Grazing of a common species of soil protozoa (Acanthamoeba castellanii) affects rhizosphere bacterial community composition and root architecture of rice (Oryza sativa L.)
Grazing of a common species of soil protozoa (Acanthamoeba castellanii) affects rhizosphere bacterial community composition and root architecture of rice (Oryza sativa L.)
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DOI：
10.1016/j.soilbio.2005.11.027
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发表时间：
2006-07-01
影响因子：
9.7
通讯作者：
Bonkowski, M.
中科院分区：
文献类型：
--
作者：
Kreuzer, K.;Adamczyk, J.;Bonkowski, M.
研究人员对培养皿中生长的水稻幼苗（Oryza sativa L.）进行了对照实验。培养皿中含有一个简单的根际食物网，该食物网由多种细菌群落和常见的土壤原生动物棘阿米巴（Acanthamoeba castellanii）作为细菌食草动物。变形虫的存在增加了细菌的活性，并显著改变了根际细菌的群落组成和空间分布。特别是，β变形菌确实受益于原生动物的放牧。我们推测细菌群落组成的变化影响了水稻植株的根构型。这些对根构型的影响影响着植物生产力的一个基本方面。存在原生动物的根系具有大量的细长（l型）侧根，这些侧根是构建分枝根系的先决条件。这与没有原生动物的情况下根系发育形成鲜明对比，在没有原生动物的情况下，出现了大量侧根原基和短侧根（s型），这些侧根不长出轴根的根际区域。由于放牧细菌的养分释放和根结构的变化，在原生动物存在的情况下，水稻幼苗的氮含量增加了45%。我们的研究表明，在三个营养水平上，即植物、细菌和原生动物之间的相互作用显著地改变了植物的根结构和营养吸收。(c) 2006 Elsevier Ltd.版权所有。
We performed a controlled experiment with rice seedlings (Oryza sativa L.) growing in Petri dishes on homogeneous nutrient agar containing a simple rhizosphere food web consisting of a diverse bacterial community and a common soil protozoa, Acanthamoeba castellanii, as bacterial grazer. Presence of amoebae increased bacterial activity and significantly changed the community composition and spatial distribution of bacteria in the rhizosphere. In particular, Betaproteobacteria did benefit from protozoan grazing. We hypothesize that the changes in bacterial community composition affected the root architecture of rice plants. These effects on root architecture affect a fundamental aspect of plant productivity. Root systems in presence of protozoa were characterized by high numbers of elongated (L-type) laterals, those laterals that are a prerequisite for the construction of branched root systems. This was in sharp contrast to root system development in absence of protozoa, where high numbers of lateral root primordia and short (S-type) laterals occurred which did not grow out of the rhizosphere region of the axile root. As a consequence of-nutrient release from grazed bacteria and changes in root architecture, the nitrogen content of rice shoots increased by 45% in presence of protozoa. Our study illustrates that interactions over three trophic levels, i.e. between plants, bacteria and protozoa significantly modify root architecture and nutrient uptake by plants. (c) 2006 Elsevier Ltd. All rights reserved.