N status might act as a key signal regulating and integrating
various metabolic processes that occur during association
with diazotrophic bacteria. Besides directly providing ammonium
to plants, the associative and endophytic diazotrophic
bacteria enhance N uptake of inoculated plants, an effect
that could be important for enhancing NUE. Nevertheless,
high N levels inside plants seem to signal a feedback control,
negatively regulating BNF and bacterial colonization.
High N in soil could contribute to an increase in N levels in
plants, activating this negative feedback control. Therefore, a
clear understanding of the mechanisms in N regulation during
plant interaction with associative and endophytic diazotrophic
bacteria could provide tools to maximize the benefits
for crop production