Citrus x paradisi Transcriptome or Gene expression. Citrus x paradisi

Epithelial cells (EC) lining the most inner layers of secretory glands in Citrus peel are hypothesized to be the specialized cells that synthesize citrus essential oil. The major biosynthetic pathway(s) for essential oil are therefore postulated to be specifically and highly active in EC; transcripts that are involved in the pathway(s) are expected to be highly up-regulated in the cells as well. We performed cell-specific transcriptional analysis using GeneChip Citrus Genome Arrays to probe the global gene expression in EC during initial stage of essential oil biosynthesis and to identify groups of highly expressed genes in the EC. Overall design: Grapefruits of two different sizes (diameters at 28 mm and 41 mm), at which points where biosynthesis of essential oil entering its active phase, were selected for the purpose of this experiment. For comparison, we selected parenchyma cells (PC), the non-oil-biosynthesizing cells, as the control cell type. Grapefruit peels were fixed, embedded in paraffin, sectioned and mounted on slides prior to cells isolation using laser microdissection and pressure catapulting. RNA was extracted from the isolated cells and then used for microarray hybridization. Transcriptional analysis were carried out by comparing transcript profiles between different cell types of the same time points, and same cell type at the different time points.