水逆境對大豆生長及細胞膜生理現象影響之研究

Abstract

本研究分?「水耕生長」和「蛭石生長」兩種缺水處理的大豆幼苗，研究其生長及細胞膜生理的變化。給與12小時的缺水處理後，水耕生長的幼苗葉片水勢由-0.6MPa下降到-1.3MPa。蛭石生長的幼苗則給予缺水1、2、3天的處理後，葉片水勢由-1.0MPa分別下降到-1.3、-1.4、-1.9MPa。缺水處理期間測得其根、莖、葉和子葉等各部位的鮮重、乾重、含水量。在缺水處理時，根的乾重比全株乾重的比?會上昇，而葉的乾重比全株乾重的比?會下降。 缺水處理之前後的根和葉分別分離其細胞膜並測定膜中ATPase在20?50℃的活性，發現水耕組葉經過缺水處理12小時後的ATPase的活性沒有明顯的變化，但是蛭石栽培組的葉經缺水處理後ATPase的活性在處理一天有些微的上昇，而後第二、三天則下降。缺水的處理後根的ATPase活性在水耕栽培組和蛭石栽培組都會造成下降。 將蛭石栽培組分離的細胞膜抽出脂質作分析，發現缺水的處理下，每單位鮮重的細胞膜脂質含量減少，並且構成細胞膜脂質的成分比例有所改變，其支鏈上的不飽和脂肪酸數量降低的現象。

8-day-old soybean seedlings were grown in hydroponics and in vermiculite system. Soybean which grow in hydroponics system was dried in air for 12 hours. Soybean which grow in vermiculite was treated with withholding water for 1, 2 and 3 days. After treatment, roots and leaves were harvested and water potential, fresh weight and dry weight were measured. Plasma membrane isolated from roots and leaves were purified by using two-phase partition method. and then assayed their ATPase activity. components of lipids and acyl side chains of lipids. The ATPase activity of vermiculite-growing soybean plants were higher than that grown in hydroponics. Water stress reduced the ATPase activity of roots both in vermiculite-growing and hydroponics-growing plants. The ATPase activity of leaf was not reduced in hydroponics-growing soybeans after water-stress treatment. The ATPase activity was reduced after withholding water 2 days in vermiculite-growing soybean seedlings. The lipid quantity of plasma membrane was reduced by water-stress. Lipid composition of plasma membrane were changed. The lipids contained less unsaturated fatty acyl chains after water-stress treatment.