Figure 2.

Gene expression patterns revealed by GUS reporter histological staining resulting from gene or enhancer trap insertion. Most genes are expressed in a discrete subset of tissues or cell types, and expression can be assayed in a variety of organs including roots (not shown), leaves, and stems. Gene trap line cGT-1-pop1-708 (A) is an exception, and the tagged gene is expressed uniformly. Examples are shown of expression patterns that would not be readily revealed by other current gene expression technologies (e.g. microarrays). Gene trap line cGT-1-pop1-496 (B) is expressed in the hydathodes of the leaf. Lines cET-1-pop1-234 (whole mount staining of stem; [C]) and cET-1-pop1-13 (cross-section through node; [D]) are expressed in the vascular leaf traces. Line cET-1-pop1-164 (cross-section through petiole; [E]) includes expression on the adaxial side of the petiole. The different tissue and living cell types of the stem can be assayed for gene expression, including the interfascicular zone stained by cET-1-pop1-103 (F), the ground tissues in cET-1-pop1-333 (G), and the pith in cET-1-pop1-329 (H).