The central goal of the proposed research is to examine how prey digestion among distantly-related carnivorous plants has evolved and is regulated. The remarkable capability of carnivorous plants to obtain nutrients from non-soil sources, namely insects, has independently arisen perhaps ten separate times in the flowering plants. The carnivorous habit involves attraction, capture, and digestion of prey, and this project focuses on the latter characteristic while specifically testing whether common plant defense proteins have been repeatedly repurposed for acquisition of essential nutrients. Strength in the research lies in the interdisciplinary approach in which multiple species will be compared to address this question. The research has significant potential to inform plant physiology, including studies of nutrition and functions of plant hormones. Additionally, outcomes of this proposal also have broad implications for understanding plant defense, and may result in the discovery of novel proteins for use in plant disease management and alternative technological applications. The project will enable training of graduate and undergraduate students from diverse and underrepresented backgrounds, and findings will be incorporated into undergraduate and graduate-level courses. Through established collaborations, the project will support public programs for K-12 students and adults aimed at teaching concepts related to biological evolution using charismatic carnivorous plants. The research will examine the extent co-option has played in the functional diversification and regulation of common plant defense proteins, specifically pathogenesis-related (PR) proteins, used in prey digestion among independently-evolved carnivorous plants. Using methods in comparative genomics, and a transcriptomics approach coupled with targeted treatments, the project aims to: (1) determine which digestive-functional genes are expressed within the traps of distantly-related Drosera and Pinguicula species, and if these loci are homologous to PR genes used in plant defense, (2) investigate differential expression and regulation of PR genes with trap-specific expression induced by prey, wound-signaling, and phytohormone cascades, and (3) elucidate the mechanisms by which PR genes have evolved by examining gene birth-death, changes in selection pressures promoting functional divergence, genome structural context, and mechanisms for gene family expansion. The research benefits from new genome assemblies, builds upon preliminary RNA-seq data, and lays the foundation for studies of adaptive genomic architecture across the carnivorous plants. Data resulting from the project will also facilitate future projects devoted to systematics, trait evolution, development, and genome evolution. A study of the genes underlying nutrient acquisition will not only add to an evolutionary understanding of plant carnivory, but will have the potential to transform present understanding of the mechanisms by which the evolutionary dynamics of gene families and gene expression drive phenotypic novelty.
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.
