Matthiesen R L, Abeysekara N S, Ruiz-Rojas J J, Biyashev R M, Maroof M A Saghai, Robertson A E
Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011.
Department of Plant and Soil Sciences, University of Delaware, Newark 19716.
Plant Dis. 2016 Jul;100(7):1424-1428. doi: 10.1094/PDIS-08-15-0916-RE. Epub 2016 Apr 4.
Soybean cultivars with specific single resistance genes (Rps) are grown to reduce yield loss due to Phytophthora stem and root rot caused by the oomycete pathogen Phytophthora sojae. To identify novel Rps loci, soybean lines are often screened several times, each time with an isolate of P. sojae that differs in virulence on various Rps genes. The goal of this study was to determine whether several isolates of P. sojae that differ in virulence on Rps genes could be combined into a single source of inoculum and used to screen soybean lines for novel Rps genes. A set of 14 soybean differential lines, each carrying a specific Rps gene, was inoculated with three isolates of P. sojae, which differed in virulence on 6 to 10 Rps genes, individually or in a 1:1:1 mixture. Inoculum containing the 1:1:1 mixture of isolates was virulent on 13 Rps genes. The mixed-inoculum method was used to screen 1,019 soybean accessions in a blind assay for novel sources of resistance. In all, 17% of Glycine max accessions and 11% of G. soja accessions were resistant (≤30% dead plants), suggesting that these accessions may carry a novel Rps gene or genes. Advantages of combining isolates into a single source of inoculum include reduced cost, ability to screen soybean germplasm with inoculum virulent on all known Rps genes, and ease of identifying novel sources of resistance. This study is a precursor to identifying novel sources of resistance to P. sojae in soybean using RXLR effectors.
种植具有特定单一抗性基因（Rps）的大豆品种，以减少由卵菌病原体大豆疫霉引起的疫霉茎基腐病和根腐病造成的产量损失。为了鉴定新的Rps位点，大豆品系通常要经过多次筛选，每次使用对各种Rps基因毒力不同的大豆疫霉分离株。本研究的目的是确定几种对Rps基因毒力不同的大豆疫霉分离株是否可以组合成单一接种源，并用于筛选大豆品系中的新Rps基因。一组14个大豆鉴别品系，每个品系携带一个特定的Rps基因，分别用三种对6至10个Rps基因毒力不同的大豆疫霉分离株或按1:1:1的比例混合接种。含有1:1:1混合分离株的接种物对13个Rps基因具有毒力。采用混合接种法在盲测中筛选了1019份大豆种质资源以寻找新的抗性来源。总体而言，17%的栽培大豆种质资源和11%的野生大豆种质资源具有抗性（≤30%的植株死亡），这表明这些种质资源可能携带一个或多个新的Rps基因。将分离株组合成单一接种源的优点包括成本降低、能够用对所有已知Rps基因具有毒力的接种物筛选大豆种质资源以及易于鉴定新的抗性来源。本研究是利用RXLR效应子鉴定大豆对大豆疫霉新抗性来源的前奏。
