CHARACTERIZATION OF A GENE TRANSCRIBED IN THE L2 AND L3 LAYERS OF THETOBACCO SHOOT APICAL MERISTEM

Recent genetic and molecular studies have been initiated to uncover th e fundamental cellular processes unique to the shoot apical meristem. Our previous work resulted in the isolation of a cDNA clone derived fr om tobacco apex RNA, A3, that appeared to be transcriptionally restric ted to the shoot apex regardless of developmental stage. Here the DNA sequence and in situ RNA analysis of A3 is presented. The A3 gene pote ntially encodes a small hydrophilic polypeptide, the sequence of which is unique to current data bases. It has been found that transcripts o f the A3 gene are confined to the subepidermal and internal cell layer s of the tobacco shoot apical meristem throughout development, become localized to undifferentiated floral organ primordia, and diminish as the developmental potential of the meristematic tissue becomes restric ted.