training to 9 graduate (5 PhD, 4 MSc) and 20-25 undergraduate students in the areas of lipid biochemistry, genetic dissection, molecular biotechnology, and plant stress physiology.