Coordinated regulation of carbon and nitrogen assimilation confers drought tolerance in maize (Zea mays L.)

(A)LY66 has greater drought tolerance and recovery than LY99 through coordinating regulation of C and N assimilation. Up- (red) and down-regulated (green) genes encoding C/N metabolism-responsive enzymes in LY66 when compared to LY99 under drought stress. (B) Auxin might participate in coordinating regulation of C and N assimilation and drought tolerance. Rubp: Ribulose-1,5-disphosphate; PGA: 3-phosphoglycerate; GAP: Glyceraldehyde 3-phosphate; TP: Triose phosphate; ADPG: Adenosine diphosphate glucose; Gln: Glutamine; Glu: Glutamate; NO3−: Nitrate; NO2−: Nitrite; NH4+: Ammonia; LHCa: PS-I light harvesting complex subunit; LHCb: PS-II light harvesting complex subunit; PSBA: Chlorophyll binding protein D1; PSBD: Chlorophyll binding protein D2; Rubp: Ribulose bisphosphate carboxylase; GAP: Glyceraldehyde phosphate dehydrogenase; SPS: Sucrose phosphate synthase; AGP: ADP glucose pyrophosphorylase; GBSS: Granule-bound starch synthase; SBE: Starch branching enzyme; SS: Starch synthase; INV: Invertase; SuSy: Sucrose synthase; NR: Nitrate reductase; NiR: Nitrite reductase; AMT: Ammonium transporter protein; GS: Glutamine synthetase; GDH: Glutamate dehydrogenase. [Display omitted] •LY66 exhibits greater drought tolerance than LY99.•Coordinated regulation of C and N assimilation confers drought tolerance in maize.•Coordinated C and N assimilation under drought stress is possibly involved in phytohormone signaling pathways Drought is a major limiting factor affecting crop productivity. To gain a comprehensive understanding of transcriptomic reprogramming under drought stress in maize (Zea mays L.), we performed physiological and transcriptomic analysis of leaf tissues of two maize cultivars, LY66 and LY99, subjected to a progressively severe drought and subsequent recovery. LY66 exhibited greater drought tolerance and recovery than LY99. RNA-Seq analysis showed that differentially expressed genes mainly enriched in pathways involved in carbon (C) and nitrogen (N) metabolism, and plant hormone signal transduction. As judged from RNA-Seq data, enzyme activity, and metabolite contents, LY66 maintained a higher relatively stable C and N metabolism than LY99, which were related to higher photosynthesis and sucrose biosynthesis capacity, higher N assimilation and protein biosynthesis capacity under drought stress, respectively. Interestingly, the expression of several genes encoding key enzymes involved in auxin biosynthesis and signaling were activated to higher levels in