Division of Plant Sciences and Bond Life Sciences Center, University of Missouri, Columbia, MO 65211.
Agriculture Experiment Station Statistician, University of Missouri, Columbia, MO 65211.
Plant Dis. 2021 Oct;105(10):3238-3243. doi: 10.1094/PDIS-12-20-2556-RE. Epub 2021 Nov 9.
Soybean cyst nematode (SCN) is an important pathogen of soybean causing >$1 billion in yield losses annually in the United States. Planting SCN-resistant soybean cultivars is the primary management strategy. Resistance genes derived from the plant introduction (PI) 88788 () and PI 548402 (Peking; and ) are the main types of resistance available in commercial cultivars. The PI 88788 resistance allele is found in the majority of SCN-resistant cultivars in the north central United States. The widespread use of PI 88788 has led to limited options for farmers to rotate resistance sources to manage SCN. Consequently, overreliance on a single type of resistance has resulted in the selection of SCN populations that have adapted to reproduce on these resistant cultivars. Here we evaluated the effectiveness of rotating soybean lines with different combinations of resistance genes to determine the best strategy for combating the widespread increase in virulent SCN and limit future nematode adaptation to resistant cultivars. Eight SCN populations were developed by continuous selection of a virulent SCN field population ( [HG] type 1.2.5.7) on a single resistance source or in rotation with soybean pyramiding different resistance gene alleles derived from PI 88788 (), PI 437654 ( and ), PI 468916 ( and ), and PI 567516C (). SCN population densities were determined for eight generations. HG type tests were conducted after the eighth generation to evaluate population shifts. The continued use of or had limited effectiveness for reducing SCN type 1.2.5.7 population density, whereas rotation to the use of / resistance significantly reduced SCN population density but selected for broader SCN virulence (HG type 1.2.3.5.6.7). A rotation of / with a pyramid of / was the most effective combination at both reducing population density and minimizing selection pressure. Our results provide guidance for implementation of a strategic SCN resistance rotation plan to manage the widespread virulence on PI 88788 and sustain the future durability of SCN resistance genes.
大豆胞囊线虫（SCN）是一种重要的大豆病原体，每年给美国造成超过 10 亿美元的产量损失。种植抗 SCN 的大豆品种是主要的管理策略。来自植物引种（PI）88788（）和 PI 548402（北京；和）的抗性基因是商业品种中主要的抗性类型。PI 88788 抗性等位基因存在于美国中北部大多数抗 SCN 品种中。PI 88788 的广泛使用导致农民选择有限的抗性来源来管理 SCN，从而导致对单一类型抗性的过度依赖，导致选择适应这些抗性品种的 SCN 种群。在这里，我们评估了不同组合的抗性基因的大豆品系轮换的有效性，以确定对抗广泛增加的毒力 SCN 和限制未来线虫适应抗性品种的最佳策略。通过在单个抗性源上连续选择毒力 SCN 田间种群（[HG] 1.2.5.7 型），或与大豆聚积不同抗性基因等位基因（来自 PI 88788（）、PI 437654（和）、PI 468916（和）和 PI 567516C（））轮换，开发了八个 SCN 种群。对八个世代的 SCN 种群密度进行了测定。在第八代后进行 HG 型测试，以评估种群变化。继续使用或具有有限的有效性，可降低 SCN 1.2.5.7 种群密度，而轮换使用/抗性则显著降低 SCN 种群密度，但选择了更广泛的 SCN 毒力（HG 型 1.2.3.5.6.7）。/与/聚积的轮换是降低种群密度和最小化选择压力的最有效组合。我们的结果为实施战略 SCN 抗性轮换计划提供了指导，以管理 PI 88788 上广泛的毒力并维持 SCN 抗性基因的未来耐久性。
