大豆種子萌芽生長期間貯藏養分的消長及Isocitrate Lyase, Malate Synthetase活性的研究

Abstract

在26 C下萌芽生長的大豆種子，不論光照與否，其子葉中所含的蛋白質、脂肪及糖含量，一般是隨著萌芽日數的增加而遞減，惟在黑暗中萌芽生長的幼苗，其子葉中的糖含量在第八天則稍有上升的現象；幼苗的胚軸部份，其內各種養分的含量，則因光照與否會有很顯著的差異。由測定乙醛酸循環 (glyoxylate cycle) 中關鍵酵素活性的結果，發現不論光照與否，胚軸中僅在萌芽生長的第二日有 isocitrate lyase 及 malate synthetase 兩種酵素的活性；而在子葉中，則測知上述兩種酵素的活性隨萌芽日數的增加而上升，並於第八日達到最大。此與黑暗萌芽生長的幼苗子葉中，第八日糖含量上升的現象相配合，也說明了大豆種子在萌芽過程中，確實有乙醛酸循環的存在。 Soybean seeds were soaked in water for anhour and then germinated at 26 C. The storageproteins, lipids, and sugars in the cotyledons(dry weight basis) of the germinating seedlingscontinuously decreased after imbibition, eitherunder light or dark conditions; however, thesugar content in the dark increased on the 8thday and then declined. The changes of re-serves in the axis are varied depending on thelight factor. Slight activities of isocitrate lyaseand malate synthetase in the glyoxylate cyclein the axis were detected on the 2nd day afterimbibition, while both enzyme activities in-creased in the cotyledons from the 2nd dayonward and reached their maximum on the 8thday, both under light and dark conditions. Thisindicates that the increase of the sugar contentin the cotyledons in the dark on the 8th daywas the function of both enzymes, and furtherverifies that the glyoxylate cycle is one of themetabolic processes in soybean seedlings duringgermination and the early growth period.