Abstract
Phalaenopsis frequently suffer from chilling injury under low temperature. The chilling injury may cause leaf chlorosis and growth retardation. Chilling may also result in plant death and economic loss. To gain more insights of molecular mechanisms of chilling tolerance, genes possibly associate with low temperature condition in Phalaenopsis were isolated using the cDNA subtraction method. Chilling-resistant TS97 and chilling-sensitive TS365 plants were treated with either 4℃/dark (TS97-4℃ & TS365-4℃) or 25℃/dark (TS97-25℃ & TS365-25℃), but control plants were in normal condition (TS97-L & TS365-L). After two days, total RNA was isolated from leaves and used for cDNA subtraction. Partial cDNA fragments of catalase、polyubiquitin glyceraldehyde-3-phosphate dehydrogenase and ATP/ADP translocator genes were obtained. It was reported that some antioxidant enzymes were induced at low temperature. So we focused on the expression of catalase in different conditions.The catalase mRNA levels were analyzed with Northern blots. We found that the expression of TS365 catalase mRNA was significant reduced at 4℃ in the dark. At 4℃ in the dark TS365 catalase mRNA level was also less than that of TS97. Moreover, the catalase activity in TS365 was lower than that in TS97 at 4℃ in the dark. Although catalase was not induced by low temperaure, a significant reduction was found in the expression of TS365 at 4℃. The reduction of catalase gene expression in TS365 maybe related to chilling injury.Abstract-----------------------------------------ii謝誌--------------------------------------------iii名詞縮寫-----------------------------------------iv前言----------------------------------------------1材料與方法---------------------------------------10結果---------------------------------------------20討論---------------------------------------------25參考文獻-----------------------------------------31表-----------------------------------------------40圖-----------------------------------------------45附錄---------------------------------------------56