Liswadiratanakul Sumetee, Yamamoto Kosuke, Matsutani Minenosuke, Wattanadatsaree Vatanee, Kihara Shunta, Shiwa Yuh, Shiwachi Hironobu
Department of International Agricultural Development, Faculty of International Agriculture and Food Studies, Tokyo University of Agriculture, Tokyo, Japan.
Department of Molecular Microbiology, Faculty of Life Sciences, Tokyo University of Agriculture, Tokyo, Japan.
Front Microbiol. 2023 Feb 6;14:1060239. doi: 10.3389/fmicb.2023.1060239. eCollection 2023.
Biofertilizers containing high-density plant growth-promoting bacteria are gaining interest as a sustainable solution to environmental problems caused by eutrophication. However, owing to the limitations of current investigative techniques, the selected microorganisms are not always preferred by the host plant, preventing recruitment into the native microbiota or failing to induce plant growth-promoting effects. To address this, five nitrogen-fixing bacteria previously isolated from water yam ( L.) plants and showing dominant abundance of 1% or more in the water yam microbiota were selected for analysis of their plant growth-promoting activities when used as a synthetic bacterial inoculant. Water yam cv. A-19 plants were inoculated twice at 10 and 12 weeks after planting under greenhouse conditions. Bacterial communities in root, rhizosphere, and bulk soil samples were characterized using high-throughput 16S rRNA amplicon sequencing. Compared with non-inoculated plants, all bacterial communities were significantly altered by inoculation, mainly at the genus level. The inoculation effects were apparently found in the root communities at 16 weeks after planting, with all inoculated genera showing dominance (in the top 35 genera) compared with the control samples. However, no significant differences in any of the growth parameters or nitrogen contents were observed between treatments. At 20 weeks after planting, the dominance of in the inoculated roots decreased, indicating a decline in the inoculation effects. Interestingly, only the clade was dominant (>1% relative abundance) across all samples, suggesting that bacteria related to this clade are essential core bacteria for water yam growth. This is the first report on addition of a synthetic nitrogen-fixing bacterial community in water yam plants showing that native bacterial communities can be replaced by a synthetic bacterial community, with declining in the effects of on the modified communities several weeks after inoculation.
含有高密度植物促生细菌的生物肥料作为一种解决富营养化所导致环境问题的可持续解决方案，正受到越来越多的关注。然而，由于当前研究技术的局限性，所选择的微生物并不总是受到宿主植物的青睐，从而无法进入原生微生物群或无法诱导植物促生效应。为了解决这一问题，从水芋（L.）植物中分离出的5种固氮细菌被选作分析对象，这些细菌在水芋微生物群中显示出1%或更高的优势丰度，研究其作为合成细菌接种剂时的植物促生活性。水芋品种A - 19植株在温室条件下种植后第10周和第12周进行了两次接种。使用高通量16S rRNA扩增子测序对根、根际和土壤样本中的细菌群落进行了表征。与未接种的植株相比，接种显著改变了所有细菌群落，主要是在属水平上。接种效果在种植后16周时在根群落中明显可见，与对照样本相比，所有接种属均显示出优势（在前35个属中）。然而，各处理之间在任何生长参数或氮含量上均未观察到显著差异。种植后20周，接种根中该属的优势度下降，表明接种效果减弱。有趣的是，只有该进化枝在所有样本中占主导地位（相对丰度>1%），这表明与该进化枝相关的细菌是水芋生长的必需核心细菌。这是关于在水芋植株中添加合成固氮细菌群落的首次报道，表明原生细菌群落可被合成细菌群落取代，接种几周后该属对改良群落的影响减弱。
