Changes in Isoperoxidases during Cold Treatment of Dormant Pear Embryo.

The number of isoperoxidases and the intensity of certain isozymes increased with increasing periods of stratification of pear (Pyrus communis cv. Bartlett) embryos. The presence of GA(3) or kinetin during stratification enhanced the activity of certain isoperoxidases, and these enhancements were blocked in the presence of ABA which by itself had an inhibitory effect. Enhancement in isoperoxidases of pear embryos during stratification was inhibited by 6-methylpurine and cycloheximide; and in the presence of either of these two inhibitors, stratification failed to release the dormancy. Pear embryos germinated for 3 days showed changes in the pattern of isoperoxidases depending on the length of stratification.