The Genetic Basis of Plant Functional Traits and the Evolution of Plant-Environment Interactions

Abstract

Leaves are the most conspicuous organs of plants, and their form and function are key determinants of plant ecology. Moreover, energy captured by leaves through photosynthetic carbon reduction forms the base of nearly every terrestrial ecosystem. As such, the morphology and physiology of leaves have been a central focus of research on plant ecophysiology, development, and evolution. We review recent research on the genetic basis of leaf structure and nutrient profile, as well as stomatal patterning, as exemplar traits for understanding the evolution of plant functional traits. We discuss available and emerging methods for determining the genetic basis of plant traits and then present a synthetic assessment of the molecular basis of each trait and the extent to which patterns of natural diversity are relevant to ecoevolutionary analysis. Overall, we find that research on these three traits has emerged from different subdisciplines in biology. We have a deep understanding of the developmental genetics of leaf size and stomatal patterning and, to a lesser degree, leaf shape, though research on these has been limited to a small number of plant species. By contrast, there is a deep literature describing natural genetic diversity of leaf nitrogen content due, in part, to the ease of measuring this trait in large genetic mapping populations. The molecular control of leaf phosphorus concentration, on the other hand, has been severely understudied. For all three traits, there are few examples of studies that have empirically linked molecular genetic variation in specific genes with phenotypic diversity observed in natural populations of plants. We conclude by discussing present challenges with synthesizing different traditions in genetics, physiology, development, and evolution and prospects for progress in the coming years.