The use of fertilizers and pesticides to control plant diseases is widespread
in intensive farming causing adverse effects together with the development of
antimicrobial resistance pathogens. As the virulence of many Gram-negative
phytopathogens is controlled by N-acyl-
homoserine
lactones (AHLs), the
enzymatic disruption of this type of quorum-sensing
(QS) signal molecules,
mechanism known as quorum quenching (QQ), has been proposed as a
promising alternative antivirulence therapy. In this study, a novel strain of
Bacillus toyonensis isolated from the halophyte plant Arthrocaulon sp. exhibited
numerous traits associated with plant growth promotion (PGP) and
degraded a broad range of AHLs. Three lactonases and an acylase enzymes
were identified in the bacterial genome and verified in vitro. The AHL-degrading
activity of strain AA1EC1 significantly attenuated the virulence of
relevant phytopathogens causing reduction of soft rot symptoms on potato
and carrots. In vivo assays showed that strain AA1EC1 significantly increased
plant length, stem width, root and aerial dry weights and total weight of tomato
and protected plants against Pseudomonas syringae pv. tomato. To our
knowledge, this is the first report to demonstrate PGP and QQ activities in
the species B. toyonensis that make this strain as a promising phytostimulant
and biocontrol agent.Spanish Ministry
for Science and Innovation/Agencia Estatal de
Investigación 10.13039/501100011033ESF
Investing in your future (Grant: RYC2019- 026481-I)Spanish Ministry for Science and Innovation/Agencia
Estatal de Investigación 10.13039/501100011033
(Grant: PID2019-106704RB-100)Consejería de
Universidad, Investigación e Innovación de la Junta de
AndalucíaERDF A way of making Europe (Grant:
B-AGR-222-UGR20