Regulation of Plant Surface Metabolism

Asaph Aharoni
Department of Plant Sciences
Weizmann Institute of Science
P.O.B. 26
Rehovot 76100, Israel
E-mail: asaph.aharoni@weizmann.ac.il
Phone: (+972-8) 9343643;Fax: (+972-8) 9344181
Lab website: http://www.weizmann.ac.il/plants/aharoni/index.html

One of the most fundamental changes in the adaptation of plants to terrestrial environment was the formation of their surface, the cuticle. The cuticular layer plays multiple roles in plants including the regulation of epidermal permeability and non-stomatal water loss and protection against insects, pathogens, UV light, and frost. It also functions in the prevention of post-genital organ fusion, pollen-pistil interactions and cell-to-cell communication. Generation of cuticular components in epidermal cells involves four major independent biosynthetic pathways, namely those for the synthesis of cutin monomers, aliphatic wax components, triterpenoids, and aromatic metabolites (e.g. flavonoids). Our lab is interested in the regulation of the different pathways constructing the cuticle and how the secretion of their end products to the cuticle is executed. Recently, we identified an Arabidopsis transporter gene that is potentially involved in the transport of cuticle components, (e.g. wax), from the epidermal layer to the cuticle. Its down regulation by RNAi results in a dramatic effect on plant morphology, most strikingly, fusions of leaves and floral organs to leaves. We are also conducting in-depth characterization of the recently identified SHINE/WIN clade of AP2/EREBP transcription factors from Arabidopsis. Overexpression of either one of the three factors resulted in the same phenotype, primarily, a six fold increase in total cuticular wax. Strong developmental defects were also observed including increased leaf glossiness, growth retardation, leaf curling, and effects on epidermal cell differentiation. In parallel to the study of cuticular metabolism in vegetative tissues we are also investigating the cuticle in reproductive organs such as tomato fruit skin. Metabolic and expression profiling of the skin is underway to identify key enzymes, transporters and transcriptional factors mediating cuticle metabolism in this tissue.