The role of ethylene in root hair growth in Arabidopsis

Ethylene promotes root hair development in many higher plants. Recently the role of ethylene has been investigated in Arabidopsis because of the range of genetic resources available in this species. Root hairs in the Arabidop sis root form on specialized epidermal cells (trichoblasts) located in the cleft between underlying cortical cells. Hairless epidermal cells develop f rom atrichoblasts that are located over single cortical cells. Ethylene not only promotes root hair outgrowth but also causes cells that are normally hairless to form root hairs. This suggests that ethylene may play a dual fu nction in the formation of root hairs. Firstly it may play a role in hair i nitiation and secondly may be required for the elongation of hairs. Alterna tively it may suggest that these are two parts of the same process.