Influence of pea genotype on root associated fluorescent pseudomonads, impact on plant iron nutrition
Résumé
Pea has a high potential in agroecology because of its ability to fix atmospheric nitrogen and for Human
nutrition due to the high amino-acids content of its seeds. However, pea can suffer from a susceptibility to
iron deficiency in calcareous soils as expressed by chlorosis symptoms. Previous studies have shown that
siderophores of model strains of fluorescent pseudomonads (fp), pyoverdines, promote iron nutrition of
arabidopsis and tobacco. We hypothesized that susceptibility to iron deficiency of pea is at least partly due
to its ability to select fluorescent pseudomonad that promote differentially plant nutrition thanks to their
siderophores.To identify siderophores potentially beneficial for plant nutrition and, in fine, identify plant
genotypes capable of making the most of the rhizosphere microbiota, our strategy is to evaluate (i)
influence of the pea genotype on diversity of the rhizosphere microbiota with a special focus on fp and
their corresponding pyoverdines and in return ii) the impact of representatives of these pyoverdines on
plant iron nutrition.Two distinct pea cultivars chosen for their contrasting capabilities to overcome iron
deficiency (S, susceptible and T, tolerant) were grown in a calcareous soil. fp associated with roots of both
plant genotypes and corresponding pyoverdines were compared. In return, representative pyoverdines
synthesized by fp associated to S and T were compared for their effect on the transcription of genes
involved in plant iron uptake and homeostasis (rt-qPCR) and their impact on plant iron content and
ionome (HRICP-MS).Differences were observed in the culturable populations of fp associated with S and
T. Study of the effect of corresponding predominant pyoverdines showed that they impact differentially
plant gene expression and ionome. The results obtained evidence a plant-genotype dependent effect of
microbial siderophores on plant nutrition. Further studies are in progress to unravel the mechanisms
implied.