Fig. 3. GRAM promotes marginal leaf growth. (A) The leaves of periclinal chimeras in which L2-derived cells carry an oli mutation that reduces chlorophyll content. L2-derived cells contribute a variable proportion of the internal cells of the leaf - seen as a yellow marginal region in the surface view (above) or as cells showing no red chlorophyll auto-fluorescence under UV light in section (below). (B) The loss of L2-derived tissues at the leaf margins of gram mutants is partially compensated for by an increased growth of the L3 layer. (C,D) Transverse sections of wild-type (C) and gram (D) vegetative apices probed with the CYCLIND3a probe. Note the shift in CYCLIN expression to more internal regions of gram mutant leaves.