CELL TYPE-SPECIFIC AND POSITIONALLY SPECIFIC REGULATION OF THE ALDOLASE-P GENE-EXPRESSION IN RICE SEEDLINGS

We describe here different regulation of the AldP gene, a nuclear gene encoding chloroplast aldolase, in different tissues and growth ages o f rice seedlings. Expression of the AldP gene is mesophyll cell-specif ic, and increases from the basal to the upper region in each leaf. The gene expression is repressed in the dark-grown leaf blade, but is ind uced by a short-term-exposure to light, to a level higher than that se en in the normal leaf blade. However, the light-inducibility differs a mong the tissues, and shows different patterns among leaf positions; i .e., the extent of light-induction is higher in the third leaf blade a s compared with the earlier developed second leaf blade. Such position al differences in the regulation are also seen in the leaf sheath, The se responses are not accompanied by changes of the cell type specifici ty in the expression.