Post Doctoral Associate Cold Spring Harbor Laboratory Cold Spring Harbor, New York
Body of Abstract: Flowering is an essential developmental transition for plant fitness, and consequently many floral traits are remarkably robust—floral morphology is consistent both within a given individual plant and within species, despite huge diversity in floral form among diverged species. Using a comparative approach, we identified deeply conserved cis-regulatory regions in the floral identity regulatory UFO in Brassicaceae and Solanaceae plant species to use as targets for CRISPR-mediated disruption. We found that deletions of conserved non-coding sequences (CNSs) in the Arabidopsis UFO promoter causes petal number variation in a natively highly canalized trait, with the perturbation of different conserved regions causing both different degrees and directions of decanalization. Perturbation of non-conserved regions has no effect on petal number, suggesting that cis-regulatory sequence conservation is a strong predictor of functionality. Disruption of one CNS in tomato, a species with natively decanalized petal number, caused shifts in petal number towards higher counts, whereas disruption in another CNS caused severe flower and inflorescence development defects, perhaps due to precocious or abolished expression of UFO. To identify the molecular mechanisms underlying these phenotypes, we are harnessing both natural and engineered variation in UFO-interacting genes to sensitize our alleles and uncover potential cryptic variation in petal number revealed by this decanalized state. We are also using transcriptomic and reporter approaches to determine how these mutations affect UFO expression and function. This work yields insight into how conserved non-coding sequences regulate conserved developmental pathways across large evolutionary timescales and provides a strong predictive tool in the arsenal for quantitative trait engineering of flower and fruit formation, developmental programs essential for precision agriculture.