Effect of volatile compounds produced by endophytic bacteria on virulence traits of grapevine crown gall pathogen, Agrobacterium tumefaciens

Abstract

The volatile organic compounds (VOCs) produced by endophytic bacteria have a significant role in the control of phytopathogens. In this research, the VOCs produced by endophytic bacteria including Serratia sp. Ba10, Pantoea sp. Sa14, Enterobacter sp. Ou80, Pseudomonas sp. Ou22, Pseudomonas sp. Sn48 and Pseudomonas sp. Ba35, which were previously isolated from healthy domesticated and wild-growing grapevine were evaluated in terms of their effects on the virulence traits of Agrobacterium tumefaciens Gh1, the causal agent of crown gall disease. Based on the gas chromatography–mass spectrometry analysis, 16, 15, 14, 7, 16, and 15 VOCs have been identified with high quality in strains of Ba10, Sa14, Ou80, Ou22, Sn48, and Ba35, respectively. All endophytic bacteria produced VOCs that significantly reduced crown gall symptoms and inhibited the populations of A. tumefaciens Gh1 at different levels. Moreover, scanning electron microscopy analysis revealed various morphological abnormalities in the A. tumefaciens cells exposed to the VOCs produced by Ba35, Ou80, and Sn48 strains. The VOCs significantly reduced swarming-, swimming-, twitching motility and biofilm formation by A. tumefaciens Gh1. Our results revealed that VOCs could reduce the attachment of A. tumefaciens Gh1 cells to root tissues of grapevine cultivars Rashe and Bidane sefid, as well as chemotaxis motility towards root extract of both cultivars. Based on our results, it was shown that the antibacterial VOCs produced by endophytic bacteria investigated in the current study can manage crown gall disease and increase our knowledge on the role of VOCs in microbial interactions.

Biocontrol activity and potential mechanism of volatile organic compounds from Aspergillus niger strain La2 against pear Valsa canker

“…Some studies have shown that VOCs released from endophytes can be as biocontrol agents to inhibit the growth of pathogens. 28,29 Strobel et al found that VOCs produced by Muscodor albus had strong antimicrobial activity and could be used to control soil-borne diseases. 30 Zhang et al found that VOCs released by Pseudomonas chlororaphis subsp.…”

“…Some studies have shown that VOCs released from endophytes can be as biocontrol agents to inhibit the growth of pathogens 28,29 . Strobel et al .…”

Use of beneficial bacterial endophytes: A practical strategy to achieve sustainable agriculture

“…Volatile organic compounds are signaling substances that intermediate the interaction between a plant and microbes. Volatile organic compounds are very important, as they help in the inhibition of plant-pathogen growth and induce systematic resistance in a host plant [116] , [121] . Like other bacteria, endophytic bacteria may produce volatile organic compounds such as 2,3-butanediol, acetoin, 2-hexanone, sulfur-containing compounds, 2-heptonone, 3-methybutan-1-ol and dodacanal.…”

Volatile organic compounds produced by Pseudomonas chlororaphis subsp. aurantiaca ST-TJ4 antagonize the cherry blossom crown gall pathogen Agrobacterium tumefaciens

“…These features that could be useful in biological control have aroused great interest in VOCs released by microorganisms. Many studies on VOCs produced by bacteria have shown that they inhibit the growth of plant pathogens [12][13][14][15][16] . VOCs produced by Pseudomonas uorescens WR-1 can inhibit the growth of Ralstonia solanacearum, the pathogen that causes tomato bacterial wilt, and reduce its pathogenicity [16] .…”

“…Recently, studies have reported that Serratia plymuthica, Pseudomonas uorescens and their VOCs have antibacterial activity against A. tumefaciens [18] . In addition, VOCs produced by endophytic bacteria have been suggested to signi cantly reduce the occurrence of grape tumors and cause abnormal morphology of A. tumefaciens cells [14] . These results proved that VOCs produced by biocontrol bacteria play an important role in antagonizing pathogens and interacting with host plants and provided a new source of compounds with antibiotic and plant growth promotion activities.…”