Laser-Capture Microdissection, a Tool for the Global Analysis of Gene Expression in Specific Plant Cell Types: Identification of Genes Expressed Differentially in Epidermal Cells or Vascular Tissues of Maize[W]

TLDR

Laser‑capture microdissection (LCM) enables one‑step isolation of large, homogeneous cell populations, a technique proven in mammalian cDNA and proteomics studies but previously limited in plants by cell walls and ice‑crystal formation. In this study, maize coleoptile tissues were fixed, cryoprotected, and mounted on adhesive slides to capture over 10,000 epidermal and vascular cells, whose RNA was amplified with T7 polymerase and hybridized to an 8,800‑gene maize cDNA microarray. The analysis identified roughly 250 genes with preferential expression in epidermal or vascular cells, demonstrating that LCM combined with microarrays permits high‑resolution global gene‑expression profiling in plants and promises deeper insight into cell‑type–specific biology.

Abstract

Abstract Laser-capture microdissection (LCM) allows for the one-step procurement of large homogeneous populations of cells from tissue sections. In mammals, LCM has been used to conduct cDNA microarray and proteomics studies on specific cell types. However, LCM has not been applied to plant cells, most likely because plant cell walls make it difficult to separate target cells from surrounding cells and because ice crystals can form in the air spaces between cells when preparing frozen sections. By fixing tissues, using a cryoprotectant before freezing, and using an adhesive-coated slide system, it was possible to capture large numbers (>10,000) of epidermal cells and vascular tissues (vascular bundles and bundle sheath cells) from ethanol:acetic acid–fixed coleoptiles of maize. RNA extracted from these cells was amplified with T7 RNA polymerase and used to hybridize a microarray containing ∼8800 maize cDNAs. Approximately 250 of these were expressed preferentially in epidermal cells or vascular tissues. These results demonstrate that the combination of LCM and microarrays makes it feasible to conduct high-resolution global gene expression analyses of plants. This approach has the potential to enhance our understanding of diverse plant cell type–specific biological processes.