Diversity of plant life cycles is generated by dynamic epigenetic regulation in response to vernalization

I developed a genetic–physiological model to investigate the molecular mechanisms regulating annual and perennial life histories, and theoretically explored local adaptation caused by environment-specific selection. The model integrates signal transmission in the vernalization pathway and physiological process regarding growth and resource accumulation. The transition from vegetative to reproductive growth was modeled as the process of accumulating the flowering signal, which is transported from leaves to meristems. The model predicted four distinct flowering behaviors, monocarpic annual/perennial and polycarpic-yearly or -intermittent flowering, depending on the epigenetic regulation of FLOWERING LOCUS C (FLC), a transcription factor that acts as a floral repressor. When FLC transcription was not activated after repression, plants always behaved monocarpically, while only a low activation rate of FLC allowed plants to become polycarpal. When mortality was high, rapid repression of FLC was evolutionarily favored, resulting in a summer annual phenotype. As mortality decreased, the evolutionarily favored phenotype shifted from summer to winter annuals, and further to polycarpic phenotypes in which FLC repression occurred slowly. Analysis of local adaptation demonstrated that sensitivity to low temperature increased from northern to southern habitats. These predictions provide important insights into the evolution of diversity in plant life cycles under rapid climate change.