PDF(Pubmed)
Abstract：
Volatile organic compounds (VOCs) play an important role in the communication among organisms, including plants, beneficial or pathogenic microbes, and pests. In vitro, we observed that the growth of seven out of eight Basidiomycete species tested was inhibited by the VOCs of the biocontrol agent Pseudomonas protegens strain CHA0. In the Ascomycota phylum, only some species were sensitive (e.g., Sclerotinia sclerotiorum, Botrytis cinerea, etc.) but others were resistant (e.g., Fusarium oxysporum f. sp. cubense, Verticillium dahliae, etc.). We further discovered that CHA0 as well as other ten beneficial or phytopathogenic bacterial strains were all able to inhibit Heterobasidion abietinum, which was used in this research as a model species. Moreover, such an inhibition occurred only when bacteria grew on media containing digested proteins like peptone or tryptone (e.g., Luria-Bertani agar or LBA). Also, the inhibition co-occurred with a pH increase of the agar medium where the fungus grew. Therefore, biogenic ammonia originating from protein degradation by bacteria was hypothesized to play a major role in fungus inhibition. Indeed, when tested as a synthetic compound, it was highly toxic to H. abietinum (effective concentration 50% or EC50 = 1.18 M; minimum inhibitory concentration or MIC = 2.14 M). Using gas chromatography coupled to mass spectrometry (GC/MS), eight VOCs were found specifically emitted by CHA0 grown on LBA compared to the bacterium grown on potato dextrose agar (PDA). Among them, two compounds were even more toxic than ammonia against H. abietinum: dimethyl trisulfide had EC50 = 0.02 M and MIC = 0.2 M, and 2-ethylhexanol had EC50 = 0.33 M and MIC = 0.77 M. The fungus growth inhibition was the result of severe cellular and sub-cellular alterations of hyphae occurring as early as 15 min of exposure to VOCs, as evidenced by transmission and scanning electron microscopy observations. Transcriptome reprogramming of H. abietinum induced by CHA0\'s VOCs pointed out that detrimental effects occurred on ribosomes and protein synthesis while the cells tried to react by activating defense mechanisms, which required a lot of energy diverted from the growth and development (fitness cost).
摘要：
挥发性有机化合物(VOCs)在生物体间的交流中起着重要作用,包括植物,有益或致病微生物，和害虫。体外，我们观察到，测试的八种担子菌中的七种的生长被生物防治剂假单胞菌蛋白菌株CHA0的VOC抑制。在子囊门中，只有一些物种是敏感的(例如，菌核病,灰葡萄孢菌,等。)，但其他人具有抗性(例如，尖孢镰刀菌f.sp.立方体，大丽花黄萎病菌,等。).我们进一步发现，CHA0以及其他十种有益的或植物病原性的细菌菌株都能够抑制异位菌。在这项研究中被用作模型物种。此外，只有当细菌在含有蛋白胨或胰蛋白胨等消化蛋白的培养基上生长时，这种抑制作用才会发生(例如，Luria-Bertani琼脂或LBA）。此外，抑制与真菌生长的琼脂培养基的pH增加同时发生。因此,据推测，源自细菌降解蛋白质的生物氨在真菌抑制中起主要作用。的确,当作为合成化合物测试时，它对H.abietinum具有高度毒性（有效浓度50％或EC50=1.18M；最低抑制浓度或MIC=2.14M）。使用气相色谱与质谱联用（GC/MS），与在马铃薯葡萄糖琼脂（PDA）上生长的细菌相比，在LBA上生长的CHA0发现了8种VOC。其中,两种化合物对H.abietinum的毒性甚至比氨更大：二甲基三硫的EC50=0.02M和MIC=0.2M，和2-乙基己醇的EC50=0.33M和MIC=0.77M。真菌生长抑制是菌丝的严重细胞和亚细胞改变的结果，早在暴露于VOC15分钟时就发生了，透射和扫描电子显微镜观察证明。CHA0的VOCs诱导的阿比菌的转录组重编程指出，当细胞试图通过激活防御机制进行反应时，对核糖体和蛋白质合成产生不利影响。这需要从成长和发展中转移大量的能量(健身成本)。
