2-Tridecanone impacts surface-associated bacterial behaviours and hinders plant-bacteria interactions

Area of Science:

• Microbiology
• Bacterial Physiology
• Plant-Microbe Interactions

Background:

• Surface motility and biofilm formation are key bacterial virulence factors regulated by chemical signals.
• In Sinorhizobium meliloti, a deficiency in long-chain fatty acyl-coenzyme A synthetase (FadD) impairs root colonization and alters motility and biofilm development.

Purpose of the Study:

• To investigate the molecular mechanisms underlying the altered phenotypes in a Sinorhizobium meliloti fadD mutant.
• To identify the role of 2-tridecanone (2-TDC) as an infochemical in bacterial behavior and plant interactions.

Main Methods:

• Analysis of lipid extracts and volatiles from wild-type and fadD mutant strains.
• Application of purified 2-TDC to wild-type bacteria and pathogenic strains.
• Transcriptomic analysis to identify gene expression changes induced by 2-TDC.
• Assessment of effects on bacterial motility, biofilm formation, and plant symbiotic/pathogenic interactions.

Main Results:

• The fadD mutant accumulates 2-tridecanone (2-TDC), a methylketone.
• Exogenous 2-TDC application to wild-type S. meliloti mimicked the fadD mutant's enhanced flagella-independent surface motility and defective biofilm formation.
• 2-TDC modulated the expression of iron uptake, redox, and stress-related genes.
• 2-TDC negatively impacted nodulation in alfalfa and exacerbated tomato bacterial speck disease, while also affecting motility and biofilm formation in other pathogenic bacteria.

Conclusions:

• 2-Tridecanone (2-TDC) acts as a signaling molecule influencing bacterial surface motility, biofilm formation, and gene expression.
• 2-TDC interferes with plant-microbe interactions, hindering symbiotic colonization and exacerbating plant diseases.
• This study reveals a novel role for methylketones as infochemicals affecting bacterial behavior and host colonization.