Fig. 2. Rld1-O alters adaxial/abaxial polarity in the leaf. The maize leaf (A,B) comprises sheath (s) and blade (b) tissues separated by the auricle (a) and adaxial ligule (l). Rld1-O leaves (C) have narrow blades that roll upwards, and frequently develop an abaxial ligule (arrow) and clear sectors with fewer minor veins and no photosynthetic tissue (arrowhead). The ectopic abaxial ligule (D) is narrower, shorter and arises at a slightly different position along the proximodistal axis than the normal adaxial ligule. Rld1-O causes a partial inversion in adaxial/abaxial polarity and development of ectopic outgrowths on the abaxial leaf surface (E). Bulliform cells (arrows) are displaced to the abaxial epidermis and schlerenchyma cells (asterisk) develop on the adaxial rather than the abaxial side of intermediate veins. ad, adaxial; ab, abaxial.