Roots rely on apoplastic barriers for nutrient absorption. However, little is known about the establishment of these barriers within the lateral roots. The branching, permeability of the outer cell layers and differentiation of the endo- and exodermis are studied in primary roots and various laterals of Zea mays under different stress factors of agronomic importance (salinity, heavy metal toxicity, hypoxia, etc.).
Tylová et al. propose that fine laterals represent portions of a complex root system with a less advanced state of endodermis and exodermis differentiation, but with substantial ability to modify maturation of exodermis in response to environmental conditions. Branching and establishment of barriers in fine laterals may be at the crux of the root system – rhizosphere interaction.