Root-associated microbiome of maize genotypes with contrasting P use efficiency

Marginal soil fertility, soil acidity, aluminum toxicity, and a generalized low level of available nutrients, especially phosphorus (P), are major limiting factors to maize production in highly weathered Oxisols. Plants have evolved several strategies to improve P acquisition, including the ability to associate with soil microorganisms that potentially enhance P uptake and plant nutrition. We investigated the impact of two P soil levels and plant genotypes with contrasting P use efficiency on the composition of bacterial and fungal communities in root and rhizosphere of maize. We found that significant fractions of bacterial and fungal diversities could be attributed to host genotype, but in general, the P soil level was the major driver of microbiome distribution and composition for both plant compartments (rhizosphere and directly root associated). Slow-growing bacterial taxa were more abundant in the low P soil whereas fast-growing taxa were enriched in high P soil. Considering microorganisms involved in P cycling, we observed a positive effect of low P on arbuscular mycorrhizal fungi abundance especially inside the roots. On the other hand, our results did not support selection for P-solubilizing bacteria under reduced P input. Taken together, our results expand knowledge of which microbial communities are adapted to P-stressed soil, suggest that maize genotypes may help select beneficial microbiomes, and potentially lead to microbial isolates for host paired inoculants for improving agricultural production.