Agroécologie, INRAE, Institut Agro, Université de Bourgogne - Université de Bourgogne Franche-Comté, Dijon, France Microbiota, with their consortia of genomes, extend the genetic repertoires of host plants to form ‘extended genotypes’, resulting in extended host phenotypes. Trecently, the term ‘holobiont’, which encompasses the host plant plus its associated microbiota, has been proposedHow environmental properties impact both the plant and microbial components of the holobiont, and its phenotype, still remain to be explored. We addressed this question by testing the impact of different abiotic conditions (drought stress and soil pH) on plant and microbial phenotypes in relation to iron. Iron bioavailability is essential to plant and microbial physiology, and depends on soil aeration and pH. Two pea cultivars, showing different tolerance to iron chlorosis, were cultivated in two soils with different pH and textures. Aeration of these soils was modified by submitting them to three different matric potentials (saturated water SW, field capacity FC and wilting point WP). Pea phenotypes were characterized by measuring their biomass and ionomic content. Microbial phenotypes were characterized by assessing their ability to synthesize siderophores and their susceptibility to iron stress. Plant biomass and iron content were lower in both soils when they were submitted to drought stress (WP), likely to increased soil aeration and thus iron oxidation leading to low bioavailability. Accordingly, the occurrence of bacterial isolates producing siderophores was higher in these iron stress conditions. This bioavailability is known to be even more decreased in soils with higher pH, and isolates were indeed further less susceptible to iron deficiency. In conclusion, microbial populations producing siderophores were more represented in drought conditions, corresponding to higher aeration, whatever the soil was. This suggests that drought stress has a similar impact on both the plant and microbial phenotypes whatever the soil type is.