Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108, USA.
Department of Plant Pathology, University of Minnesota-Northwest Research and Outreach Center, Crookston, MN 56716, USA.
Mol Plant Pathol. 2018 May;19(5):1047-1060. doi: 10.1111/mpp.12608. Epub 2017 Dec 10.
Puccinia coronata f. sp. avenae (Pca) causes crown rust disease in cultivated and wild oat (Avena spp.). The significant yield losses inflicted by this pathogen make crown rust the most devastating disease in the oat industry. Pca is a basidiomycete fungus with an obligate biotrophic lifestyle, and is classified as a typical macrocyclic and heteroecious fungus. The asexual phase in the life cycle of Pca occurs in oat, whereas the sexual phase takes place primarily in Rhamnus species as the alternative host. Epidemics of crown rust happens in areas with warm temperatures (20-25 °C) and high humidity. Infection by the pathogen leads to plant lodging and shrivelled grain of poor quality. Disease symptoms: Infection of susceptible oat varieties gives rise to orange-yellow round to oblong uredinia (pustules) containing newly formed urediniospores. Pustules vary in size and can be larger than 5 mm in length. Infection occurs primarily on the surfaces of leaves, although occasional symptoms develop in the oat leaf sheaths and/or floral structures, such as awns. Symptoms in resistant oat varieties vary from flecks to small pustules, typically accompanied by chlorotic halos and/or necrosis. The pycnial and aecial stages are mostly present in the leaves of Rhamnus species, but occasionally symptoms can also be observed in petioles, young stems and floral structures. Aecial structures display a characteristic hypertrophy and can differ in size, occasionally reaching more than 5 mm in diameter. Taxonomy: Pca belongs to the kingdom Fungi, phylum Basidiomycota, class Pucciniomycetes, order Pucciniales and family Pucciniaceae. Host range: Puccinia coronata sensu lato can infect 290 species of grass hosts. Pca is prevalent in all oat-growing regions and, compared with other cereal rusts, displays a broad telial host range. The most common grass hosts of Pca include cultivated hexaploid oat (Avena sativa) and wild relatives, such as bluejoint grass, perennial ryegrass and fescue. Alternative hosts include several species of Rhamnus, with R. cathartica (common buckthorn) as the most important alternative host in Europe and North America.
Most crown rust management strategies involve the use of rust-resistant crop varieties and the application of fungicides. The attainment of the durability of resistance against Pca is difficult as it is a highly variable pathogen with a great propensity to overcome the genetic resistance of varieties. Thus, adult plant resistance is often exploited in oat breeding programmes to develop new crown rust-resistant varieties. Useful website: https://www.ars.usda.gov/midwest-area/st-paul-mn/cereal-disease-lab/docs/cereal-rusts/race-surveys/.
角斑壳多胞锈菌（Pca）引起栽培和野生燕麦（Avena spp.）冠锈病。这种病原体造成的显著产量损失使冠锈成为燕麦产业中最具破坏性的疾病。Pca 是一种担子菌真菌，具有专性生物营养生活方式，被归类为典型的大环和异宿主真菌。Pca 生命周期中的无性阶段发生在燕麦上，而有性阶段主要发生在鼠李属植物作为替代宿主。在温暖（20-25°C）和高湿度的地区会发生冠锈病流行。病原体的感染会导致植物倒伏和质量差的干瘪谷物。病害症状：易感燕麦品种的感染会导致橙色-黄色圆形至长圆形的夏孢子堆（脓疱），其中含有新形成的夏孢子。脓疱大小不一，长度可超过 5 毫米。感染主要发生在叶片表面，但偶尔也会在燕麦叶鞘和/或花结构（如芒）上出现症状。抗性燕麦品种的症状从斑点到小脓疱不等，通常伴有黄化晕圈和/或坏死。在鼠李属植物的叶片中主要存在疱状和壳状结构，但偶尔也可以在叶柄、嫩茎和花结构上观察到症状。壳状结构显示出特征性的肥大，大小不同，偶尔直径超过 5 毫米。分类学：Pca 属于真菌界、担子菌门、锈菌纲、锈菌目和锈菌科。寄主范围：角斑壳多胞锈菌广义上可以感染 290 种草本宿主。Pca 普遍存在于所有燕麦种植区，与其他谷物锈病相比，它具有广泛的冬孢子寄主范围。Pca 的最常见的草本科宿主包括栽培六倍体燕麦（Avena sativa）和野生亲缘种，如蓝茎草、多年生黑麦草和羊茅。替代宿主包括几种鼠李属植物，其中欧洲和北美的欧洲鼠李（common buckthorn）是最重要的替代宿主。
大多数冠锈病管理策略包括使用抗锈病作物品种和使用杀菌剂。由于 Pca 是一种高度变异的病原体，极易克服品种的遗传抗性，因此很难实现对其的持久抗性。因此，在燕麦育种计划中通常利用成株抗性来开发新的抗冠锈品种。有用的网站：https://www.ars.usda.gov/midwest-area/st-paul-mn/cereal-disease-lab/docs/cereal-rusts/race-surveys/。
