Wei Bohan, Moscou Matthew J, Sato Kazuhiro, Gourlie Ryan, Strelkov Stephen, Aboukhaddour Reem
Cereal Pathology Lab, Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB, Canada.
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada.
Front Plant Sci. 2020 Feb 28;11:158. doi: 10.3389/fpls.2020.00158. eCollection 2020.
The fungus () causes tan spot, a destructive foliar disease of wheat worldwide. The pathogen produces several necrotrophic effectors, which induce necrosis or chlorosis on susceptible wheat lines. Multiple races of have been identified, based on their ability to produce one or more of these effectors. has a wide host range of cereal and non-cereal grasses, but is known to cause damage only on wheat. Previously, we showed that can interact specifically with cultivated barley ( ssp. ), and that the necrotrophic effector Ptr ToxB induces mild chlorosis in a highly selective manner when infiltrated into certain barley genotypes. In the present study, a barley doubled-haploid (DH) population was evaluated for reaction to race 5, a Ptr ToxB-producer. Then a comprehensive genetic map composed of 381 single nucleotide polymorphism (SNP) markers was used to map the locus conditioning this chlorosis. The F1 seedlings, and 92 DH lines derived from a cross between the resistant Japanese malting barley cultivar Haruna Nijo and the susceptible wild barley ( vulgare ssp. ) OUH602 were inoculated with a conidial suspension of race 5 isolate at the two-leaf stage. The seedlings were monitored daily for symptoms and assessed for chlorosis development on the second leaf, 6 days after inoculation. All tested F1 seedlings exhibited chlorosis symptoms similar to the susceptible parent, and the DH lines segregated 1:1 for susceptible:resistant phenotypes, indicating the involvement of a single locus. Marker-trait linkage analysis based on interval mapping identified a single locus on the distal region of the short arm of chromosome 2H. We designate this locus to 1 (). The region encompassing this locus has 99 high confidence gene models, including membrane receptor-like kinases (RLKs), intracellular nucleotide-binding, leucine-rich repeat receptors (NLRs), and ankyrin-repeat proteins (ANKs). This shows the involvement of a dominant locus conferring susceptibility to in barley. Further work using high-resolution mapping and transgenic complementation will be required to identify the underlying gene.
真菌（）引起小麦黄斑病，这是一种在全球范围内对小麦具有破坏性的叶部病害。该病原菌产生多种坏死营养型效应子，可在感病小麦品系上诱导坏死或褪绿。根据其产生一种或多种这些效应子的能力，已鉴定出多个小种。具有广泛的谷类和非谷类禾本科寄主范围，但已知仅对小麦造成损害。此前，我们表明可与栽培大麦（ssp.）特异性相互作用，并且坏死营养型效应子Ptr ToxB在渗入某些大麦基因型时以高度选择性的方式诱导轻度褪绿。在本研究中，对一个大麦双单倍体（DH）群体进行了对小种5（一种产生Ptr ToxB的小种）反应的评估。然后，使用由381个单核苷酸多态性（SNP）标记组成的综合遗传图谱来定位调控这种褪绿的位点。在两叶期，用小种5分离株的分生孢子悬浮液接种F1幼苗以及由抗性日本制麦大麦品种春那二号与感病野生大麦（vulgare ssp.）OUH602杂交产生的92个DH系。每天监测幼苗的症状，并在接种后6天评估第二片叶上褪绿的发展情况。所有测试的F1幼苗均表现出与感病亲本相似的褪绿症状，并且DH系在感病：抗病表型上以1:1分离，表明涉及单个位点。基于区间作图的标记-性状连锁分析在2H染色体短臂的远端区域鉴定出一个单一位点。我们将该位点命名为对1（）。包含该位点的区域有99个高可信度基因模型，包括膜受体样激酶（RLK）、细胞内核苷酸结合富含亮氨酸重复受体（NLR）和锚蛋白重复蛋白（ANK）。这表明在大麦中存在一个赋予对易感性的显性位点。需要进一步开展高分辨率作图和转基因互补研究以鉴定潜在基因。
