Exploring the symbiotic pangenome of the nitrogen-fixing bacterium Sinorhizobium meliloti.
Exploring the symbiotic pangenome of the nitrogen-fixing bacterium Sinorhizobium meliloti.
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DOI：
10.1186/1471-2164-12-235
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发表时间：
2011-05-12
期刊：
影响因子：
4.4
通讯作者：
Biondi EG
中科院分区：
文献类型：
--
作者：
Galardini M;Mengoni A;Brilli M;Pini F;Fioravanti A;Lucas S;Lapidus A;Cheng JF;Goodwin L;Pitluck S;Land M;Hauser L;Woyke T;Mikhailova N;Ivanova N;Daligault H;Bruce D;Detter C;Tapia R;Han C;Teshima H;Mocali S;Bazzicalupo M;Biondi EG
苜蓿中华根瘤菌是研究共生固氮的模式系统。一个广泛的多态性在遗传和表型水平是本物种的自然种群，特别是在植物生长的共生促进。AK 83和BL 225 C是两个根瘤分离菌株，具有不同的共生表型; BL 225 C比菌株AK 83更有效地促进紫花苜蓿植物的生长。为了探讨S.苜蓿属菌株AK 83和BL 225 C，我们测定了这两个菌株的全基因组。AK 83和BL 225 C的基因组大小分别为7.14 Mbp和6.97 Mbp，比实验室菌株Rm 1021大。Rm 1021、AK 83、BL 225 C菌株的核心基因组包括5124个直链组，辅助基因组由2700个直链组组成。Rm 1021和BL 225 C只有三个复制子（染色体，pSymA和pSymB），而AK 83也有两个质粒，260和70 Kbp长。我们发现了65个有趣的直向同源基因组，它们只存在于辅助基因组中，因此负责表型多样性和参与植物-细菌相互作用的puplex。值得注意的是，共生效率低的AK 83缺乏几个基因所需的微需氧生长的结节内，而几个基因的辅助功能相关的竞争，植物入侵和类菌体嗜性被确定只有在AK 83和BL 225 C菌株。还分析了参与共生相互作用的转录因子调节子的多态性的存在和程度。我们的研究结果表明，调节子是灵活的，有大量的辅助基因，这表明调节子多态性也可能是一个关键的决定因素之间的共生性能的变异分析菌株。总之，扩展的比较基因组学方法揭示了可能有助于共生多样性的基因和调节子的可变子集。
Sinorhizobium meliloti is a model system for the studies of symbiotic nitrogen fixation. An extensive polymorphism at the genetic and phenotypic level is present in natural populations of this species, especially in relation with symbiotic promotion of plant growth. AK83 and BL225C are two nodule-isolated strains with diverse symbiotic phenotypes; BL225C is more efficient in promoting growth of the Medicago sativa plants than strain AK83. In order to investigate the genetic determinants of the phenotypic diversification of S. meliloti strains AK83 and BL225C, we sequenced the complete genomes for these two strains. With sizes of 7.14 Mbp and 6.97 Mbp, respectively, the genomes of AK83 and BL225C are larger than the laboratory strain Rm1021. The core genome of Rm1021, AK83, BL225C strains included 5124 orthologous groups, while the accessory genome was composed by 2700 orthologous groups. While Rm1021 and BL225C have only three replicons (Chromosome, pSymA and pSymB), AK83 has also two plasmids, 260 and 70 Kbp long. We found 65 interesting orthologous groups of genes that were present only in the accessory genome, consequently responsible for phenotypic diversity and putatively involved in plant-bacterium interaction. Notably, the symbiosis inefficient AK83 lacked several genes required for microaerophilic growth inside nodules, while several genes for accessory functions related to competition, plant invasion and bacteroid tropism were identified only in AK83 and BL225C strains. Presence and extent of polymorphism in regulons of transcription factors involved in symbiotic interaction were also analyzed. Our results indicate that regulons are flexible, with a large number of accessory genes, suggesting that regulons polymorphism could also be a key determinant in the variability of symbiotic performances among the analyzed strains. In conclusions, the extended comparative genomics approach revealed a variable subset of genes and regulons that may contribute to the symbiotic diversity.
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影响因子：
3.9
作者：
Babu, M. Madan
通讯作者：
Babu, M. Madan
影响因子：
3.2
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DEBELLE, F;ROSENBERG, C;TRUCHET, G
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TRUCHET, G
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Brilli, Matteo;Fondi, Marco;Biondi, Emanuele G.
通讯作者：
Biondi, Emanuele G.
影响因子：
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