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低渗膨胀对菠菜完整叶绿体光合作用的影响

叶济宇, 李德耀, 沈允钢

中科院上海植物生理研究所. 上海 200032

摘要

菠菜离体完整叶绿体需合适介质渗透压以保持较高的光合作用速率。当渗透压因降低介质中山梨醇浓度而降低时, 叶绿体完整率保持不变。低于临界压(约0.5MPa), 叶绿体被膜发生破裂, 并丧失CO_(2)同化能力。渗透压在0.9MPa与0.5MPa之间, 叶绿体依赖PGA的放氧抑 制, 可由加入山梨醇至正常浓度(0.33mol/L)而解除。膨涨叶绿体的ATP合成水平与正常相同, 而NADPH形成速率明显降低; NO~(-)_(2)的还原不受影响, 而PGA及OAA的还原 明显被抑制。图6参12

关键词： 完整叶绿体; 低渗膨胀; 依赖CO_(2)放氧

Effect of hypotonic swelling on photosynthesis in spinach intact chloroplasts

Ye Jiyu, Li Deyao, Shen Yungang

Shanghai Institute of Plant Physiology, Chinese Academy of Sciences. Shanghai 200032

Abstract

When the osmotic pressure of the medium was decreased by lowering sorbitol concentration from 0.33 mol/L to 0.17 mol/L, the percentage of intact chloroplasts remained unchanged until a critical osmotic pressure of about 0.5 MPa was reached. Below 0.4MPa the chloroplast envolope rupture occurred and CO_(2)fixation capacity lost. In slightly hypotonic conditions, the CO_(2)-dependent O_(2) evolution was inhibited, though the chloroplasts were still intact(Fig.1). Between 0.9 MPa and 0.5MPa, the inhibition of PGA reduction in hypotonically swollen chloroplasts could be overcome by adding sorbitol to normal concentration (0.33 mol/L)(Fig.3). Light-dependent changes of ATP and NADPH levels in intact chloroplasts were measured. By using different penetrable electron acceptors NO~(-)_(2), PGA and OAA, it was found that swelling of chloroplasts had no effect on nitrite reduction which used reduced ferredoxin as electron donor. On the other hand, PGA or OAA reduction which required NADPH as electron donor was significantly inhibited by hypotonic swelling(Fig.5).

Key words: Hypotonic swelling;Intact chloroplast;CO_(2)-dependent O_(2) evolution

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引用本文：

叶济宇, 李德耀, 沈允钢. 低渗膨胀对菠菜完整叶绿体光合作用的影响[J]. 生理学报 1995; 47 (1): .

Ye Jiyu, Li Deyao, Shen Yungang. Effect of hypotonic swelling on photosynthesis in spinach intact chloroplasts. Acta Physiol Sin 1995; 47 (1): (in Chinese with English abstract).