Thursday, November 26, 2015
The endodermis as a checkpoint for nutrients
University of Lausanne, Department of Plant Molecular Biology, Lausanne, Switzerland
In higher plants, roots acquire water and nutrients from the soil and transport them upwards to the aerial parts. This function is reflected by their histology: water and nutrients move radially through the concentric layers of epidermis, cortex, and endodermis before entering the central cylinder where they are loaded into the xylem for transport to the aerial parts. The endodermis is a single, epithelium-like cell layer, which surr ounds the inner, conductive tissues of roots and forms a barrier that is considered crucial for the controlled uptake of nutrients into the vasculature. The barrier properties of the endodermis are mediated by Casparian Strips (CS) highly localized lignin-based modification of the primary cell wall, surrounding each endodermal cell and by a deposition of suberin lamellae in the secondary cell wall.
In the past decades, the endodermis has been largely studied at the histological and physiological level in various plant species. Our recent work in Arabidopsis identified specific mutants, markers and protocols that now provide an unprecedented opportunity to test the roles of the endodermis in nutrient uptake. Our current research indicates that the generally accepted views of endodermal function have been overly simplistic. We could show that compromising the CS integrity does not lead to a massive allocation of nutrients to the aerial parts. Currently, we are investigating in much greater details the signific ance of the suberin lamellae, its development, function and plasticity. We found that suberin development integrates nutritional and hormonal cues and in turn modulates trans – cellular transport in the endodermis. This will deepen our understanding of the e ndodermis as a selective barrier for nutrients.
Contact : Gabriel Krouk