Location: Plant Physiology and Genetics ResearchTitle: The glossyhead1 Allele of ACC1 Reveals a Principal Role for multidomain acetyl-coenzyme a carboxylase in the biosynthesis of cuticular waxes by arabidopsis[c][w][oa] Author
Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2012
Publication Date: 11/1/2012
Citation: Lu, S., Zhao, H., Parsons, E.P., Xu, C., Kosma, D.K., Xu, X., Chao, D., Lohrey, G., Bangarusamy, D.K., Wang, G., Bressan, R.A., Jenks, M.A., 2012. The glossyhead1 Allele of ACC1 Reveals a Principal Role for multidomain acetyl-coenzyme a carboxylase in the biosynthesis of cuticular waxes by arabidopsis[c][w][oa]. Plant Physiology, Vol. 157, pp. 1079-1092. Interpretive Summary: Screens of mutagenized populations in Arabidopsis uncovered a novel mutant designated glossyhead1 (gsd1) having a severely disturbed cuticle. Besides a visibly glossy stem, the mutant exhibited postgenital fusion in the inflorescence, reduced fertility, and elevated transpiration rates. The gsd1 locus was mapped, and the causal gene identified as a novel allele of Acetyl-CoA Carboxylase1 (ACC1), a gene encoding the main enzyme in cytosolic malonyl-CoA synthesis. Broad based analysis of the lipid profile of gsd1 provided evidence that the ACC1 protein has its primary function in the synthesis of cuticular waxes, rather than other lipid classes such as suberin, cutin, or seed oils. Transcriptome analysis showed that the gsd1 mutation caused a change in expression of many genes, but unexpectedly, most genes affected were associated with plant stress response pathways rather than lipid metabolic pathways. These findings reveal that ACC1 function is tied directly to the regulation of plant stress response, likely through effects on lipid signaling.
Technical Abstract: A novel mutant of Arabidopsis thaliana having highly glossy inflorescence stems, post-genital fusion in floral organs, and reduced fertility, was isolated from an EMS-mutagenized population and designated glossyhead1 (gsd1). The gsd1 locus was mapped to chromosome 1, and the causal gene identified as a new allele of Acetyl-CoA Carboxylase1 (ACC1), a gene encoding the main enzyme in cytosolic malonyl-CoA synthesis. This is the first mutant allele of ACC1 that does not cause lethality at the seed or early germination stages, allowing for the first time a detailed analysis of ACC1 function in mature tissues. Broad lipid profiling of mature gsd1 organs revealed a primary role for ACC1 in the biosynthesis of the very long chain fatty acids (VLCFAs; C20:0 or longer) associated with cuticular waxes and triacylglycerols. Unexpectedly, transcriptome analysis revealed that gsd1 has limited impact on any lipid metabolic networks, but instead has a large effect on environmental stress responsive pathways, especially senescence and ethylene synthesis determinants, indicating a possible role for the cytosolic malonyl-CoA derived lipids in stress response signaling.