TY - JOUR TI - The circadian clock controls temporal and spatial patterns of floral development in sunflower AU - Marshall, Carine M AU - Thompson, Veronica L AU - Creux, Nicky M AU - Harmer, Stacey L A2 - Seo, Pil Joon A2 - Kleine-Vehn, Jürgen A2 - Seo, Pil Joon VL - 12 PY - 2023 DA - 2023/01/13 SP - e80984 C1 - eLife 2023;12:e80984 DO - 10.7554/eLife.80984 UR - https://doi.org/10.7554/eLife.80984 AB - Biological rhythms are ubiquitous. They can be generated by circadian oscillators, which produce daily rhythms in physiology and behavior, as well as by developmental oscillators such as the segmentation clock, which periodically produces modular developmental units. Here, we show that the circadian clock controls the timing of late-stage floret development, or anthesis, in domesticated sunflowers. In these plants, up to thousands of individual florets are tightly packed onto a capitulum disk. While early floret development occurs continuously across capitula to generate iconic spiral phyllotaxy, during anthesis floret development occurs in discrete ring-like pseudowhorls with up to hundreds of florets undergoing simultaneous maturation. We demonstrate circadian regulation of floral organ growth and show that the effects of light on this process are time-of-day dependent. Delays in the phase of floral anthesis delay morning visits by pollinators, while disruption of circadian rhythms in floral organ development causes loss of pseudowhorl formation and large reductions in pollinator visits. We therefore show that the sunflower circadian clock acts in concert with environmental response pathways to tightly synchronize the anthesis of hundreds of florets each day, generating spatial patterns on the developing capitulum disk. This coordinated mass release of floral rewards at predictable times of day likely promotes pollinator visits and plant reproductive success. KW - Helianthus annuus KW - external coincidence model KW - anthesis KW - spiral phyllotaxy KW - rhythms KW - floral organs JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -