Root cortical aerenchyma inhibits radial nutrient transport

Root cortical aerenchyma (RCA) provides an adaptation to low nutrient availability by reducing the metabolic cost of soil exploration. Hu et al. use radiolabelling to investigate uptake of phosphate, sulphate and calcium in roots of maize (Zeay mays) differing in their degree of RCA formation. They find that in each of the three genotypes studied the rate of phosphate exudation of high RCA genotypes is significantly less than that of low RCA genotypes, and that radial nutrient transport of phosphate and calcium is negatively correlated with the extent of RCA for some of the genotypes. The results support the hypothesis that RCA can reduce radial transport of some nutrients in some genotypes, which could be an important trade-off against the reduced cost of root production.