Date Published: March 30, 2017
Publisher: Public Library of Science
Author(s): Adam Ossowicki, Sylwia Jafra, Paolina Garbeva, Rita Grosch.
Soil and rhizosphere bacteria produce an array of secondary metabolites including a wide range of volatile organic compounds (VOCs). These compounds play an important role in the long-distance interactions and communication between (micro)organisms. Furthermore, bacterial VOCs are involved in plant pathogens inhibition and induction of soil fungistasis and suppressivenes. In the present study, we analysed the volatile blend emitted by the rhizospheric isolate Pseudomonas donghuensis P482 and evaluated the volatile effect on the plant pathogenic fungi and bacteria as well as one oomycete. Moreover, we investigated the role of the GacS/GacA system on VOCs production in P. donghuensis P482. The results obtained demonstrated that VOCs emitted by P. donghuensis P482 have strong antifungal and antioomycete, but not antibacterial activity. The production of certain volatiles such as dimethyl sulfide, S-methyl thioacetate, methyl thiocyanate, dimethyl trisulfide, 1-undecan and HCN is depended on the GacS/GacA two-component regulatory system. Apparently, these compounds play an important role in the pathogens suppression as the gacA mutant entirely lost the ability to inhibit via volatiles the growth of tested plant pathogens.
Volatile organic compounds (VOCs) are commonly produced by all organisms including bacteria, fungi and plants. They are low molecular mass molecules (<300 Da) able to penetrate soil and rhizosphere. VOCs synthesized by soil and plant-associated microorganisms have been shown to suppress the growth of plant pathogenic microorganisms indicating that these compounds could be one of the important mechanisms for biological control of plant diseases [1,2]. Soil and rhizosphere bacteria produce a large amount of secondary metabolites, which have many different physiochemical and biological properties. Beside well documented, soluble antimicrobial compounds bacteria emit a wide range of VOCs that hold a strong inhibitory capacity [5,9,20,39]. In this study, we attempted to determine the VOCs emitted by the rhizospheric isolate P. donghuensis P482, their antimicrobial activity and the role of the two-component GacS/GacA regulatory system in VOCs production. Source: http://doi.org/10.1371/journal.pone.0174362