Dimensions US-China: Collaborative Research: Allozomes and dioecy in plants as drivers of multi-level biodiversity

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Although most flowering plants (angiosperms) have flowers that combine male and female organs, an estimated seven percent of flowering plant species are dioecious, meaning male and female flowers are on separate plants. All poplars and willows are dioecious and these two genera are the most abundant trees and shrubs in many parts of the United States and China. This research aims to understand the genetic basis for the evolution of unisexual flowers in poplars and willows, how defense and volatile chemical compounds differ between male and female individuals, and how different chemical profiles within these plants affects insect biodiversity. Moreover, poplars and willows are also important components of the timber and biofuels industries, so results from this research may lead to new insights into how growth and yield may be improved in the two genera. The collaboration between United States and Chinese researchers will provide extensive cross-disciplinary and cross-cultural training opportunities for over fifteen graduate students and five postdoctoral scholars, and the data generated from the research will be incorporated into teaching materials for courses to be taught in both Chinese and US institutions. Dozens of undergraduates from diverse backgrounds will be trained in plant genomics and functional ecology through direct contributions to data collection and analysis, or through access to the data for research immersion experiences. Finally, researchers will lead K-12 teacher training workshops targeted at under-represented groups in rural Texas to encourage teaching of the foundational theories of biodiversity.This research will address functional biodiversity with a comprehensive survey of gender dimorphism for defense and volatile chemistry in Populus and Salix, and determine how gender dimorphism influences pollinator attraction, herbivore feeding preferences, and overall arthropod community structure. Genetic aspects of biodiversity will be investigated by population genomic characterization of the allosomes in comparison to autosomes. Researchers will map the chromosomal locations of sex determination regions (SDRs) in a suite of sixteen Salix and Populus species, determine whether these genomic regions contain defense and volatile chemistry loci consistent with their theoretical influence on movement of the SDR, and investigate predicted population genomic patterns of allosome divergence caused by interactions between sexually antagonistic loci with the SDR. The phylogenetic component of this research will place gender dimorphism and allosome evolution in a historical context by developing and integrating robust phylogenies of Populus, Salix, and closely related genera within the Salicaceae in order to understand how many times the SDR has moved during evolution of the family, how the SDR has changed in size and composition, and whether movement of the SDR correlates with barriers to interspecific hybridization.