PLANT PHOSPHORUS USE EFFICIENCY IN ACID TROPICAL SOIL

Phosphorus is an essential macronutrient for plant growth and development. However, phosphorus availability is low in many soils, and the plant's ability to acquire phosphorus from the rhizosphere is critical in the acid soils of the Brazilian Cerrado. In addition, high levels of fixed phosphate (Pi) in many soils reduce phosphorus availability to plants. Thus, Pi deficiency is a significant concern for crop growth and high yields in tropical soils. The intra- and interspecific variations in plant growth under Pi-limiting conditions are complex traits controlled by many induced or suppressed genes, comprising an intricate epistatic regulatory network interacting within cells and the external environment. The microRNA genes (miRNAs), a class of regulators that induce, degrade or repress mRNA transcription and translation, are another critical aspect of this network. As a result, changes in morphology (growth and root architecture) and physiological (enzymes, organic acids, and anthocyanin) can be observed in plants under Pi stress. Furthermore, symbiotic associations with phosphate-solubilizing bacteria and mycorrhizal fungi increase phosphorus availability to plants. Therefore, understanding mechanisms involved in plant adaptation to phosphorus deficiency is critical for developing cultivars adapted to low phosphorus levels in the Brazilian acid soils. This review addresses P acquisition and use by plants and discusses its implications in genetic breeding programs.