Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/30/2013
Publication Date: 6/6/2013
Citation: Jain, S., Weeden, N., Porter, L., Eigenbrode, S., Mcphee, K. 2013. Finding linked markers to En for efficient selection of pea enation Mosaic Virus resistance in pea. Crop Science. 10.2135/cropsci2013.04.0211. Interpretive Summary: Pea enation mosaic virus (PEMV) causes an important disease of cool season food legumes including pea, lentil and chickpea, resulting in significant yield loss (10 to 100%) worldwide. PEMV is spread to cool season legumes via the pea aphid or green peach aphid. Spraying the crop with an insecticide to manage the aphids can be expensive and aphids feeding on insecticide-applied plants can still spread the virus prior to dying. Identifying plants that have genes conferring resistance to PEMV is the most economical and environmentally friendly means to manage PEMV. The present investigation was carried out to identify genetic markers that can be used by pea breeders to identify pea plants that contain the En gene. The En gene confers resistance to PEMV. This research used pea lines developed from crosses between a PEMV-susceptible parent (Radley) and a PEMV-resistant parent (Lifter) to genetically map the location of the En gene. The En gene was found to be located between two genetic markers CNGC and tRNAMet2. The presence of these two genetic markers in a pea line correctly predicted the presence of the En gene 99.4% of the time. Pea breeders can use these markers to rapidly screen through pea lines to find lines that are resistant to PEMV without having to artificially inoculate pea plants in greenhouses or naturally screen pea lines under field conditions to determine which lines are resistant to the virus. Using these markers significantly improves the speed with which a pea breeder can select PEMV-resistant pea lines that also contain other desired agronomic characteristics such as high yields and anti-lodging characteristics.
Technical Abstract: Pea enation mosaic virus (PEMV) causes an important disease of cool season food legumes, resulting in significant yield loss worldwide. The present investigation was carried out to study the inheritance and identify the molecular markers linked with the PEMV resistance gene (En) in field pea (Pisum sativum L.) using an F7-derived mapping population developed from the cross ‘Lifter’ (resistant) / ‘Radley’ (susceptible). Three hundred ninety-three recombinant inbred lines (RILs) were phenotyped for reaction to PEMV in the field under natural inoculation and in the greenhouse using artificial inoculation. The RILs segregated in the expected 1:1 ratio for resistance and susceptibility in the field and greenhouse evaluations. Sequence tagged site (STS) markers were developed through an intron targeted amplified polymorphism approach based on comparative mapping with Medicago truncatula and a targeted region amplified polymorphism (TRAP) approach was also used to enrich the genomic region segregating for the En gene. Our results demonstrate that resistance to PEMV in pea is governed by a single gene, En, located on linkage group III between markers CNGC (2.5 cM) and tRNAMet2 (1.3 cM) with many other closely associated markers. These two markers in combination predict the presence of En with 99.4% accuracy in the Lifter/Radley mapping population and have implications for marker-assisted selection for PEMV resistance in pea improvement breeding programs.