Hildebrandt Ulrich, Ouziad Fouad, Marner Franz-Josef, Bothe Hermann
Botanical Institute, University of Cologne, Köln, Germany.
FEMS Microbiol Lett. 2006 Jan;254(2):258-67. doi: 10.1111/j.1574-6968.2005.00027.x.
Two isolates of Paenibacillus validus (DSM ID617 and ID618) stimulated growth of the arbuscular mycorrhizal fungus Glomus intraradices Sy167 up to the formation of fertile spores, which recolonize carrot roots. Thus, the fungus was capable of completing its life cycle in the absence of plant roots, but relied instead on the simultaneous growth of bacteria. The supernatant of a mixed batch culture of the two P. validus isolates contained raffinose and another, unidentified trisaccharide. Among the oligosaccharides tested, raffinose was most effective in stimulating hyphal mass formation on plates but could not promote growth to produce fertile spores. A suppressive subtractive hybridization library followed by reverse Northern analyses indicated that several genes with products involved in signal transduction are differentially expressed in G. intraradices SY 167 when grown in coculture with P. validus (DSM 3037). The present investigation, while likely representing a significant step forward in understanding the arbuscular mycorrhizal fungus symbioses, also confirms that its optimal establishing and functioning might rely on many, as yet unidentified factors.
两株有效芽孢杆菌（DSM ID617和ID618）刺激了丛枝菌根真菌根内球囊霉Sy167的生长，直至形成可育孢子，这些孢子重新定殖在胡萝卜根上。因此，该真菌能够在没有植物根系的情况下完成其生命周期，而是依赖于细菌的同时生长。这两株有效芽孢杆菌混合分批培养物的上清液中含有棉子糖和另一种未鉴定的三糖。在所测试的寡糖中，棉子糖在刺激平板上的菌丝体形成方面最有效，但不能促进生长以产生可育孢子。通过抑制性消减杂交文库和反向Northern分析表明，当与有效芽孢杆菌（DSM 3037）共培养时，根内球囊霉SY 167中几个与信号转导相关产物的基因表达存在差异。本研究虽然可能代表了在理解丛枝菌根真菌共生关系方面向前迈出的重要一步，但也证实了其最佳建立和功能可能依赖于许多尚未确定的因素。
