Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland.
FEMS Microbiol Lett. 2013 Dec;349(2):117-26. doi: 10.1111/1574-6968.12303. Epub 2013 Nov 18.
Ensifer (Sinorhizobium) arboris is a symbiont of salt-tolerant leguminous trees in the genera Acacia and Prosopis that are utilized in the prevention of soil erosion and desertification and in phytoremediation of salinized soil. Signalling between the plant and the rhizobia is essential for the formation of effective symbiosis that increases the success of reclaiming saline sites. We assessed the effect of salt stress on the growth and the production of lipochitooligosaccharide signalling molecules (LCOs) of S. arboris HAMBI 2361, an LCO-overproducing derivative of the S. arboris type strain HAMBI 1552. The strain tolerated NaCl up to 750 mM. To obtain both qualitative and quantitative information on the LCO production under salt stress, we devised a method where LCOs were differentially labelled by stable isotopes of nitrogen, (14)N and (15)N, and analysed by mass spectrometry. Under control conditions, the strain produced altogether 27 structural LCO variants. In 380 mM NaCl, 13 LCO variants were produced in detectable amounts, and six of these were reliably quantified, ranging from one-tenth to one-third of the non-stressed one.
相思根瘤菌（Sinorhizobium）是耐盐豆科树木（金合欢属和刺槐属）的共生体，可用于防止土壤侵蚀和荒漠化，并用于盐渍土壤的植物修复。植物和根瘤菌之间的信号传递对于形成有效的共生关系至关重要，这可以提高回收盐渍地的成功率。我们评估了盐胁迫对 S. arboris HAMBI 2361（一种 LCO 过度产生的 S. arboris 标准菌株 HAMBI 1552 的衍生物）生长和脂寡糖信号分子（LCOs）产生的影响。该菌株可耐受高达 750 mM 的 NaCl。为了获得盐胁迫下 LCO 产生的定性和定量信息，我们设计了一种方法，通过使用氮的稳定同位素（14N 和 15N）对 LCO 进行差异标记，并通过质谱进行分析。在对照条件下，该菌株总共产生了 27 种结构 LCO 变体。在 380 mM NaCl 下，可检测到 13 种 LCO 变体的产生，其中 6 种可可靠定量，其含量范围为未受胁迫时的十分之一到三分之一。
