Influence of pea genotype on root associated fluorescent pseudomonads, impact on plant iron nutrition

International audience

إنجليزي. Pea has a high potential in agroecology because of its ability to fix atmospheric nitrogen and for Humannutrition due to the high amino-acids content of its seeds. However, pea can suffer from a susceptibility toiron deficiency in calcareous soils as expressed by chlorosis symptoms. Previous studies have shown thatsiderophores of model strains of fluorescent pseudomonads (fp), pyoverdines, promote iron nutrition ofarabidopsis and tobacco. We hypothesized that susceptibility to iron deficiency of pea is at least partly dueto its ability to select fluorescent pseudomonad that promote differentially plant nutrition thanks to theirsiderophores.To identify siderophores potentially beneficial for plant nutrition and, in fine, identify plantgenotypes 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 andtheir corresponding pyoverdines and in return ii) the impact of representatives of these pyoverdines onplant iron nutrition.Two distinct pea cultivars chosen for their contrasting capabilities to overcome irondeficiency (S, susceptible and T, tolerant) were grown in a calcareous soil. fp associated with roots of bothplant genotypes and corresponding pyoverdines were compared. In return, representative pyoverdinessynthesized by fp associated to S and T were compared for their effect on the transcription of genesinvolved in plant iron uptake and homeostasis (rt-qPCR) and their impact on plant iron content andionome (HRICP-MS).Differences were observed in the culturable populations of fp associated with S andT. Study of the effect of corresponding predominant pyoverdines showed that they impact differentiallyplant gene expression and ionome. The results obtained evidence a plant-genotype dependent effect ofmicrobial siderophores on plant nutrition. Further studies are in progress to unravel the mechanismsimplied.