Conservation of flowering pathways in angiosperms opens the window for modeling flowering dynamics based on gene expression patterns to predict the occurrence of flowering events in natural environments. The molecular mechanisms underlying responses to seasonal changes in day length and temperature are well demonstrated for plants and animals, and genetically informed models have been developed to predict future phenology under climate change. However, the proximate cues for flowering in the least seasonal climates are still uncertain.
Here we compared the flowering phenology between temperate and tropical rain forests based on expression analysis of highly conserved flowering-time genes and developed a model that predicts flowering dynamics in tropical rain forests in Southeast Asia. The model that considered the synergistic effect of chilling and drought was successful to explain the observed gene expression dynamics in two Shorea species in peninsular Malaysia. Nonlinear time series analyses of meteorological data revealed that using chilling and drought as a flowering cue is adaptive to synchronize the timing of seedling growth with the period when sufficient moisture is available. Our study emphasizes the usefulness of modeling approach for comprehensive understanding of both proximate and ultimate mechanisms underlying synchronous flowering in tropics.