The polycotyledon (pct1-2) mutant of tomato shows enhanced accumulation of PIN1 auxin transport facilitator protein

The bilateral symmetry of a dicotyledon embryo is tightly associated with the directional flow of auxin. Disruption of polar auxin flow results in various developmental abnormalities. The pct1-2 mutant of tomato, showing polycotyledony, also has enhanced polar auxin transport in hypocotyls. Immunocytochemical analysis revealed increased PIN1 protein in pct1-2 roots and hypocotyls. The mutant also displayed an increase in PIN1 transcript levels in these organs. Our results indicate that over-accumulation of PIN1 protein is likely related to increased polar transport of auxin in the pct1-2 mutant.