Adam Mohamed, Westphal Andreas, Hallmann Johannes, Heuer Holger
Julius Kühn Institut-Federal Research Centre for Cultivated Plants, Braunschweig, Germany.
Appl Environ Microbiol. 2014 May;80(9):2679-86. doi: 10.1128/AEM.03905-13. Epub 2014 Feb 14.
Understanding the interactions of plant-parasitic nematodes with antagonistic soil microbes could provide opportunities for novel crop protection strategies. Three arable soils were investigated for their suppressiveness against the root knot nematode Meloidogyne hapla. For all three soils, M. hapla developed significantly fewer galls, egg masses, and eggs on tomato plants in unsterilized than in sterilized infested soil. Egg numbers were reduced by up to 93%. This suggested suppression by soil microbial communities. The soils significantly differed in the composition of microbial communities and in the suppressiveness to M. hapla. To identify microorganisms interacting with M. hapla in soil, second-stage juveniles (J2) baited in the test soil were cultivation independently analyzed for attached microbes. PCR-denaturing gradient gel electrophoresis of fungal ITS or 16S rRNA genes of bacteria and bacterial groups from nematode and soil samples was performed, and DNA sequences from J2-associated bands were determined. The fingerprints showed many species that were abundant on J2 but not in the surrounding soil, especially in fungal profiles. Fungi associated with J2 from all three soils were related to the genera Davidiella and Rhizophydium, while the genera Eurotium, Ganoderma, and Cylindrocarpon were specific for the most suppressive soil. Among the 20 highly abundant operational taxonomic units of bacteria specific for J2 in suppressive soil, six were closely related to infectious species such as Shigella spp., whereas the most abundant were Malikia spinosa and Rothia amarae, as determined by 16S rRNA amplicon pyrosequencing. In conclusion, a diverse microflora specifically adhered to J2 of M. hapla in soil and presumably affected female fecundity.
了解植物寄生线虫与拮抗性土壤微生物之间的相互作用可为新型作物保护策略提供机会。研究了三种耕地土壤对根结线虫南方根结线虫的抑制作用。对于所有这三种土壤，南方根结线虫在未灭菌的番茄植株上形成的虫瘿、卵块和卵显著少于灭菌的受侵染土壤。卵数减少了高达93%。这表明土壤微生物群落具有抑制作用。这些土壤在微生物群落组成和对南方根结线虫的抑制性方面存在显著差异。为了鉴定与土壤中南方根结线虫相互作用的微生物，对在测试土壤中诱捕的二龄幼虫（J2）附着的微生物进行了独立培养分析。对线虫和土壤样品中的真菌ITS或细菌及细菌类群的16S rRNA基因进行了PCR-变性梯度凝胶电泳，并测定了J2相关条带的DNA序列。指纹图谱显示，许多物种在J2上丰富，但在周围土壤中不存在，尤其是在真菌图谱中。来自所有三种土壤的与J2相关的真菌与Davidiella属和Rhizophydium属有关，而曲霉菌属、灵芝属和柱孢属则是最具抑制性土壤特有的。在抑制性土壤中J2特有的20个高度丰富的细菌操作分类单元中，有6个与感染性物种如志贺氏菌属密切相关，而通过16S rRNA扩增子焦磷酸测序确定，最丰富的是棘刺马利克氏菌和苦味罗思氏菌。总之，多种微生物群落特异性地附着在土壤中南方根结线虫的J2上，并可能影响雌虫的繁殖力。
