APS Homepage

Oral: Disease Management in the Genomics Era


Use of sequencing technologies in controlling downy mildew of lima bean.
T. MHORA (1) (1) University of Delaware, U.S.A.

View Presentation

Lima bean is an important crop for Delaware and is affected by severe downy mildew epidemics caused by the oomycete Phytophthora phaseoli. Implementing integrated pest management (IPM) strategies could result in yield increases, reduced production costs and environmental benefits. Of the six documented races of P. phaseoli (A – F), race F is currently predominant in the mid-Atlantic region creating a need for downy mildew resistant lima bean cultivars. Molecular markers (Kompetitive Allele Specific PCR assays) for detecting race F resistance in lima bean were developed using bulked segregant analysis via genotyping-by-sequencing (GBS). These assays accurately predicted race F resistance in a collection of 256 genetically diverse lima bean accessions (diversity panel). In order to implement resistance gene pyramiding as part of our IPM strategy, the diversity panel is being used to discover different sources of downy mildew resistance. Lima bean lacks a reference genome complicating analysis of GBS data from diverse accessions. To characterize the genetic diversity of the panel using GBS, data from a biparental maize population was used to develop filters and to better understand how data is handled in our custom non-reference bioinformatics pipeline compared to a reference based analysis. Optimized analysis of GBS data from the diversity panel together with disease resistance phenotype data will allow the identification of important loci for downy mildew resistance.