Ergot, caused by Claviceps purpurea, is a primary disease concern in irrigated cool-season grass seed production systems of Oregon. In order to better understand the genetic diversity, population structure, and the epidemiology of C. purpurea in grasses grown for seed, 226 isolates were obtained using a hierarchical sampling strategy from two fields each of Kentucky bluegrass (n = 102) and perennial ryegrass (n = 124) and characterized using 12 microsatellite markers. A total of 194 unique multilocus genotypes (MLGs) were identified in this study. There were moderate levels of genotypic diversity (H = 3.43 to 4.23) and gene diversity (H_exp = 0.45 to 0.57) within fields. After clone correction, analysis of molecular variance revealed that 66% of the genetic variation occurred between the two C. purpurea isolates collected from the same seed head of individual plants, indicating that many of the seed heads bearing multiple sclerotia were infected by ascospores rather than conidia. However, the majority of the clonal isolates obtained in this study were collected from the same seed head (i.e., the two isolates were identical MLGs), indicating a role of conidia (honeydew) in secondary infections within seed heads. Genetic differentiation was observed between populations from different hosts (22%) but was confounded by geography. The standardized index of association ranged from 0.007 to 0.122 among the four populations, suggesting potential outcrossing and differences in the relative contribution of ascospores and conidia to ergot among the fields. The results from this study provide insights into the epidemiology of ergot in cool-season grass seed crops of Oregon.

俄勒冈州灌溉的凉季草种子生产系统中，由紫癜引起的麦角菌病是引起人们关注的主要疾病。为了更好地了解种草中紫C衣原体的遗传多样性，种群结构和流行病学，采用分层抽样策略从肯塔基州蓝草（n = 102）和多年生黑麦草（n = 102）的两个田地中获得了226个分离株。n = 124），并使用12个微卫星标记进行表征。这项研究共鉴定了194个独特的多基因座基因型（MLG）。有中等水平的基因型多样性（H = 3.43至4.23）和基因多样性（H _exp= 0.45至0.57）。克隆校正后，分子变异分析表明66％的遗传变异发生在两个紫杉之间从单个植物的相同种子头收集的分离株表明，许多带有多重菌核的种子头被子囊孢子而不是分生孢子感染。但是，本研究中获得的大多数克隆分离株均来自同一种子头（即，两个分离株是相同的MLG），表明分生孢子（蜜瓜）在种子头内继发感染中的作用。观察到来自不同寄主的种群之间的遗传分化（22％），但因地理位置而混淆。在四个种群中，标准化的关联指数在0.007至0.122之间，这表明田间潜在的交叉和子囊孢子和分生孢子对麦角的相对贡献存在差异。