Target spot, caused by the fungus Corynespora cassiicola, has been an increasing problem for soybean growers in the Mid-south and southeastern United States. With favorable environmental conditions, the disease causes premature defoliation and substantial yield losses; therefore, identifying resistant germplasm is critical. Herein, a rapid screening technique for target spot resistance was used to evaluate varieties for possible use in a breeding program. Fifteen soybean varieties, along with a known susceptible variety, were evaluated against isolate C. cassiicola LIM01. Two of the sixteen varieties were identified as resistant and nine were moderately susceptible. A subset of these was evaluated with three additional C. cassiicola isolates; these isolates differed in combinations of cassiicolin-encoding genes. The soybean varieties Bedford and Council were observed to be resistant to each of the C. cassiicola isolates tested in this study but need to be further validated in a field environment. Plant populations developed using these parent varieties could provide a foundation for QTL mapping of regions conferring resistance to target spot and identifying disease resistance mechanisms that can be transferred into elite soybean varieties through marker-assisted breeding.

由真菌Corynespora cassiicola引起的靶斑已成为美国中南部和东南部大豆种植者日益严重的问题。在有利的环境条件下，该病害会导致过早落叶和大量减产；因此，鉴定抗性种质至关重要。在此，一种针对目标斑点抗性的快速筛选技术用于评估可能用于育种计划的品种。针对分离株C. cassiicola LIM01评估了 15 个大豆品种以及一个已知的易感品种。十六个品种中有两个被确定为抗性品种，九个为中度敏感品种。其中的一个子集用三个额外的C. cassiicola进行了评估分离；这些分离株在卡西科林编码基因的组合上有所不同。观察到大豆品种 Bedford 和 Council 对本研究中测试的每种C. cassiicola分离株具有抗性，但需要在田间环境中进一步验证。使用这些亲本品种开发的植物种群可以为赋予目标斑点抗性的区域的 QTL 定位提供基础，并确定可以通过标记辅助育种将其转移到优良大豆品种中的抗病机制。