1a.Objectives (from AD-416):
The objective of the proposed research that will be conducted at the FDWSRU is to utilize high throughput virus-induced gene silencing (VIGS) assays to investigate the role of genes necessary for resistance towards Asian Soybean Rust (ASR).
1b.Approach (from AD-416):
Genes targeted for silencing will be selected based upon information garnered from soybean gene expression studies, resistance gene mapping studies, and soybean orthologs of key defense regulators in Arabidopsis. Using the VIGS vectors these candidate genes will be silenced, or "turned off", in soybean plants that display resistance towards select isolates of ASR. Silenced plants will then be evaluated for a breakdown of resistance by challenging the plants with the pathogen and scoring for the development of disease.
Historically, the capacity to perform high-throughput genetic and molecular analyses of the crop species Glycine max (soybean) has been hindered by the lack of genomic information and tools to assess gene function. The development of a virus-induced gene silencing (VIGS) system for use in soybean coupled with the completed genome sequence has made it possible to functionally analyze genes involved in a wide array of physiological responses, including defense. Rpp2 is a gene that has been shown to provide resistance in soybean to certain isolates of the fungal pathogen that causes the disease known as Asian soybean rust. The VIGS system was used in an effort to dissect the genetic pathways operating under the Rpp2 resistance gene. In this analysis we targeted 140 soybean genes suspected to play a role in the Rpp2 pathway. Eleven of these genes were confirmed to play essential roles in resistance. We have begun characterizing these 11 genes in plants carrying Rpp2, and are also assessing whether these genes are required for resistance in soybean plants that do not carry Rpp2.