Abstract

The growth, betaine aldehyde dehydrogenase, malate dehydrogenase, phosphatase and peroxidase of spinach have been measured over a range of salinities. A slight decrease in fresh weight of the shoot was found with increasing salinity above 100mM NaCl; at 300mM NaCl, the fresh weight growth of the root, or the cotyledon was drastically inhabited. Tissue enzyme activities were stydies throughout the experimental range. Betaine aldehyde dehydrogenase was restricted to the shoot of spinach, not detected in the root or the cotyledon. Betaine aldehyde dehydrogenase increased significantly at 150mM NaCl, and 3-fold increase at 300mM NaCl. However, fresh weight growth, malate dehydrogenase, alkaline phosphatase showed the similar inhibition at a salinity higher than 150mM NaCl. Peroxidase of salinized spinach was stimulated slightly. It was suggested that the increased betaine aldehyde dehydrogenase of salonized spinach may reflect the betaine biosynthetic pathway accelerated somehow by an incremental salt stress.

中文摘要

萍菜幼苗培養於水耕溶液，逐步增加溶液中食鹽的濃度。由50mM NaCl 至300mM NaCl處理期間，分別測定對照組與處理組之植株地上部皮根系之鮮重量，Betaine aldehyde DH，Malate DH，Phosphatase及Peroxidase之活性。結果顯示betaine aldehyde DH只分佈於植株地上部，且於植株接受了150mM NaCl處理後，酵素活性有明顯增加，至300mM NaCl處理後，此酵素活性增加3倍左右。然而鮮重量，Malate DH，Alkaline phosphatase活性卻於鹽分高過150mM NaCl時，已有抑制現象。此情形同時發生於植株地上部及根系。 由此結果討論菠菜植株於鹽分處理後，betaine aldehyde DH之活性增加，反映了betaine 生物合成步驟之增加，因此作為菠菜以osmoreglation來抗鹽的一種機制。