Protein changes in the flower buds of Japanese pear during breaking of dormancy by chilling or high-temperature treatment

Abstract

The dormancy of Japanese pear (Pyrus pyrifolia Nakai) floral buds was broken by prolonged chilling or short-term high-temperature treatment (45 °C for 4 hours). Changes in the protein profiles of the floral buds were studied using two-dimensional electrophoretic analysis (2-DE). The quantities of nine cold-induced proteins (CIPs) increased in the floral buds with increases in chill unit (CU) value, but did not change rapidly when bud dormancy was near completion. When dormancy of floral buds was broken by high-temperature treatment, nine heat-shock proteins (HSPs) accumulated. These HSPs were distinct from the CIPs. The isoelectric point of the 19-kDa CIP shifted to the basic side by high-temperature treatment as well as by chilling. These results suggest that the 19-kDa protein may be a usable marker to measure the degree of bud dormancy in Japanese pear.