University of Southern Queensland, Centre for Crop Health, Toowoomba, 4350, QLD, Australia.
Queensland Department of Agriculture & Fisheries, Hermitage Research Facility, Warwick, 4370, QLD, Australia.
Plant Dis. 2018 Apr;102(4):760-763. doi: 10.1094/PDIS-07-17-0980-RE. Epub 2018 Jan 26.
Net blotch, caused by Pyrenophora teres, is a major barley (Hordeum vulgare) leaf disease worldwide. P. teres occurs as two forms-P. teres f. teres, and P. teres f. maculata-inducing net and spot-like symptoms, respectively. An intact-seedling assay, where entire seedlings are inoculated by spraying with a conidial suspension, is frequently used for phenotyping net blotch. However, this presents a biosecurity risk in the glasshouse when nonlocal isolates are being screened. Alternatively, a detached-leaf assay (DLA-droplet method) can be used in which leaf segments laid out in a covered tray are inoculated with droplets of a conidial suspension, confining the inoculum. However, using this method, net and spot form symptoms cannot be distinguished from each other. We have developed an improved DLA (DLA-spray method) in which detached whole leaves are sprayed with the inoculum to produce distinct lesions. We compare the results for the three phenotyping methods above using four isolates from both net and spot forms of the disease to inoculate a standard set of eight barley genotypes. Results indicate that the DLA-spray method is a functional, informative and rapid test that readily differentiates the two forms of the pathogen in a biosecure environment.
网斑病由禾旋孢腔菌（Pyrenophora teres）引起，是一种全球性的大麦（Hordeum vulgare）叶病。禾旋孢腔菌有两种形式-P. teres f. teres 和 P. teres f. maculata-分别引起网斑和斑点状症状。完整幼苗接种测定法，即将整株幼苗通过喷洒孢子悬浮液进行接种，常用于网斑病的表型分析。然而，当筛选非本地分离株时，在温室中这会带来生物安全风险。或者，可以使用离体叶片测定法（DLA-液滴法），其中将叶片段放在有盖的托盘上，并用孢子悬浮液的液滴滴注接种，从而限制接种物。然而，使用这种方法，无法区分网斑和斑点形式的症状。我们已经开发了一种改进的 DLA（DLA-喷雾法），其中将离体的整片叶片用接种物喷雾，以产生明显的病斑。我们使用来自网斑和斑点两种形式疾病的四个分离株，对上述三种表型分析方法进行比较，以接种一组八个大麦基因型。结果表明，DLA-喷雾法是一种功能强大、信息丰富且快速的测试方法，可在生物安全环境中轻松区分病原菌的两种形式。
