Changes in Protein Profiles of Poplar Tissues during the Induction of Bud Dormancy by Short-Day Photoperiods

Abstract

Vegetative bud dormancy in woody perennial plants of the temperate regions is an important adaptive strategy for withstanding low winter temperatures. We used shortday (SD) photoperiods to induce bud dormancy in poplar (Populus deltoides Bartr. ex Marsh.), and characterized changes in protein profiles during dormancy development. Short days alone, under warm temperatures (25°C) induced a high level of dormancy comparable to that developed naturally. Under SD conditions the amounts of acetone/trichloroacetic acid (TCA)-insoluble dry powder (DP) increased in terminal and lateral buds, leaves and bark tissues. The total protein content in DP from buds and leaves steadily decreased while total protein from bark increased. The 2-dimensional (2-D) PAGE analyses showed that terminal and lateral buds responded similarly to SD. Four polypeptides that newly appeared or increased in abundance and five that disappeared or diminished in terminal buds during 10 weeks of treatment were also detected in lateral buds. Two of these newly apparent polypeptides were also found in bark. Similar polypeptides were not found in leaves. Changes in protein metabolism and possibly altered gene expression might be important part in the overall response of poplar to SD during dormancy development.