الفهرس 
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Abstract
The present investigation was carried out in order to have a better understanding of the various responses of wheat plant proteins to low temperatures. So two Egyptian varieties (Giza 160, Sakha 8) of wheat seedlings (3days and 6 days old) were subjected to low nonfreezing temperatures (6oC and 9oC). Plant heights and pigments content were used as a primary parameter for cold stress effect. Soluble carbohydrates, crude protein and total amino acids were studied. SDS-PAGE revealed different changes in the electrophoretic patterns of water soluble protein fraction and non-water soluble protein fraction due to cold stress. Also the results showed that cold stress induced changes in the soluble protein pattern separated by DISC-PAGE. Seven isozyme systems (peroxidase, esterase, polyphenol oxidase, glutamate oxaloacetate transaminase, alcohol dehydrogenase, malate dehydrogenase and amylase) were used to identify and characterize the effect of cold stress. The behavior of peroxidase activity and amylase enzymes activity (total, α and β) were also studied. The data show that the low temperature stress has a less effect on amylases activity of wheat seedlings comparing with control than the activity of peroxidase enzymes. The changes in the activity in most studied seedlings were less than 10% of control.
Key words: Wheat, cold stress, proteins, enzyme activity, isozymes, peroxidase, esterase, polyphenol oxidase, glutamate oxaloacetate transaminase, alcohol dehydrogenase, malate dehydrogenase, amylase.