Author:
Marzol Eliana,Borassi Cecilia,Ranocha Philippe,Aptekman Ariel. A.,Bringas Mauro,Pennington Janice,Paez-Valencia Julio,Pacheco Javier Martínez,Rodríguez Garcia Diana Rosa,del Carmen Rondón Guerrero Yossmayer,Carignani Mariana,Mangano Silvina,Fleming Margaret,Mishler-Elmore John W.,Blanco-Herrera Francisca,Bedinger Patricia,Dunand Christophe,Capece Luciana,Nadra Alejandro D.,Held Michael,Otegui Marisa S.,Estevez José M.
Abstract
AbstractRoot hair cells are important sensors of soil conditions. Expanding several hundred times their original size, root hairs grow towards and absorb water-soluble nutrients. This rapid growth is oscillatory and is mediated by continuous remodelling of the cell wall. Root hair cell walls contain polysaccharides and hydroxyproline-rich glycoproteins including extensins (EXTs).Class-III peroxidases (PRXs) are secreted into the apoplastic space and are thought to trigger either cell wall loosening, mediated by oxygen radical species, or polymerization of cell wall components, including the Tyr-mediated assembly of EXT networks (EXT-PRXs). The precise role of these EXT-PRXs is unknown.Using genetic, biochemical, and modeling approaches, we identified and characterized three root hair-specific putative EXT-PRXs, PRX01, PRX44, and PRX73. The triple mutantprx01,44,73and the PRX44 and PRX73 overexpressors had opposite phenotypes with respect to root hair growth, peroxidase activity and ROS production with a clear impact on cell wall thickness.Modeling and docking calculations suggested that these three putative EXT-PRXs may interact with non-O-glycosylated sections of EXT peptides that reduce the Tyr-to-Tyr intra-chain distances in EXT aggregates and thereby may enhance Tyr crosslinking. These results suggest that these three putative EXT-PRXs control cell wall properties during the polar expansion of root hair cells.
Publisher
Cold Spring Harbor Laboratory