Linking Physiology, Genetics, and Ecology in Predicting Crop Responses to Climate Change.

Current rapid shifts in climate and biogeochemistry are concomitantly shifting the plant attributes most important for plant survival and yield. Can we predict the most crucial plant traits for survival and yield associated with global change? We see two qualitatively distinct kinds of pressures on plants that will determine the most crucial traits. First are shifts in the stoichiometry of resource supply vs. the stoichiometry of resource demand. As atmospheric inputs to ecosystems change, the natural stoichiometry of resource supply changes. We focus on three resources whose supply rate is known to be changing due to human activities: carbon, nitrogen and water. We show that correlations with yield shift from traits associated with carbon assimilation to traits associated with water and nitrogen use across a gradient of CO2 supply rates from pre-industrial to late 21st century. Across a N supply gradient, we use structural equation modeling and QTL analysis on recombinant inbred lines to show how C, N and H2O assimilation are under shifting selection and the major genes associated with them shift across the gradient. Physical stresses also limit yield. As the world warms, thermal stress will become an increasingly important limit to native plant distributions and agricultural productivity. We explore genetic variation in the expression of a heat shock protein, AtHsp101, showing that ecotypes from low latitudes express less Hsp101 than more northern ecotypes. We also show that Hsp101 expression suppresses root growth and alters drought and heat tolerance. We show that natural populations of Arabidopsis differ adaptively in their ability to tolerate heat and drought. The mechanisms of adaptation may provide insight for breeding crops for a changing world.