Fig. 1. gram mutations affect leaf growth and adabaxial asymmetry. (A) Comparisons of the length and width of fully expanded leaves of wild-type (filled bars) and gram-1 (open bars) at nodes 1 to 6. Values represent means of eight replicates and error bars, one standard deviation. (B) The adaxial wild-type leaf (top left) appears darker than the abaxial (top right). In gram mutant leaves, strips of darker tissue extend abaxially (arrowheads). (C) The wild-type adaxial leaf surface (left) consists of large, irregular pavement cells and rectangular cells towards the leaf edge (left in this image). Abaxial pavement cells (centre) are smaller and interspersed with frequent stomata (s). The edge of the leaf (right) consists of elongated edge cells (e). (D) In gram mutants, adaxial pavement cells are unaltered whereas cells at the margins are more irregular (left), edge cells are found abaxially (centre) and larger abaxial cells are seen, and stomata and hairs (h) are found at the leaf edge. (E) A transverse section of a wild-type leaf shows that, the junction between adaxial palisade mesophyll (pm) and abaxial spongy mesophyll (sm) cells runs to the edge of the leaf (arrowhead). In the gram mutant leaf (F), palisade mesophyll cells (pm) are found abaxially at the margins and adaxial cells away from the margin resemble spongy mesophyll. (G,H) gram mutants occasionally produce needle-like leaves (arrowhead in G), that appear radial in transverse section (H). (I) The arrangement of xylem elements internal to phloem in central vascular bundles of these leaves suggests a loss of adaxial leaf identity.