Collaborative Research: Honeysuckle phylogenomics and the evolution of organ fusion (Lonicera, Caprifoliaceae)

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Plant structures such as flowers and fruits often develop through the fusion of component parts. For instance, the bell-shaped flower of a morning glory is the result of the fusion of five petals, while a pineapple results from the fusion of the developing fruits of multiple individual flowers. Despite organ fusion being important for generating diversity in plants, the process is understudied in many plant groups. This project aims to understand the evolution and genetic regulation of fusion using honeysuckles (genus Lonicera) as a model. Found mostly in the Northern Hemisphere, honeysuckles include approximately 180 species, many of which exhibit different types of fusion within their flowers and fruits. Fusion can be observed across pairs of leaves, between small leaf-like structures associated with the flowers, or among adjacent fruits. This project will reconstruct the evolutionary history of honeysuckles to determine how many times -- and precisely how -- fusion has occurred during the evolution of the group. Researchers will then investigate the genes that control fusion in multiple species within the group. This project will provide the first comprehensive evolutionary and genetic analysis of multiple fusion events within a group of flowering plants. The project will greatly enhance genomic resources for a widely cultivated group of plants, which also includes honeyberry (Lonicera caerulea), a crop plant grown for the high antioxidant content of its fruit. Fifteen undergraduates, a post-doctoral researcher and a graduate student will be trained in diverse laboratory analyses and gain experience working in a field setting. The botanical images produced from this research will form the foundation for developing an art exhibit, Plant Communication and the Art of Fusion, which will be displayed in the Art Gallery at The College of New Jersey and at the Arnold Arboretum of Harvard University.The proposed research combines phylogenomic, morphological, and evolutionary-developmental approaches to test hypotheses on the evolution of fusion in Lonicera and the genes that help regulate organ fusion. The researchers will reconstruct a robust phylogeny for at least 130 of the 180 species of Lonicera using a target-enrichment next-generation sequencing strategy. Researchers will then document and reconstruct the evolutionary patterns of leaf, bracteole, and ovary fusion throughout Lonicera, with an emphasis on ontogenetic changes in a set of 22 focal species. Fused structures will be imaged and quantified to determine the extent of fusion in each species. Finally, this project will examine the phylogenetic history and expression of NAM-like fusion genes across Lonicera to identify correlations between changes in morphology and changes in gene expression.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.