David Des Marais

Massachusetts Institute of Technology

Physiological and developmental control of resource allocation in grasses

All plants must allocate limited resources to survival, growth, and reproduction. Remarkable variation in relative allocation to these three areas is observed within and between species, and in response to environmental factors. Decisions about allocation represent trade-offs between survivorship risk and subsequent fitness benefits. Here, I present results from a combined developmental, physiological, metabolic and transcriptomic study contrasting four Brachypodium species with varying patterns of resource allocation. Two species, B. distachyon and B. stacei, are short-lived species displaying an annual life history pattern. Two species, B. sylvaticum and B. mexicanum, are long-lived species displaying a perennial life history. We specifically test the hypotheses that these two pairs of species differ in their rates of photosynthetic carbon reduction, in their relative growth rates, in their relative allocation to structural, storage and reproductive tissues, and in their capacity to resorb nitrogen from senescing leaves. Our transcriptomic analysis benefits from a new complete genome sequence of B. mexicanum, which I present here for the first time. We further assess genetic correlations among patterns of allocation, primary metabolism, and growth rate among inbred natural accessions of annual B. distachyon and perennial B. sylvaticum.