Changes in L-isoaspartyl Methyltransferase, Storage Components and Anti-oxidant Enzymes Activities During Accelerated Ageing in Cucumber ( Cucumis sativus L.) Seeds

摘要

Cucumber seeds were assayed to determine whether the onset of tolerance to drying condition was related to changes in some biochemical and physiological properties associated with accelerated ageing. In the present study, accelerated ageing of seeds at 42±1°C and 100% relative humidity reduced the moisture content from 36.2 to 6.4%, with initial mean dry weight of 146.4 mg g^-1 decreased to 30.6 mg g^-1. The initial seed germination of 84.6% reduced to 50.6% and the percentage of electrolytes leakage significantly increased by ten times of initial activity accompanied by a correlative decrease in L-isoaspartyl methyltransferase (L-IAMT) activity. A reduction in the total content of storage components such as proteins, sugars, starch and lipids, except an increase in amino acid s, was recorded during the accelerated ageing. The decrease in the activities of anti-oxidant related enzyme, peroxidase (POX), was also noticed. Exceptionally, catalase (CAT) showed different pattern by early increase in its activity, a peak activity at 4th day and later decrease under the same condition. The present study suggested that seed deterioration and loss of viability were resulted from the decrease in L-IAMT activity and the changes in storage components as well as anti-oxidant related enzymes. Under the condition the degradation of stored reserves in Cucumis sativus was enhanced.