Publication Date: 2012 Mar 27 PMID: 22452856
Authors: Voo, S. S. - Grimes, H. D. - Lange, B. M.
Journal: Plant Physiol
Epithelial cells (ECs) lining the secretory cavities of Citrus peel have been hypothesized to be responsible for the synthesis of essential oil, but direct evidence for such a role is currently sparse. We used laser-capture microdissection and pressure catapulting to isolate ECs and parenchyma cells (PCs; as controls not synthesizing oil), from the peel of young grapefruit (Citrus x paradisi cv. Duncan), isolated RNA and evaluated transcript patterns based on oligonucleotide microarrays. A gene ontology analysis of these data sets indicted an enrichment of genes involved in the biosynthesis of volatile terpenoids and non-volatile phenylpropanoids in ECs (when compared to PCs), thus indicating a significant metabolic specialization in this cell type. The gene expression patterns in ECs were consistent with the accumulation of the major essential oil constituents (monoterpenes, prenylated coumarins, and polymethoxylated flavonoids). Morphometric analyses demonstrated that secretory cavities are formed early during fruit development, whereas the expansion of cavities, and thus oil accumulation, correlates with later stages of fruit expansion. Our studies have laid the methodological and experimental groundwork for in-depth studies of the processes controlling essential oil biosynthesis in Citrus peel.
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(Via Plant Physiology.)