Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation and College of Life Sciences, Fujian Normal University, Fuzhou, Fujian, 350108, China.
State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan and The Key Laboratory for Southwest Microbial Diversity of the Ministry of Education, Yunnan University, Kunming, Yunnan, 650091, China.
Microbiome. 2023 Mar 10;11(1):48. doi: 10.1186/s40168-023-01484-3.
Root-knot nematodes (RKN) are among the most important root-damaging plant-parasitic nematodes, causing severe crop losses worldwide. The plant rhizosphere and root endosphere contain rich and diverse bacterial communities. However, little is known about how RKN and root bacteria interact to impact parasitism and plant health. Determining the keystone microbial taxa and their functional contributions to plant health and RKN development is important for understanding RKN parasitism and developing efficient biological control strategies in agriculture.
The analyses of rhizosphere and root endosphere microbiota of plants with and without RKN showed that host species, developmental stage, ecological niche, and nematode parasitism, as well as most of their interactions, contributed significantly to variations in root-associated microbiota. Compared with healthy tomato plants at different developmental stages, significant enrichments of bacteria belonging to Rhizobiales, Betaproteobacteriales, and Rhodobacterales were observed in the endophytic microbiota of nematode-parasitized root samples. Functional pathways related to bacterial pathogenesis and biological nitrogen fixation were significantly enriched in nematode-parasitized plants. In addition, we observed significant enrichments of the nifH gene and NifH protein, the key gene/enzyme involved in biological nitrogen fixation, within nematode-parasitized roots, consistent with a potential functional contribution of nitrogen-fixing bacteria to nematode parasitism. Data from a further assay showed that soil nitrogen amendment could reduce both endophytic nitrogen-fixing bacteria and RKN prevalence and galling in tomato plants.
Results demonstrated that (1) community variation and assembly of root endophytic microbiota were significantly affected by RKN parasitism; (2) a taxonomic and functional association was found for endophytic nitrogen-fixing bacteria and nematode parasitism; and (3) the change of nitrogen-fixing bacterial communities through the addition of nitrogen fertilizers could affect the occurrence of RKN. Our results provide new insights into interactions among endophytic microbiota, RKN, and plants, contributing to the potential development of novel management strategies against RKN. Video Abstract.
根结线虫（RKN）是最重要的破坏植物根系的植物寄生线虫之一，在全球范围内造成严重的作物损失。植物根际和根内含有丰富多样的细菌群落。然而，人们对 RKN 与根细菌如何相互作用以影响寄生和植物健康知之甚少。确定关键微生物类群及其对植物健康和 RKN 发育的功能贡献对于理解 RKN 寄生和开发农业中有效的生物防治策略非常重要。
对有和没有 RKN 的植物的根际和根内微生物群落进行分析表明，宿主物种、发育阶段、生态位以及线虫寄生，以及它们的大部分相互作用，对根系相关微生物群落的变化有显著影响。与不同发育阶段的健康番茄植物相比，在被线虫寄生的根样本的内生微生物群落中，属于根瘤菌目、β-变形菌目和红杆菌目的细菌明显富集。与细菌发病机制和生物固氮相关的功能途径在被线虫寄生的植物中明显富集。此外，我们观察到线虫寄生根内固氮关键基因/nifH 蛋白的 nifH 基因明显富集，这与固氮细菌对线虫寄生的潜在功能贡献一致。进一步的实验结果表明，土壤氮素添加可以减少番茄植物内生固氮细菌和 RKN 的丰度和根结瘤。
结果表明：（1）根内生微生物群落的群落变化和组装受到 RKN 寄生的显著影响；（2）发现内生固氮细菌与线虫寄生之间存在分类和功能关联；（3）通过添加氮肥改变固氮细菌群落会影响 RKN 的发生。我们的研究结果为内生微生物群落、RKN 和植物之间的相互作用提供了新的见解，有助于开发针对 RKN 的新管理策略。
