Bent E, Loffredo A, McKenry M V, Becker J O, Borneman J
Department of Plant Pathology and Microbiology and Department of Nematology, University of California, Riverside, CA 92521, USA.
J Nematol. 2008 Jun;40(2):109-18.
Greenhouse experiments with two susceptible hosts of Meloidogyne incognita, a dwarf tomato and wheat, led to the identification of a soil in which the root-knot nematode population was reduced 5- to 16-fold compared to identical but pasteurized soil two months after infestation with 280 M. incognita J2/100 cm(3) soil. This suppressive soil was subjected to various temperature, fumigation and dilution treatments, planted with tomato, and infested with 1,000 eggs of M. incognita/100 cm(3) soil. Eight weeks after nematode infestation, distinct differences in nematode population densities were observed among the soil treatments, suggesting the suppressiveness had a biological nature. A fungal rRNA gene analysis (OFRG) performed on M. incognita egg masses collected at the end of the greenhouse experiments identified 11 fungal phylotypes, several of which exhibited associations with one or more of the nematode population density measurements (egg masses, eggs or J2). The phylotype containing rRNA genes with high sequence identity to Pochonia chlamydosporia exhibited the strongest negative associations. The negative correlation between the densities of the P. chlamydosporia genes and the nematodes was corroborated by an analysis using a P. chlamydosporia-selective qPCR assay.
用南方根结线虫的两种感病寄主——矮化番茄和小麦进行温室试验，结果发现一种土壤，在每100立方厘米土壤接种280条南方根结线虫二龄幼虫两个月后，与相同但经过巴氏消毒的土壤相比，该土壤中根结线虫种群数量减少了5至16倍。对这种抑病土壤进行了各种温度、熏蒸和稀释处理，种植番茄，并在每100立方厘米土壤中接种1000粒南方根结线虫卵。线虫接种八周后，在土壤处理之间观察到线虫种群密度存在明显差异，这表明这种抑制作用具有生物学性质。在温室试验结束时收集的南方根结线虫卵块上进行的真菌核糖体RNA基因分析（OFRG）鉴定出11种真菌系统型，其中几种与一种或多种线虫种群密度测量值（卵块、卵或二龄幼虫）存在关联。与厚垣普可尼亚菌的rRNA基因具有高度序列同一性的系统型表现出最强的负相关。使用厚垣普可尼亚菌选择性定量PCR分析进一步证实了厚垣普可尼亚菌基因密度与线虫之间的负相关性。
