TRANSCRIPTS FOR A LECTIN-LIKE GENE ACCUMULATE IN THE EPIDERMIS BUT NOT THE PROTODERMIS OF THE PEA SHOOT APEX

We describe a novel pattern of tissue- and position-dependent accumula tion for transcripts encoding a lectin-like protein (Blec) in pea (Pis um sativum L.). This pattern indicates a regulatory difference between the protodermis of the apical meristem and the derived epidermal cell s of surrounding shoot apex: BlecRNA is absent or present at very low levels in protodermal cells of the apical meristem but is highly expre ssed in the derived epidermal cells of leaf primordia flanking the api cal meristem. A similar pattern is seen during floral development: tra nscripts are undetectable in the protodermis of the floral dome and fl oral organ primordia, but are first detected during organ formation an d expansion. This finding supports the hypothesis that the apical meri stem functions as a unit distinct from the surrounding shoot apex (I.U . Sussex, 1989, Cell 56, 225 229).