Interactions between <em>Pisum sativum</em> & pseudomonads, consequences on plant iron nutrition and growth and immunity

Abstract

National audiencePea has a high potential in agroecology, however, it may suffer from a susceptibility to iron deficiency in calcareous soils. This susceptibility varies depending on cultivars. Pseudomonad siderophores, pyoverdines (pvd), were shown to promote iron nutrition in Arabidopsis and tobacco. The hypothesis was therefore raised that variation in iron susceptibility between pea cultivars could be related to differences in their ability to recruit fluorescent pseudomonads (fp) contributing to siderophore-mediated iron nutrition. Our aims were to compare i) the impact of a susceptible (S) and a tolerant (T) cultivar of pea on fp biodiversity with a focus on their pvd, and in return ii) the impact of the corresponding bacteria and pvd on pea iron growth and nutrition. fp associated with roots of S & T and corresponding pvd were compared. In return, representative pvd were tested for their impact on plant growth, iron content and ionome (HRICP-MS). Differences recorded between fp associated with T and S roots were related to i) their low susceptibility to Fe deficiency and ii) their pvd types as characterized by isoelectrofocalisation. Representatives of major pvd types impacted differently S & T iron content, plant ionome and growth. The results obtained support the principle of an extended phenotype in which associated bacteria contribute to plant nutrition, showing the importance to consider root microbiota to develop strategies aiming at overcoming iron susceptibility in pea