Plant interactions with arbuscular mycorrhizal fungi have long attracted interest for their potential to promote more efficient use of mineral resources in agriculture. Their widespread use, however, remains limited by understanding of the processes that determine the outcome of the symbiosis. In this study, variation in growth response to mycorrhizal inoculation was characterized in a panel of diverse maize lines. A panel of thirty maize lines was evaluated with and without inoculation with arbuscular mycorrhizal fungi. The line Oh43 was identified to show superior response and, along with five other reference lines, was characterized in greater detail in a split-compartment system, using 33P to quantify mycorrhizal phosphorus uptake. Changes in relative growth between non-inoculated and inoculated plants indicated variation in host capacity to profit from the symbiosis. Shoot phosphate content, abundance of intra-radical and root-external fungal structures, mycorrhizal phosphorus uptake, and accumulation of transcripts encoding plant PHT1 family phosphate transporters varied among lines. Larger growth responses in Oh43 were correlated with extensive development of root-external hyphae, accumulation of specific Pht1 transcripts and a high level of mycorrhizal phosphorus uptake. The data indicate that host genetic factors influence fungal growth strategy with an impact on plant performance.