Exploring nitrogen use efficiency in Algerian maize germplasm by agronomic and transcriptomic approaches

Abstract Nitrogen use efficiency (NUE) is a key trait for sustainable maize production, balancing high yield performance with reduced environmental impacts associated with nitrogen (N) fertilization. This study assessed the agronomic, physiological, and molecular responses of diverse maize populations under different nitrogen input levels. Nitrogen availability significantly affected grain yield, biomass accumulation, total nitrogen uptake, and nitrogen use efficiency, with significant genotype × nitrogen interactions revealing contrasting adaptive responses among maize populations. In particular, population P13 emerged as a promising candidate, exhibiting stable grain yield under low N conditions, high N uptake efficiency, and superior photosynthetic performance, suggesting strong adaptation to N stress when compared to P11, low efficiency. Gene ontology (GO) enrichment analysis revealed significant modulation of genes involved in ion transport, photosynthesis, and stress responses. Notably, hub genes within the turquoise module of the co-expression network were positively correlated with NUE and included ZmNRT2.7, involved in vacuolar nitrate export, and ZmNDH-B3, contributing to photosynthetic electron transport. The strong expression of these genes in P13 suggests a molecular basis for its superior NUE. These findings underscore the potential of integrating phenotypic screening and transcriptomic approaches to uncover key mechanisms underlying NUE for breeding programs with enhanced nitrogen efficiency, ensuring both high productivity and environmental sustainability in low-input agricultural systems.