Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, 606-8502, Japan.
Arch Microbiol. 2013 Nov;195(10-11):717-26. doi: 10.1007/s00203-013-0922-6. Epub 2013 Sep 15.
Methanotrophs are widespread and have been isolated from various environments including the phyllosphere. In this study, we characterized the plant colonization by Methylosinus sp. B4S, an α-proteobacterial methanotroph isolated from plant leaf. The gfp-tagged Methylosinus sp. B4S cells were observed to colonize Arabidopsis leaf surfaces by forming aggregates. We cloned and sequenced the general stress response genes, phyR, nepR and ecfG, from Methylosinus sp. B4S. In vitro analysis showed that the phyR expression level was increased after heat shock challenge, and phyR was shown to be involved in resistance to heat shock and UV light. In the phyllospheric condition, the gene expression level of phyR as well as mmoX and mxaF was found to be relatively high, compared with methane-grown liquid cultures. The phyR-deletion strain as well as the wild-type strain inoculated on Arabidopsis leaves proliferated at the initial phase and then gradually decreased during plant colonization. These results have shed light firstly on the importance of general stress resistance and C1 metabolism in methanotroph living in the phyllosphere.
产甲烷菌广泛存在于各种环境中，包括叶片。在这项研究中，我们研究了从植物叶片中分离出来的 α 变形菌产甲烷菌 Methylosinus sp. B4S 对植物的定殖特性。观察到 gfp 标记的 Methylosinus sp. B4S 细胞通过形成聚集体定植在拟南芥叶片表面。我们从 Methylosinus sp. B4S 中克隆并测序了一般应激反应基因 phyR、nepR 和 ecfG。体外分析表明，phyR 的表达水平在热休克挑战后增加，phyR 参与了对热休克和紫外线的抵抗。在叶际条件下，与甲烷生长的液体培养物相比，phyR 以及 mmoX 和 mxaF 的基因表达水平相对较高。phyR 缺失株和接种在拟南芥叶片上的野生型菌株在初始阶段增殖，然后在植物定殖过程中逐渐减少。这些结果首次阐明了一般应激抗性和 C1 代谢在叶际生活的产甲烷菌中的重要性。
