CAREER: Temporal and Transgenerational Genomic and Epigenetic Effects of Hybridization in Long-generation Tree Species

Northern Arizona University, Flagstaff AZ

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Warming temperatures and more severe and frequent heat events will bring significant challenges to the development and survival of commercial plant species. Therefore, a deep understanding of the phenotypic plastic responses and drought tolerance is crucial for species management. In long-generation tree species, such as Douglas fir, the management decisions taken today will affect the productivity of forests over the next 50-100 years. The outcomes of this research will be the first of their kind for a conifer species and will significantly contribute to our understanding of the genomic and epigenomic basis of phenotypic variation in long-generation tree species. The role of hybridization in adaptation to changing climates in Douglas fir and other conifers has been poorly studied, so this study will also make important contributions to that area. Undergraduate and graduate students will be trained in molecular lab techniques, greenhouse work and bioinformatic analyses through internships, course modules and summer workshops. Informal science education will be encouraged through science expositions at K-12 schools and public scientific events. Understanding the genomic and epigenomic basis of phenotypic variation is a key biological question. Environmental stresses and hybridization may produce wide genomic and epigenomic changes that can be transmitted to subsequent generations and may contribute to the ability of plants to persist in variable environments. This project will investigate the contribution of hybridization to temporal and inheritable genomic and epigenomic changes that could lead to increased growth and drought tolerance in two varieties of the economically important timber species Douglas fir (DF, Pseudotsuga menziessii var. glauca and var.menziessii). Warming temperatures and more frequent heat events will reduce the growth capacity of the commercial DF coastal variety which is less drought tolerant. In contrast, the DF interior variety is more drought-tolerant, but grows slowly, and is therefore not ideal for commercial purposes. Preliminary studies suggest hybrids between varieties show increased drought tolerance than its parents, which could be due to transgressive segregation or adaptive introgression. This study combines physiological studies, genomic, epigenomic and expression data of pure varieties, F1s, F2s and advanced-generation hybrids in the species, allowing the study of transgenerational effects of hybridization in the genome and epigenome, and the dissection of the molecular basis of heterosis and transgressive segregation. Simultaneous with these research efforts, this project aims to train one postdoctoral fellow, and 31 undergraduate and graduate students. Project outcomes including data and educational resources will be made publicly accessible through project/lab websites as well as through TreeGenes and other long-term public data repositories. 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.