Tamang Prabin, Neupane Anjan, Mamidi Sujan, Friesen Timothy, Brueggeman Robert
First, second, fourth, and fifth authors: Department of Plant Pathology, North Dakota State University, Fargo, ND 58108-6050; third author: Department of Plant Science, North Dakota State University, Fargo, ND 58108-6050; and fourth author: U.S. Department of Agriculture-Agriculture Research Service, Red River Valley Agricultural Research Center, Cereal Crops Research Unit, Fargo, ND 58102-2765.
Phytopathology. 2015 Apr;105(4):500-8. doi: 10.1094/PHYTO-04-14-0106-R.
Spot form net blotch (SFNB), caused by the necrotrophic fungal pathogen Pyrenophora teres f. maculata, is an important foliar disease of barley in major production regions around the world. Deployment of adequate host resistance is challenging because the virulence of P. teres f. maculata is highly variable and characterized minor-effect resistances are typically ineffective against the diverse pathogen populations. A world barley core collection consisting of 2,062 barley accessions of diverse origin and genotype were phenotyped at the seedling stage with four P. teres f. maculata isolates collected from the United States (FGO), New Zealand (NZKF2), Australia (SG1), and Denmark (DEN 2.6). Of the 2,062 barley accessions phenotyped, 1,480 were genotyped with the Illumina barley iSelect chip and passed the quality controls with 5,954 polymorphic markers used for further association mapping analysis. Genome-wide association mapping was utilized to identify and map resistance loci from the seedling disease response data and the single nucleotide polymorphism (SNP) marker data. The best among six different regression models was identified for each isolate and association analysis was performed separately for each. A total of 138 significant (-log10P value>3.0) marker-trait associations (MTA) were detected. Using a 5 cM cutoff, a total of 10, 8, 13, and 10 quantitative trait loci (QTL) associated with SFNB resistance were identified for the FGO, SG1, NZKF2, and DEN 2.6 isolates, respectively. Loci containing from 1 to 34 MTA were identified on all seven barley chromosomes with one locus at 66 to 69 cM on chromosome 2H common to all four isolates. Six distinct loci were identified by the association mapping (AM) analysis that corresponded to previously characterized SFNB resistance QTL identified by biparental population analysis (QRpt4, QRpt6, Rpt4, Rpt6, Rpt7, and a QTL on 4H that was not given a provisional gene or QTL nomenclature). The 21 putative novel loci identified may represent a broad spectrum of resistance and or susceptibility loci. This is the first comprehensive AM study to characterize SFNB resistance loci underlying broad populations of the barley host and P. teres f. maculata pathogen.
斑点型网斑病（SFNB）由坏死营养型真菌病原体大麦网斑病菌（Pyrenophora teres f. maculata）引起，是全球主要大麦产区大麦重要的叶部病害。由于大麦网斑病菌的毒力高度可变，且已鉴定出的小效应抗性通常对不同的病原菌群体无效，因此利用充分的寄主抗性具有挑战性。对一个由2062份不同来源和基因型的大麦种质组成的全球大麦核心种质库在苗期进行了表型鉴定，使用了从美国（FGO）、新西兰（NZKF2）、澳大利亚（SG1）和丹麦（DEN 2.6）收集的4株大麦网斑病菌分离株。在2062份进行表型鉴定的大麦种质中，1480份用Illumina大麦iSelect芯片进行了基因分型，并通过了质量控制，5954个多态性标记用于进一步的关联图谱分析。利用全基因组关联图谱从苗期病害反应数据和单核苷酸多态性（SNP）标记数据中鉴定和定位抗性位点。针对每个分离株确定了六种不同回归模型中的最佳模型，并分别进行了关联分析。共检测到138个显著（-log10P值>3.0）的标记-性状关联（MTA）。使用5厘摩的阈值，分别为FGO、SG1、NZKF2和DEN 2.6分离株鉴定出10个、8个、13个和10个与斑点型网斑病抗性相关的数量性状位点（QTL）。在所有7条大麦染色体上鉴定出包含1至34个MTA的位点，其中位于2H染色体66至69厘摩处的一个位点在所有4个分离株中都存在。通过关联图谱（AM）分析鉴定出6个不同的位点，这些位点与之前通过双亲群体分析鉴定出的斑点型网斑病抗性QTL（QRpt4、QRpt6、Rpt4、Rpt6、Rpt7以及4H染色体上一个未赋予临时基因或QTL命名的QTL）相对应。鉴定出的21个假定新位点可能代表了广泛的抗性和/或感病性位点。这是首次对大麦寄主和大麦网斑病菌病原体广泛群体中潜在的斑点型网斑病抗性位点进行全面的AM研究。
