TRMS: High-Throughput Functional Analysis of Soybean Defense Pathways by Virus-Induced Gene Silencing

Iowa State University, Ames IA

Investigators

Abstract

PI: Steven A. Whitham (Iowa State University) CoPI: Thomas Baum (Iowa State University) CoPI: John H. Hill (Iowa State University) CoPI: Melissa G. Mitchum (University of Missouri) Soybean is the second most economically important row crop species in the United States, but very little information is available on the specific genes that regulate soybean defenses. The soybean crop is perennially subjected to attack by a variety of pathogens. Studies involving model plants, such as Arabidopsis, have yielded much information on plant defense genes and have shown that there is general conservation of defense related pathways across species. Knowledge of defense-related genes in model plants combined with the extensive sequence information available to soybean provides the opportunity to transfer research from model systems to soybean. The overall goal of this project is to interrogate the functions of soybean genes in disease resistance pathways. This will be accomplished by incorporating information from soybean gene expression, resistance gene mapping studies, and soybean homologs of key genes that regulate defense responses in Arabidopsis. In each of the three specific objectives of this project, high throughput virus-induced gene silencing (VIGS) assays will be used to investigate the roles of the candidate genes in resistance to the important soybean pathogens Soybean mosaic virus (SMV), Asian soybean rust (ASR), and soybean cyst nematode (SCN). This research will provide key knowledge needed to unravel defense signaling networks of soybean, which is a requirement for modulating plant resistance in the future. In soybean, there is a critical need to develop methods for analyzing the functions of genes on a scale that allows researchers to exploit the available soybean sequence information and knowledge gained from model systems. The implementation of the VIGS assays will demonstrate proof of concept that high-throughput gene function studies are feasible in soybean and can be applied to other important traits. The broader impacts of this project address both scientific and societal needs. It is expected that this research will be exploited to improve soybean cultivars for disease resistance by accelerating breeding programs and by enabling the engineering of novel resistance traits. The investigators will make the vectors, VIGS constructs, and methods developed in this project available to the soybean research community. The soybean sequences inserted into the VIGS constructs will be made available through the Soybase database (http://soybase.agron.iastate.edu/). The participation of 7th-12th grade teachers and undergraduate students in this project is expected to further broaden the impact by encouraging young people with aptitude and interest to pursue careers in the biological sciences. The teachers will participate in the NSF Research Experience for Teachers program that is held each summer for seven weeks at Iowa State University. The teachers receive training in molecular biology techniques, curriculum development, and engage in independent research projects in the investigators? laboratories. The undergraduates will participate directly in the research project throughout the year under the mentorship of graduate students or postdoctoral scientists. Finally, scientific exchange will be enhanced through collaboration with Brazilian scientists interested in applying fundamental research to the problem of ASR.