Fig. 7: ¹⁵N isotope labeling experiment with maize inbred line 93-63 and different bacterial inoculants.

a ¹⁵N-dilution experiments with maize inbred line 93-63 and different bacterial inoculants. 0.5 mM ¹⁵NO₃⁻ was added at the time of inoculation. Dry weight (DW) of maize after 12 days inoculation of maize with either wild type or mutant strains of K. oxytoca. The means and SEMs were calculated. n = 5–6 biologically independent samples. Statistical significance is indicated as **P ≤ 0.01 analyzed using one-way ANOVA with Student’s t-test. NS, non-significant. P values from left to right: 0.00088 (KoΔnif vs Ko424) and 0.00071 (Ko vs Ko424). b, c Direct ¹⁵N incorporation into maize from ¹⁵N₂. b Schematic diagram of the maize hydroponics system for ¹⁵N isotopic analysis. c Determination of fractional enrichment of the ¹⁵N isotope into pheophytin from maize inoculated with KoΔnif, Ko and Ko424. 50% of the co-culture gas was displaced with ¹⁵N₂ gas and the final oxygen concentration in the gas mixture was 20%. 1% CO₂ was added daily. The results were subtracted from the fractional ¹⁵N isotope enrichment of the uninoculated control. Asterisks indicate a statistically significant difference relative to Ko. The means and SEMs were calculated. n = 6 biologically independent samples. Statistical significance is indicated as **P ≤ 0.01 analyzed using one-way ANOVA with Student’s t-test. NS, non-significant. Two-sided P value: 0.0000036 (Ko vs Ko424). Source data are provided as a Source Data file.