Integrative Strategies to Enhance Phosphorus Use Efficiency in Maize: Plant Breeding, Soil Dynamics and Plant–Microbe Interactions Under Phosphorus Stress

Phosphorus (P) is an essential macronutrient for plant growth and a major limiting factor for crop productivity, especially in tropical soils characterized by low P availability and high fixation capacity. The strong dependence of modern agriculture on non-renewable phosphate fertilizers, combined with their low use efficiency, raises economic and environmental concerns and reinforces the need to improve phosphorus use efficiency (PUE) in maize. PUE is a complex trait governed by integrated morphophysiological, biochemical, and molecular mechanisms related to phosphorus acquisition, internal remobilization, metabolic reprogramming, and root system plasticity. Recent advances using omics-based approaches have substantially expanded the understanding of these mechanisms, revealing coordinated regulation of carbon and energy metabolism, phosphatase activity, redox balance, and root meristem dynamics under P-limiting conditions. In parallel, increasing evidence demonstrates the important role of phosphate-solubilizing and plant growth-promoting bacteria in enhancing P availability through organic acid secretion, enzymatic mineralization of organic P forms, and modulation of root architecture. However, despite these advances, the genetic basis of plant responsiveness to beneficial bacteria and the interaction between host genotype and microbial activity remain poorly explored. This review integrates current knowledge on phosphorus dynamics in the soil–plant system, the genetic control of PUE in maize, and the contribution of beneficial bacteria, highlighting the importance of combining classical breeding, molecular approaches, and microbial strategies to accelerate the development of maize cultivars with improved phosphorus efficiency and reduced fertilizer dependency.