Wang Wen-Xuan, Kusari Souvik, Sezgin Selahaddin, Lamshöft Marc, Kusari Parijat, Kayser Oliver, Spiteller Michael
Institute of Environmental Research (INFU), Department of Chemistry and Chemical Biology, Chair of Environmental Chemistry and Analytical Chemistry, TU Dortmund, Otto-Hahn-Str. 6, 44221, Dortmund, Germany.
Appl Microbiol Biotechnol. 2015 Sep;99(18):7651-62. doi: 10.1007/s00253-015-6653-7. Epub 2015 May 12.
The basis of chemical crosstalk in plants and associated endophytes lies in certain so-called communication molecules that are responsible for plant-microbe and microbe-microbe interactions. Consequently, elucidating the factors that affect the nature, distribution, and amount of these molecules and how they impact the interaction among endophytes and associated organisms is essential to understand the true potential of endophytes. In the present study, we report the discovery of nine hexacyclopeptides from an endophytic fungus, Fusarium solani, isolated from the bulb of Narcissus tazetta, and their selective accumulation by an endophytic bacterium, Achromobacter xylosoxidans isolated from the same tissue. We used matrix-assisted laser desorption ionization imaging high-resolution mass spectrometry (MALDI-imaging-HRMS) to firstly identify and visualize the spatial distribution of the hexacyclopeptides produced by endophytic F. solani. After culture condition optimization, their sequence was identified to be cyclo((Hyp or Dhp)-Xle-Xle-(Ala or Val)-Thr-Xle) (Dhp: dehydroproline) by the characteristic a, b, or y ions using liquid chromatography tandem mass spectrometry (LC-HRMS(n)). These hexacyclopeptides were confirmed to be fungal biosynthetic products by deuterium labeling experiments. Finally, in order to understand the plausible ecological relevance of one or more of the discovered hexacyclopeptides within the contexts of microbial "neighbor communication," we devised a dual-culture setup to visualize using MALDI-imaging-HRMS how the hexacyclopeptides released by the endophytic fungus are accumulated by another endophytic bacterium, A. xylosoxidans, isolated from the same bulb tissue. This work exemplifies the relevance of cyclopeptides in endophyte-endophyte interspecies neighbor communication occurring in nature. Such communication strategies are evolved by coexisting endophytes to survive and function in their distinct ecological niches.
植物与其相关内生菌之间化学信号交流的基础在于某些所谓的信号分子，这些分子负责植物与微生物以及微生物与微生物之间的相互作用。因此，阐明影响这些分子的性质、分布和数量的因素，以及它们如何影响内生菌与相关生物之间的相互作用，对于理解内生菌的真正潜力至关重要。在本研究中，我们报告了从水仙鳞茎中分离出的内生真菌茄病镰刀菌中发现的九种六环肽，以及从同一组织中分离出的内生细菌木糖氧化无色杆菌对它们的选择性积累。我们首先使用基质辅助激光解吸电离成像高分辨率质谱（MALDI-成像-HRMS）来鉴定和可视化内生茄病镰刀菌产生的六环肽的空间分布。在优化培养条件后，使用液相色谱串联质谱（LC-HRMS(n)）通过特征性的a、b或y离子确定它们的序列为环（（Hyp或Dhp）-Xle-Xle-（Ala或Val）-Thr-Xle）（Dhp：脱氢脯氨酸）。通过氘标记实验证实这些六环肽是真菌生物合成产物。最后，为了了解在微生物“邻域通讯”背景下一种或多种已发现的六环肽可能的生态相关性，我们设计了一种共培养装置，使用MALDI-成像-HRMS可视化从同一鳞茎组织中分离出的内生真菌释放的六环肽如何被另一种内生细菌木糖氧化无色杆菌积累。这项工作例证了环肽在自然界中发生的内生菌-内生菌种间邻域通讯中的相关性。这种通讯策略是共存的内生菌为了在其独特的生态位中生存和发挥功能而进化出来的。
