Abstract
In dicotyledonous plants, the apical region of the embryo acquires bilateral symmetry in addition to previous radial symmetry as two cotyledons develop at the opposite position. Mutations in the PIN1 (PIN-FORMED1) and PID (PINOID), cause comparable defects in seedlings, as cotyledons fusion and modified cotyledon number. The pin1 pid double mutantion severely suppressed the cotyledon development. In these mutants, we analyzed expression patterns of several marker genes. The results suggest that PIN1 is involved in establishment of bilateral pattern, that PID is involved in maintaining bilateral symmetry, and that PIN1 and PID coordinately promote cotyledon development through the regulation of CUC genes expression. To understand auxin distribution, we also analyzed expression pattern of YUCCA, which encodes the enzyme involved in IAA biosynthesis. Depending on these results, we want to discuss that auxin distribution through PIN1 and PID is involved in cotyledon development and cotyledon separation with bilateral symmetry.
