Genomic Approaches to Identify Insect Resistance Genes in Poplar Trees

University Of North Dakota Main Campus, Grand Forks ND

Investigators

Abstract

PI: Steven G. Ralph (University of North Dakota) Co-PIs: Wenhao (David) Dai (North Dakota State University); Matias Kirst (University of Florida (UF) As sedentary organisms, plants cannot avoid or escape biotic (e.g., herbivorous insects and opportunistic pathogens) and abiotic (e.g., drought and extreme temperature) stresses in their local environment. Instead, plants have evolved an enormous diversity of anatomical structures and chemical defenses to protect themselves. In response to attack by feeding insects, plants deploy multiple defense mechanisms that are tightly regulated at the molecular level. One of the most successful approaches to identify genes responsible for variation in a trait of interest is to produce mutants that are then screened for alterations in the traits of interest. In previous studies, several dozen mutant lines in poplar trees (Populus spp.) were identified as resistant to feeding by defoliating insects. In this project, the modified gene in at least 10 of these insect resistant lines will be identified. The roles these genes play in mediating insect resistance will be systematically examined in poplar through both gene knock-down and over-expression studies. Furthermore, mutant plants will be subject to thorough phenotypic characterization that includes evaluation of global changes in gene expression and measurement of insect feeding performance and larval development. It is expected that these studies will provide new insight into the genes and pathways that enhance resistance to feeding insects. Identification of specific insect resistance genes will facilitate breeding of improved tree varieties in the future. This project will be performed by a team of scientists, graduate students and undergraduates from three universities. Students will receive intensive training in genomics, bioinformatics and biotechnology through participation in all aspects of the research. A new computer lab course in genomics will be developed at the University of North Dakota that will introduce undergraduate and graduate students to hands-on training in bioinformatic analysis of microarray data. These invaluable experiences will prepare students for future careers as professional biologists and educators. The long term goals of this project are to elucidate genetic mechanisms underlying insect resistance in perennial plants, and to incorporate this knowledge into existing tree breeding programs for better forest health. A detailed description of the results and protocols derived from this project can be viewed at http://www.und.edu/dept/biology/ralph/ralph.htm. All DNA sequences will be deposited in GenBank and microarray data will be accessible through the Gene Expression Omnibus (GEO; http://www.ncbi.nlm.nih.gov/projects/geo/) and the PopGenIE database (http://www.popgenie.db.umu.se/popgenie/). Biological resources generated in this study will be publicly available upon request.