Poster: Vegetative Development

Abs # 429: ADL genes are required for adaxial-abaxial pattern formation in rice leaves

Presenter:	Obara, Mari K., aa17006@mail.ecc.u-tokyo.ac.jp
Authors	Obara, Mari K. (A)   Hayashida, Emi  (A)   Nagato, Yasuo  (A)
Affiliations:	(A): Department of Agricultural and Environmental Biology, University of Tokyo

Rice leaves are polarized along proximal-distal (sheath-blade), central- marginal and adaxial-abaxial axes. In this study, we analyzed two interesting mutants involved in the adaxial-abaxial pattern formation. We have identified two non-allelic recessive mutants of rice in which adaxial characteristics of leaf blade were also detected in the abaxial side. They were designated adaxialized leaf1 (adl1) and adl2. Both adl1 and adl2 leaves were rolled downward (abaxial side became inside) and frequently twisted. In wild-type rice, adaxial epidermis of leaf blade is characterized by the presence of bulliform cells. In adl1 and adl2, bulliform cells were differentiated in the abaxial epidermis, as well as in the adaxial side. Thus, the epidermis of these mutants were adaxialized. Since the adaxial-abaxial polarization of mesophyll tissue is not apparent anatomically, we need a new marker which shows different expression pattern between adaxial and abaxial sides. We identified an available mutant adaxial snowy leaf (ads), in which many of adaxial mesophyll cells were albinos, while all abaxial mesophyll cells were normal green. In adl2 ads double mutant, albino cells distributed in both adaxial and abaxial sides of mesophyll tissue, indicating that adl2 mesophyll cells were also adaxialized. Thus, in adl1and adl2 leaves abaxial characteristics were lost, and adaxial characteristics were extended to the abaxial side. In adl1 and adl2, incipient leaf primordium emerged at an extremely apical position of the SAM compared to that of the wild type. These results suggest that the adaxial-abaxial patterning of leaves is closely associated with the position of the primordial insertion in the SAM.