1a.Objectives (from AD-416):
(1) Identify genes involved in resistance to soybean rust, (2) use the information from the disease resistance studies to provide markers that will be useful to plant breeders for the development of new germplasm with resistance to soybean rust, (3) and to enable collaboration among the nation's premier soybean research scientists with the ultimate goal of improving soybean.
1b.Approach (from AD-416):
The proposed research will be conducted using high throughput virus-induced gene silencing (VIGS) assays to identify genes necessary for resistance towards Asian Soybean Rust (ASR). Genes targeted for silencing will be selected based upon gene mapping data of key soybean resistance genes. 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.
To date, six genes known to provide resistance in soybean against the pathogen that causes the disease known as Asian soybean rust have been identified through germplasm screening studies. This information and gene mapping data has enabled us to design virus-induced gene silencing (VIGS) vectors to target one of these resistance genes, referred to as Rpp1. We previously identified candidate genes that we believe to be Rpp1 using the VIGS technology. However, this phenotype is preliminary and further analysis of the Rpp1 candidate is required to confirm its function. To aid in this approach, we are in the process of constructing and screening a bacterial artificial chromosome (BAC) library using genomic DNA obtained from a soybean accession containing Rpp1. The sequence information obtained from the BAC library sequencing should allow us to design Rpp1 expression constructs for heterologous expression studies.