Rhizobium-legume symbiosis shares an exocytotic pathway required for arbuscule formation
Rhizobium-legume symbiosis shares an exocytotic pathway required for arbuscule formation
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DOI：
10.1073/pnas.1200407109
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发表时间：
2012-05-22
影响因子：
11.1
通讯作者：
Bisseling, Ton
中科院分区：
文献类型：
--
作者：
Ivanov, Sergey;Fedorova, Elena E.;Bisseling, Ton
内共生相互作用的特征在于由宿主以细胞内方式形成专门的膜隔室。广泛存在的丛枝菌根共生和根瘤菌-豆科植物共生是两个研究得很好的具有重要农业和生态意义的例子。在这两种共生体中，围绕微生物的特化宿主膜形成共生界面，这有助于以受控的方式交换例如营养物质，因此形成内共生的核心。尽管它们的关键重要性，这些膜界面形成的分子和细胞机制在很大程度上是未知的。近年来的研究表明，根瘤菌与豆科植物的共生系统是从古老的丛枝菌根共生系统中借鉴了包括受体在内的信号传导途径，从而形成了一个共生界面。在这里，我们表明，两个高度同源的胞吐囊泡相关膜蛋白（VAMPs）的共生膜界面的形成所需的两个相互作用。这些苜蓿VAMP 72基因的沉默对非共生植物发育和根瘤形成有轻微影响。然而，它会阻止共生体和丛枝的形成，而微生物的根部定殖不受影响。这些VAMP 72作为胞吐囊泡运输中常见的共生调节剂的鉴定表明，形成丛枝周围膜隔室的古老胞吐途径也已在根瘤菌-豆科植物共生中被吸收。
Endosymbiotic interactions are characterized by the formation of specialized membrane compartments, by the host in which the microbes are hosted, in an intracellular manner. Two well-studied examples, which are of major agricultural and ecological importance, are the widespread arbuscular mycorrhizal symbiosis and the Rhizobium-legume symbiosis. In both symbioses, the specialized host membrane that surrounds the microbes forms a symbiotic interface, which facilitates the exchange of, for example, nutrients in a controlled manner and, therefore, forms the heart of endosymbiosis. Despite their key importance, the molecular and cellular mechanisms underlying the formation of these membrane interfaces are largely unknown. Recent studies strongly suggest that the Rhizobium-legume symbiosis coopted a signaling pathway, including receptor, from the more ancient arbuscular mycorrhizal symbiosis to form a symbiotic interface. Here, we show that two highly homologous exocytotic vesicle-associated membrane proteins (VAMPs) are required for formation of the symbiotic membrane interface in both interactions. Silencing of these Medicago VAMP72 genes has a minor effect on nonsymbiotic plant development and nodule formation. However, it blocks symbiosome as well as arbuscule formation, whereas root colonization by the microbes is not affected. Identification of these VAMP72s as common symbiotic regulators in exocytotic vesicle trafficking suggests that the ancient exocytotic pathway forming the periarbuscular membrane compartment has also been coopted in the Rhizobium-legume symbiosis.