Plant sexual reproduction during climate change: gene function in natura studied by ecological and evolutionary systems biology

BACKGROUND It is essential to understand and predict the effects of changing environments on plants. This review focuses on the sexual reproduction of plants, as previous studies have suggested that this trait is particularly vulnerable to climate change, and because a number of ecologically and evolutionarily relevant genes have been identified. SCOPE It is proposed that studying gene functions in naturally fluctuating conditions, or gene functions in natura, is important to predict responses to changing environments. First, we discuss flowering time, an extensively studied example of phenotypic plasticity. The quantitative approaches of ecological and evolutionary systems biology have been used to analyse the expression of a key flowering gene, FLC, of Arabidopsis halleri in naturally fluctuating environments. Modelling showed that FLC acts as a quantitative tracer of the temperature over the preceding 6 weeks. The predictions of this model were verified experimentally, confirming its applicability to future climate changes. Second, the evolution of self-compatibility as exemplifying an evolutionary response is discussed. Evolutionary genomic and functional analyses have indicated that A. thaliana became self-compatible via a loss-of-function mutation in the male specificity gene, SCR/SP11. Self-compatibility evolved during glacial-interglacial cycles, suggesting its association with mate limitation during migration. Although the evolution of self-compatibility may confer short-term advantages, it is predicted to increase the risk of extinction in the long term because loss-of-function mutations are virtually irreversible. CONCLUSIONS Recent studies of FLC and SCR have identified gene functions in natura that are unlikely to be found in laboratory experiments. The significance of epigenetic changes and the study of non-model species with next-generation DNA sequencers is also discussed.