Bacterial rhamnolipids are novel MAMPs conferring resistance to Botrytis cinerea in grapevine

Abstract

Rhamnolipids produced by the bacteria Pseudomonas aeruginosa are known as very efficient biosurfactant molecules. They are used for a wide range of industrial applications, especially in food, cosmetics and pharmaceutical formulations as well as in bioremediation of pollutants. In this paper, the role of rhamnolipids as novel molecules triggering defence responses and protection against the fungus Botrytis cinerea in grapevine is presented. The effect of rhamnolipids was assessed in grapevine using cell suspension cultures and vitro-plantlets. Ca 2+ influx, mitogenactivated protein kinase activation and reactive oxygen species production form part of early signalling events leading from perception of rhamnolipids to the induction of plant defences that include expression of a wide range of defence genes and a hypersensitive response (HR)-like response. In addition, rhamnolipids potentiated defence responses induced by the chitosan elicitor and by the culture filtrate of B. cinerea. We also demonstrated that rhamnolipids have direct antifungal properties by inhibiting spore germination and mycelium growth of B. cinerea. Ultimately, rhamnolipids efficiently protected grapevine against the fungus.We propose that rhamnolipids are acting as microbeassociated molecular patterns (MAMPs) in grapevine and that the combination of rhamnolipid effects could participate in grapevine protection against grey mould disease.

Rhamnolipids Elicit Defense Responses and Induce Disease Resistance against Biotrophic, Hemibiotrophic, and Necrotrophic Pathogens That Require Different Signaling Pathways in Arabidopsis and Highlight a Central Role for Salicylic Acid

“…These results suggest that high concentrations of RLs may trigger a hypersensitive response (HR)-like response as previously described for grapevine (Varnier et al, 2009).…”

“…PR-1 is well known as a SAdependent defense gene marker (Lebel et al, 1998;Vlot et al, 2009) whereas PDF1.2 expression is regulated by JA/ET (Penninckx et al, 1996;Penninckx et al, 1998), and PR-4 expression is dependent on ET (Lawton et al, 1994). We used two concentrations of RLs (0.2 and 1 mg mL 21 ) to compare the responses induced by low and strong RLs stimuli (Varnier et al, 2009). PR-1 expression was induced at 6 h in response to both concentrations of RLs and peaked at 24 h post treatment (hpt; Fig.…”

“…RLs are potent stimulators of animal immunity (Vatsa et al, 2010). They have recently been shown to elicit plant defense responses and to induce resistance against B. cinerea in grapevine (Vitis vinifera; Varnier et al, 2009). They also participate to biocontrol activity of the plant beneficial bacteria Pseudomonas aeruginosa PNA1 against oomycetes (Perneel et al, 2008).…”

Lipids as Markers of Induced Resistance in Wheat: A Biochemical and Molecular Approach

“…In grapevine plantlets, rhamnolipids induced for lox gene expression a 7-fold increase 24 h after immersion in the rhamnolipids solution [72]. In wheat, transcripts of WCI-2 (Wheat Chemically Induced gene) gene, which encodes a lipoxygenase, accumulated quickly in response to MeJA, SA and BTH treatments (from 2 h to 24h for MeJA, and from 4h and to 20 h for the other elicitors); however, SA induced this gene's expression to a lesser extent than the other two compounds [73].…”

Electrolytic treatment and biosurfactants applied to the conservation of Eugenia uniflora fruit

“…Rhamnolipids, which are a type of surfactant, can further be used for the protection of vines against attack by Botrytis cinerea, because they inhibit spore germination and mycelial growth (Varnier et al, 2009). Vatsa et al (2010) reports the antifungal rhamnolipid activity against various fungal plants pathogens such as Botrytis sp, Rhizoctonia sp, Pythium sp, Phytophtora sp.…”