Chavan Suchitra, Smith Shavannor M
Department of Plant Pathology, University of Georgia.
J Vis Exp. 2014 Jan 3(83):e50712. doi: 10.3791/50712.
Maize is a major cereal crop worldwide. However, susceptibility to biotrophic pathogens is the primary constraint to increasing productivity. U. maydis is a biotrophic fungal pathogen and the causal agent of corn smut on maize. This disease is responsible for significant yield losses of approximately $1.0 billion annually in the U.S.(1) Several methods including crop rotation, fungicide application and seed treatments are currently used to control corn smut(2). However, host resistance is the only practical method for managing corn smut. Identification of crop plants including maize, wheat, and rice that are resistant to various biotrophic pathogens has significantly decreased yield losses annually(3-5). Therefore, the use of a pathogen inoculation method that efficiently and reproducibly delivers the pathogen in between the plant leaves, would facilitate the rapid identification of maize lines that are resistant to U. maydis. As, a first step toward indentifying maize lines that are resistant to U. maydis, a needle injection inoculation method and a resistance reaction screening method was utilized to inoculate maize, teosinte, and maize x teosinte introgression lines with a U. maydis strain and to select resistant plants. Maize, teosinte and maize x teosinte introgression lines, consisting of about 700 plants, were planted, inoculated with a strain of U. maydis, and screened for resistance. The inoculation and screening methods successfully identified three teosinte lines resistant to U. maydis. Here a detailed needle injection inoculation and resistance reaction screening protocol for maize, teosinte, and maize x teosinte introgression lines is presented. This study demonstrates that needle injection inoculation is an invaluable tool in agriculture that can efficiently deliver U. maydis in between the plant leaves and has provided plant lines that are resistant to U. maydis that can now be combined and tested in breeding programs for improved disease resistance.
玉米是全球主要的谷类作物。然而，对活体营养型病原体的易感性是提高产量的主要限制因素。玉米黑粉菌是一种活体营养型真菌病原体，也是玉米玉米瘤黑粉病的病原体。在美国，这种病害每年造成约10亿美元的重大产量损失（1）。目前，包括轮作、施用杀菌剂和种子处理在内的几种方法被用于控制玉米瘤黑粉病（2）。然而，寄主抗性是管理玉米瘤黑粉病的唯一实用方法。鉴定包括玉米、小麦和水稻在内的对各种活体营养型病原体具有抗性的作物，已显著减少了每年的产量损失（3 - 5）。因此，使用一种能够在植物叶片之间高效且可重复地接种病原体的方法，将有助于快速鉴定对玉米黑粉菌具有抗性的玉米品系。作为鉴定对玉米黑粉菌具有抗性的玉米品系的第一步，采用针注接种法和抗性反应筛选法，用玉米黑粉菌菌株接种玉米、大刍草以及玉米×大刍草渐渗系，并筛选抗性植株。种植了约700株由玉米、大刍草以及玉米×大刍草渐渗系组成的植株，用一株玉米黑粉菌进行接种，并筛选抗性。接种和筛选方法成功鉴定出三个对玉米黑粉菌具有抗性的大刍草品系。本文介绍了一种针对玉米、大刍草以及玉米×大刍草渐渗系的详细针注接种和抗性反应筛选方案。本研究表明，针注接种是农业中一种非常有价值的工具，它能够在植物叶片之间高效接种玉米黑粉菌，并提供了对玉米黑粉菌具有抗性的植株品系，这些品系现在可以在育种计划中进行组合和测试，以提高抗病性。
