The Effect of Stratification and Thidiazuron Treatment on Germination and Protein Synthesis of Pyrus serotina Rehd cv. Niauli

Breakage of seed dormancy in Pyrus serotina Rhed cv. Niauliis achieved by cold treatment. The chilling time necessary forgermination of Pyrus serotina Rhed cv. Niauli seeds was determined,and synthesis of polypeptides during stratification and thidiazuron(TDZ) treatments was investigated. The chilling time requiredwas about 21 d. The longer the chilling time, the higher thegermination percentage. The effect of 200 µM TDZ on seedgermination was equivalent to 14-21 d of chilling, and TDZ couldbe used as a substitute for cold treatment. Use of in vivo ³⁵S-methionine label and two-dimensional gel electrophoretic analysisof polypeptides revealed that the patterns of untreated (dormant)and chilled embryonic axes differed significantly in their polypeptideprofiles. The difference became conspicuous after prolongedchilling exposure. During 28 d of stratification followed by5 d of incubation at 25 °C, changes were noted in 35 solublepolypeptides (ESPs) and 38 pellet polypeptides (EPPs) from theembryonic axis. The changes included increase, decrease or newlyinduced synthesis. Common patterns of changes in soluble andpellet polypeptides of embryonic axes, can be broken down intofour categories. The possible functions and roles of these fourcategories of polypeptides in breaking seed dormancy and germinationare discussed. Although the magnitude of polypeptide changesare not as extensive in seeds receiving TDZ treatment as afterstratification, similar polypeptide changes were co-inducedby the two treatments.Copyright 1994, 1999 Academic Press Stratification, protein synthesis, pear, Pyrus serotina, Thidiazuron, TDZ