Flowering also has to end: knowns and unknowns of reproductive arrest in monocarpic plants

All flowering plants adjust their reproductive period for successful reproduction. Flower initiation is controlled by a myriad of intensively studied factors, so it can occur in the most favorable conditions. However, the end of flowering is also a controlled process, required to optimize the size of the offspring and to maximize resource allocation. Reproductive arrest was described and mainly studied in the last century by physiological approaches, but it is much less understood at the genetic or molecular level. In this review, we present an overview of recent progress in this topic, fueled by highly complementary studies that are beginning to provide an integrated view of how the end of flowering is regulated. In this emerging picture, we also highlight key missing aspects that will guide future research and may provide new biotechnological avenues to improve crop yield in annual plants.