Potential and limitations to improving crops for enhanced phosphorus utilization

Phosphorus (P) is an essential element required for cellular function and when deficient has a significant impact on plant growth and fecundity. Poor availability of P in soil and consequent P-deficiency represents a major constraint to crop production globally (Runge-Metzger 1995). Soil P status is also a key factor that controls the competitive dynamics and species composition in different natural ecosystems (McGill and Cole 1981; Attiwill and Adams 1993), and thus may have significant impact on biodiversity (Wassen et al. 2005). Many plant species have evolved in P-limited environments and, as a consequence, are known to possess a number of adaptive features that can enhance the acquisition of P from soil (Raghothama 1999; Vance et al. 2003; Richardson et al. 2005). However, ongoing selection of crop cultivars, in nutrient replete environments, for traits such as yield and vigor (and thus an adaptation to optimal production systems), may have resulted in cultivars that have ‘lost’ adaptive traits that are required to cope with P-deficiency (Manske et al. 2000; Buso and Bliss 1988). Identification of such traits and their introduction into elite material from traditional cultivars, wild relatives and other species through modern approaches in breeding (e.g. marker-assisted selection and/or genetic manipulation) may provide new opportunities to improve the efficiency of P-uptake by crop plants.