Characterization of Arabidopsis ABCG11/WBC11, an ATP binding cassette (ABC) transporter that is required for cuticular lipid secretion†

Abstract

Summary: ABCG11/WBC11, an ATP binding cassette (ABC) transporter from Arabidopsis thaliana, is a key component of the export pathway for cuticular lipids. Arabidopsis wbc11 T‐DNA insertional knock‐out mutants exhibited lipidic inclusions inside epidermal cells similar to the previously characterized wax transporter mutant cer5, with a similar strong reduction in the alkanes of surface waxes. Moreover, the wbc11 knock‐out mutants also showed defects not present in cer5, including post‐genital organ fusions, stunted growth and a reduction in cutin load on the plant surface. A mutant line previously isolated in a forward genetics screen, called permeable leaves 1 (pel1), was identified as an allele of ABCG11/WBC11. The double knock‐out wbc11 cer5 exhibited the same morphological and biochemical phenotypes as the wbc11 knock‐out. A YFP‐WBC11 fusion protein rescued a T‐DNA knock‐out mutant and was localized to the plasma membrane. These results show that WBC11 functions in secretion of surface waxes, possibly by interacting with CER5. However, unlike ABCG12/CER5, ABCG11/WBC11 is important to the normal process of cutin formation.