Regulation of root hair development by the plant hormone auxin through the receptor-like kinase ERULUS and modulation of cell wall enzyme activity.

The main function of plant roots is to forage for soil resources. Root hairs, tubular extensions of the root's outer cell layer, represent 70% of the root surface area and are the primary site of water and nutrient uptake. When grown in specific soil conditions, mutants with shorter root hairs have reduced plant fitness. Understanding how factors like the plant hormone auxin control root hair development are therefore critical to optimise agricultural systems with respect to water and fertilizer use. The data are disjointed and an integrated view is lacking. We will use the model plant Arabidopsis and our recently published mutant that grows shorter root hairs. The expression of the mutated gene, ERULUS, is directly controlled by auxin and normally encodes a kinase, a protein that regulates its targets' activity by phosphorylation. Changes in specific cell wall enzyme activity, modifying pectins, causes strongly reduced root hair growth in the mutant. Our aim is to elucidate the pathway that starts from auxin, involves ERULUS and cell wall metabolism and results in normal root hairs. We identified 3 objectives that concentrate on different levels: i) Unravelling the control of ERU expression by auxin ii) Characterization of ERU protein functionality iii) Elucidation of ERU-mediated control of root hair growth through specific cell wall enzymes The data gathered during these 3 work packages will allow me to interconnect pathways up- and downstream of the identified ERULUS kinase and it will probe auxin regulation throughout the root hair expansion network.

Keywords:KINASE, AUXINS, GROWTH REGULATORS IN PLANTS, HORMONES

Disciplines:Biochemistry and metabolism, General biology, Plant biology, Systems biology, Medical biochemistry and metabolism