Rhizospehric microorganisms tightly interact with their host plant by influencing
her growth and modulating her metabolome. As proof of a concept, the effect of the
extracellular medium and bacteria cells homogenate of five strain suspensions belonging
to Chitinophaga sp., Xanthomonas sp., Pseudomonas sp., Allorhizobium sp., Micromonospora sp. were tested on in vitro callus culture of Alkanna tinctoria (L.) Tausch. For rapid discrimination of callus metabolome modification, a High-Performance
Thin-Layer Chromatography (HPTLC) image-fingerprints analysis method was developed.
As a result of the multivariate analysis, bacteria cells homogenate and extracellular
medium induced the production of different kinds of secondary metabolites. Chitinophaga sp. and Allorhizobium sp. bacteria extracellular medium were revealed as promising
“metabolome modulator” since the chemical fingerprint is close to the one elicited
by phytohormonal elicitor: Methyl jasmonate. Crucial markers were then identified
using a TLC-MS interface combined with UHPLC-MS analysis. In parallel, HTPLC-DPPH
effect-directed analysis was performed and demonstrated the production of new antioxidant
metabolites after 30 days of coculture. The developed HPTLC-based untargeted metabolomic
method has proved to be a robust approach to monitor interactions among bacteria endophytes
and their host plant. The results confirmed that endophytes play an essential role
in the biotransformation/induction of compounds of interest.
This work has been financed by the EU H2020-ITN-MICROMETABOLITE project (Grant N°721635)
