Jason C. L. Brown, Department of Biological Sciences, University of Toronto Scarborough (UTSC) An animal physiologist’s foray into the scarcely inhabited world of plant aging Despite the fact that my graduate research was focused on mitochondrial metabolism in hibernation and daily torpor in mammals, and despite the fact that, in my teaching-focused role at UTSC, I instruct students in animal physiology and vertebrate endocrinology, when I was tasked with carving out a research niche in which I could supervise undergraduate students, I decided to enter the realm of plant aging, which is seemingly an area of focus for only a handful of researchers around the world. I was inspired to undertake such research after reading a book about life history strategies in plants. The book talked at length about the ecological and evolutionary pressures that favour the annual vs. perennial condition in plants but entirely neglected that physiological adaptations must accompany any changes in life history strategy within plant lineages. To this end, my research program has focused on physiological differences between annual and perennial species, with a particular emphasis on the oxidative theory of aging. To date, we have shown that the leaves of perennials are more resistant to oxidative damage from exogenous H2O2 than those from annuals. We have further shown that perennials have higher antioxidant levels in their seeds, leaves, and roots compared to annuals, and that perennials are able to repair oxidative damage to their chlorophyll faster than annuals. Additionally, we have demonstrated that perennials do not limit their concentration of chlorophyll b, despite its increased susceptibility to oxidative damage, but these plants have altered the amino acid sequence of one of their chlorophyll-binding proteins (CP24), thereby making it more stable and better able to fulfill its role in minimizing photosynthetic ROS production. Recently, we also began investigating several lines of early-flowering flax, expecting that they would be more susceptible to oxidative stress given their shorter lifespan. To the contrary, they exhibited significantly higher catalase levels, which complicates our understanding of plant aging.
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