Floral induction in response to environmental cues: extending a century of progress

MAIN CONCLUSION: Great progress has been made in understanding the mechanisms of floral induction based on physiology and molecular genetics, whereas recent research suggests that future developments will come from protein biochemistry, genomics, imaging, and mathematical modeling. During the twentieth century, plant physiologists showed how the developmental transition from vegetative growth to flowering is controlled by environmental cues, such as day length and temperature. They defined a number of interesting questions such as the identity of the signal induced in response to day length in leaves that is translocated to the shoot meristem to induce flowering, and the mechanism by which plants sense and remember exposure to winter temperatures. Application of molecular-genetics approaches from the 1990s identified regulatory proteins and small RNAs that control these responses, first in Arabidopsis and later in several crops. These advances identified a series of new questions. In this Perspective article, I highlight some of these issues and select some recent papers that show how protein biochemistry, genomics, imaging, and mathematical modeling address these questions, and will in turn improve our understanding of the mechanisms of floral induction.