Becker Jennifer Smith, Ruegger Paul M, Borneman James, Becker J Ole
Department of Nematology, University of California Riverside, 3401 Watkins Drive, Riverside, CA 92521.
Department of Microbiology and Plant Pathology, University of California Riverside, 3401 Watkins Drive, Riverside, CA 92521.
Phytopathology. 2024 Feb;114(2):334-339. doi: 10.1094/PHYTO-07-23-0221-R. Epub 2024 Feb 5.
The nematophagous fungus and relatives ( spp.) are known to parasitize several endoparasitic nematodes. In this project, we hypothesized that indigenous populations of this fungus could be used to predict nematode suppression in agricultural field soils. We quantified spp. in soil samples from 44 different sugar beet fields in the Imperial Valley of California. Seven soils harboring spp. and two that tested negative for the fungi were examined for nematode suppressive activity. Untreated and autoclaved portions of each soil were planted with cabbage and infested with sugar beet cyst nematode () juveniles. Females and cysts of were enumerated after 12 weeks. In the seven soils harboring spp., females and cysts in the untreated soils were reduced by 61 to 82% compared with the autoclaved controls. Soils with no detectable spp. exhibited no nematode suppression. Two novel strains, HsImV25 and HsImV27, were isolated from females reared in field soil using an enrichment and double-baiting cultivation technique. Both strains suppressed populations by more than 80% in soil-based assays, confirming that spp. are the likely causal agents of the nematode suppression in these soils. This study demonstrated that indigenous populations of a hyperparasite ( spp.) in agricultural field soils predicted suppressive activity against a soilborne plant pathogen (). To our knowledge, this is the first report to demonstrate this capability. We anticipate that this research will provide a blueprint for other similar studies, thereby advancing the field of soilborne biological control.
捕食线虫真菌及其相关物种（ spp.）已知可寄生于几种内寄生线虫。在本项目中，我们假设这种真菌的本地种群可用于预测农业田间土壤中线虫的抑制情况。我们对加利福尼亚帝国谷44个不同甜菜田的土壤样本中的 spp. 进行了定量分析。对7个含有 spp. 的土壤样本和2个检测该真菌呈阴性的土壤样本进行了线虫抑制活性检测。每个土壤样本的未处理部分和经高压灭菌的部分均种植卷心菜，并接种甜菜孢囊线虫（）幼虫。12周后统计 的雌虫和孢囊数量。在7个含有 spp. 的土壤样本中，未处理土壤中的雌虫和孢囊数量相比经高压灭菌的对照减少了61%至82%。未检测到 spp. 的土壤未表现出线虫抑制作用。使用富集和双重诱饵培养技术，从田间土壤中饲养的 雌虫中分离出了两个新的 菌株HsImV25和HsImV27。在基于土壤的试验中，这两个菌株均使 种群数量减少了80%以上，证实 spp. 可能是这些土壤中线虫抑制作用的致病因子。本研究表明，农业田间土壤中一种重寄生菌（ spp.）的本地种群可预测对一种土传植物病原体（）的抑制活性。据我们所知，这是首次证明这种能力的报告。我们预计这项研究将为其他类似研究提供蓝图，从而推动土传生物防治领域的发展。
