Changes in protein interactions of cell cycle-related genes during the dormancy-to-growth transition in pea axillary buds.

Apical dominance is a phenomenon in which a terminal bud grows predominantly and the growth of the axillary buds is suppressed. Here, we investigated the molecular mechanisms associated with cell cycle control that occur in pea axillary buds as a result of decapitation. Proliferating cell nuclear antigen (PCNA) protein was detected in both dormant and growing buds, while PCNA mRNA was absent in dormant buds. Pissa; CycB1;2 and Cdc2 proteins were undetectable during dormancy. To analyze an interaction between PCNA and Pissa;CycD3;1, we performed anti-PCNA immunoaffinity column chromatography. Pissa;CycD3;1 protein was detected in the eluate prepared from the dormant buds, but not in the eluate prepared from the growing buds. Furthermore, we performed anti-Pissa;CycD3;1 immunoaffinity column chromatography. PCNA protein was detected in the eluate prepared from the dormant buds, but not in the eluate prepared from the growing buds. These results indicated that PCNA associated with Pissa;CycD3;1 only during dormancy. In addition, the interaction between PCNA and Pissa;CycD3;1 was confirmed by a yeast two-hybrid system.