What has natural variation taught us about plant development, physiology, and adaptation?

Abstract

Nearly 100 genes and functional polymorphisms underlying natural variation in plant development and physiology have been identified. In crop plants, these include genes involved in domestication traits, such as those related to plant architecture, fruit and seed structure and morphology, as well as yield and quality traits improved by subsequent crop breeding. In wild plants, comparable traits have been dissected mainly in Arabidopsis thaliana. In this review, we discuss the major contributions of the analysis of natural variation to our understanding of plant development and physiology, focusing in particular on the timing of germination and flowering, plant growth and morphology, primary metabolism, and mineral accumulation. Overall, functional polymorphisms appear in all types of genes and gene regions, and they may have multiple mutational causes. However, understanding this diversity in relation to adaptation and environmental variation is a challenge for which tools are now available.

Figure 1.

Gene Networks Involved in Natural Variation for Flowering Responses to Vernalization and Photoperiod signals in A. thaliana, Wheat, and Rice. Diagrams do not represent full molecular models of flowering regulation, but they show gene network components and branches known to contribute to the natural intraspecific variation existing in these species. Yellow color represents genes that contribute to the variation in a single species, which do not present known homologous genes contributing to natural variation in other species. Green color depicts homologous genes that contribute to the variation in several species. Blue and purple indicate genes accounting for the variation in one species, which show homologous protein domains with genes contributing to the variation in another species. Given their large functional homology, CO, FT, and AP1 homologs of the three species are included in the three diagrams, with small circles depicting genes that do not contribute to natural variation. See text for further details.