Identification of metabolic and protein markers representative of the impact of mild nitrogen deficit on agronomic performance of maize hybrids

Background A better understanding of the physiological response of silage maize to a mild reduction in nitrogen(N) fertilization and the identification of predictive biochemical markers of N utilization efficiency could contribute to limit the detrimental effect of the overuse of N inputs. Results To identify predictive biochemical markers of nitrogen (N) utilization and metabolism of silage maize in relation to growth and productivity, a metabolomic and a proteomic approach were combined. These analyses were performed on young leaves of a core panel of 29 European genetically diverse dent hybrids cultivated in the field under non-limiting and reduced N fertilization conditions in order to identify such predictive markers at an early stage of plant development. Metabolome and proteome data were analyzed either individually or in an integrated manner together with eco-physiological, developmental and yield-related traits. These analyses allowed to depict the physiology underlying plant response to the mild N deficit often occurring when maize is grown under agronomic conditions. Moreover, the genetic diversity of the 29 hybrids was exploited to identify common N-responsive metabolites and protein that could be used as predictive markers to monitor N fertilization and to identify silage maize hybrids representing possible ideotypes that exhibit improved agronomic performance when N fertilization is reduced. Conclusion Among the N-responsive metabolites and proteins identified, a cytosolic NADP-dependent malic enzyme and four metabolite signatures stand out as promising markers that could be used for both breeding and agronomic purposes.