In Rhizobium etli symbiotic plasmid transfer, nodulation competitivity and cellular growth require interaction among different replicons
In Rhizobium etli symbiotic plasmid transfer, nodulation competitivity and cellular growth require interaction among different replicons
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DOI：
10.1006/plas.2000.1469
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发表时间：
2000-07-01
期刊：
影响因子：
2.6
通讯作者：
Romero, D
中科院分区：
文献类型：
--
作者：
Brom, S;García-de los Santos, A;Romero, D
属于根瘤菌属的细菌能够发展两种不同的生活方式，与植物根共生或通过腐殖生长。根瘤菌的基因组由一条染色体和几个大的质粒组成。其中之一含有大多数参与共生的基因（共生质粒或pSym）。我们的模式菌株Rhizobium etli CFN42含有6个质粒。我们已经构建了这种菌株的多个质粒固化衍生物，并使用它们来分析这些质粒对自由生活的细胞活力、竞争力、质粒转移和利用不同碳源的贡献。我们的结果表明，pSym的转移是严格依赖于另一个质粒的存在：因此，在需要pSym转移的条件下，重组依赖于缺乏重组基因的质粒的存在。我们还发现，与单一质粒固化菌株相比，在多个质粒固化衍生物中的结晶竞争力急剧下降。在一些多重质粒治愈的菌株中，细胞生长和活力大大降低。许多碳源的利用取决于特定质粒的存在。这项工作的结果表明，分散在不同质粒中的序列之间的功能相互作用是成功完成两种生活方式所必需的。(C)北京大学出版社.
Bacteria belonging to the genus Rhizobium are able to develop two different lifestyles, in symbiotic association with plant roots or through saprophytic growth. The genome of Rhizobium strains is constituted by a chromosome and several large plasmids. one of them containing most of the genes involved in symbiosis (symbiotic plasmid or pSym). Our model strain Rhizobium etli CFN42 contains six plasmids. We have constructed multiple plasmid-cured derivatives of this strain and used them to analyze the contribution of these plasmids to free-living cellular viability, competitivity for nodulation, plasmid transfer, and utilization of diverse carbon sources. Our results show that the transfer of the pSym is strictly dependent on the presence of another plasmid: consequently under conditions where pSym transfer is required, nodulation relies on the presence of a plasmid devoid of nodulation genes. We also found a drastic decrease in competitivity for nodulation in multiple plasmid-cured derivatives when compared with single plasmid-cured strains. Cellular growth and viability were greatly diminished in some multiple plasmid-cured strains. The utilization of a number of carbon sources depends on the presence of specific plasmids. The results presented in this work indicate that Functional interactions among sequences scattered in the different plasmids are required for successful completion of both lifestyles. (C) 2000 Academic Press.