Transcriptomic Analysis of Rhizobium leguminosarum Biovar viciae in Symbiosis with Host Plants Pisum sativum and Vicia cracca
Transcriptomic Analysis of Rhizobium leguminosarum Biovar viciae in Symbiosis with Host Plants Pisum sativum and Vicia cracca
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DOI：
10.1128/jb.00165-09
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发表时间：
2009-06-15
影响因子：
3.2
通讯作者：
Poole, P. S.
中科院分区：
文献类型：
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作者：
Karunakaran, R.;Ramachandran, V. K.;Poole, P. S.
豆科根瘤菌vicicae在豌豆（Pisum sativum）和豇豆（Vicia cracca）等几种豆科植物上形成固氮根瘤，并被广泛用作研究根瘤生物化学的模型。为了解豆科植物的复杂生化和发育变化。在类细菌发育过程中，首先对培养在各种碳底物（葡萄糖、丙酮酸、琥珀酸、肌醇、醋酸酯和醋酸酯）上的细菌进行微阵列实验，然后与类细菌进行比较。类杆菌代谢本质上是二羧酸生长细胞的代谢（即诱导二羧酸转运、糖异生和丙氨酸合成，以及抑制糖利用）。三羧酸循环的脱羧臂是高度诱导的，γ -氨基丁酸代谢也是如此，特别是在早期（7天）结核的类细菌中。为了研究类杆菌的发育，在豌豆接种后7、15和21天分析了类杆菌的基因表达。这表明从豌豆而不是豌豆中分离的细菌rRNA在成熟的类细菌中被广泛加工。在发育早期（7天），调节因子、输出和细胞表面分子、多药输出蛋白、热休克蛋白和冷休克蛋白的表达发生了很大变化。固定基因在成熟的类杆菌中被早期诱导，但持续增加，而nif基因在较老的类杆菌中被强烈诱导。37个在成熟类细菌中强烈上调的基因突变表明，没有一个是固氮所必需的。然而，对3072个豌豆mini-Tn5突变体的筛选揭示了以前未被发现的固氮必需基因。它们编码了一个潜在的镁转运蛋白、一个AAA结构域蛋白和参与细胞色素合成的蛋白。
Rhizobium leguminosarum bv. viciae forms nitrogen-fixing nodules on several legumes, including pea (Pisum sativum) and vetch (Vicia cracca), and has been widely used as a model to study nodule biochemistry. To understand the complex biochemical and developmental changes undergone by R. leguminosarum bv. viciae during bacteroid development, microarray experiments were first performed with cultured bacteria grown on a variety of carbon substrates (glucose, pyruvate, succinate, inositol, acetate, and acetoacetate) and then compared to bacteroids. Bacteroid metabolism is essentially that of dicarboxylate-grown cells (i.e., induction of dicarboxylate transport, gluconeogenesis and alanine synthesis, and repression of sugar utilization). The decarboxylating arm of the tricarboxylic acid cycle is highly induced, as is gamma-aminobutyrate metabolism, particularly in bacteroids from early (7-day) nodules. To investigate bacteroid development, gene expression in bacteroids was analyzed at 7, 15, and 21 days postinoculation of peas. This revealed that bacterial rRNA isolated from pea, but not vetch, is extensively processed in mature bacteroids. In early development (7 days), there were large changes in the expression of regulators, exported and cell surface molecules, multidrug exporters, and heat and cold shock proteins. fix genes were induced early but continued to increase in mature bacteroids, while nif genes were induced strongly in older bacteroids. Mutation of 37 genes that were strongly upregulated in mature bacteroids revealed that none were essential for nitrogen fixation. However, screening of 3,072 mini-Tn5 mutants on peas revealed previously uncharacterized genes essential for nitrogen fixation. These encoded a potential magnesium transporter, an AAA domain protein, and proteins involved in cytochrome synthesis.