Plant immunity: metabolomic characterization of pea and faba bean root exudates
Résumé
Legume crops are interesting for both the nutritional quality of their seeds and the
natural nitrogen fertilization of soils. Pea remains the major legume crop in France, even if its
production declines due to root rot caused by the pathogen Aphanomyces euteiches. The
infection can result in yield losses of up to 80% in peas [1] while faba bean cultivars are less
susceptible to this pathogen. There is no effective protection against this disease other than
crop rotation. To develop new control methods, it is thus necessary to better understand the
infectious process and the establishment of plant defenses. Given that a recent study
revealed that faba root exudates alter pea root colonization [2], our objective is to compare
the compounds emitted by the pea and faba roots using an untargeted metabolomics
approach.
Pea and faba seedlings were hydroponically grown, and root exudates were harvested
and analyzed by NMR. The obtained exudation profiles are characteristic of each species
even if there are variations within the same variety, in particular regarding compound
concentrations. Spectra annotation shows an enrichment of faba exudates in sugars, and
peas in amino acids. However, many of the compositional differences noted between pea
and faba exudates correspond to unidentified metabolites. Additional analyzes are necessary
to identify which metabolites provide faba root protection against A. euteiches, and to
consider the development of pea resistance.
References
1. Gaulin et al. (2007) Molecular Plant Pathology 8(5):539-548.
2. Laloum et al. (2021) Plant Science 312:111032.