Institute for Plant Protection and Environment, 11000 Belgrade, Serbia.
Institute of Botany, Faculty of Biology, University of Belgrade, 11000 Belgrade, Serbia.
Plant Dis. 2020 May;104(5):1378-1389. doi: 10.1094/PDIS-02-19-0289-RE. Epub 2020 Mar 17.
Leaf spot diseases caused by species have been reported worldwide in plants in the Brassicaceae family. However, there is little information on species causing diseases in horseradish. In the present study, 89 spp. isolates from , sampled from nine districts in Serbia, were characterized based on their morphology, physiology, and molecular markers. Morphological characterization and molecular analyses based on , , , and sequences identified three distinct species associated with the disease: , , and . For all species, growth and sporulation rates at 0, 5, 10, 15, 20, 25, 30, 35, and 40°C showed a quadratic response, with having the widest temperature optimum (20 to 30°C) while had higher optimum temperatures (20 to 25°C) than (15 to 20°C). To gain a better understanding of the pathogenicity of these species, the influence of leaf age, host susceptibility, and ability to infect artificially wounded and nonwounded leaves were tested. The pathogenicity test identified and as the main causal agents of horseradish leaf spot disease. Results indicated that young and intact leaves of horseradish and cabbage were less susceptible to infection and also suggested the potential for cross-infection between these two hosts. Haplotype networks showed haplotype uniformity for , two haplotype groups of , and eight haplotype groups of in Serbia and suggest the possible association of some haplotypes with the geographic area. This study is the first to investigate Alternaria leaf spot disease on in Serbia and is the first record of on horseradish in this country.
已在十字花科植物中报道了在世界各地由 种引起的叶斑病。然而，关于辣根致病的 种知之甚少。在本研究中，从塞尔维亚的九个地区采集的 89 个 spp.分离株基于其形态学、生理学和分子标记进行了特征描述。基于,,, 和 序列的形态特征和分子分析鉴定出与疾病相关的三个不同种：,, 和 。对于所有物种，在 0、5、10、15、20、25、30、35 和 40°C 下的生长和产孢率呈二次响应，其中 具有最宽的温度最佳范围（20 至 30°C），而 （20 至 25°C）的最佳温度高于 （15 至 20°C）。为了更好地了解这些种的致病性，测试了叶龄、宿主易感性以及感染人工受伤和未受伤叶片的能力的影响。致病性测试确定 和 是辣根叶斑病的主要致病因子。结果表明，辣根和白菜的幼叶和完整叶片较不易感染，并且这两种宿主之间可能存在交叉感染的可能性。单倍型网络显示 在塞尔维亚具有单倍型均匀性， 有两个单倍型组， 有八个单倍型组，这表明某些单倍型可能与地理区域有关。本研究首次调查了塞尔维亚的辣根上的交替单胞菌叶斑病，也是该国家首次记录到 侵染辣根。
