Soluble Sugars, Respiration, and Energy Charge during Aging of Excised Maize Root Tips.
Soluble Sugars, Respiration, and Energy Charge during Aging of Excised Maize Root Tips.
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DOI：
10.1104/pp.66.3.516
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发表时间：
1980-09
期刊：
影响因子：
7.4
通讯作者：
P. Saglio;A. Pradet
中科院分区：
文献类型：
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作者：
P. Saglio;A. Pradet
玉米根尖在25℃下老化8小时和24小时后，氧吸收下降到初始值的50%~30%，总糖(葡萄糖、果糖和蔗糖)含量也急剧下降。切除时淀粉含量很低，5小时后几乎可以忽略不计。在同一时期，呼吸商从1下降到0.75，然后保持稳定，外源糖的加入导致呼吸率迅速上升，并稳定在与外源糖浓度相关的水平。添加0.2摩尔葡萄糖是使呼吸频率恢复到初始和最大水平所必需的。这些结果表明，根尖的代谢活动高度依赖于糖的输入，切除时的碳水化合物储备不能补偿停止的输入。底物供应对呼吸的控制与二硝基酚未能刺激老化的糖枯竭根尖的吸氧作用是一致的。无论有没有葡萄糖，尽管老化的糖枯竭组织的呼吸活动大幅下降，能量电荷保持在约0.9。
Oxygen uptake and energy charge were monitored during aging of excised maize root tips and related to the soluble sugar content and exogenous sugar supply.Oxygen uptake declined immediately after excision to 50 to 30% of its initial value after 8 and 24 hours of aging at 25 C. There was also a sharp decline of the total sugar content (glucose, fructose, and sucrose). Starch content was very low at the time of excision and almost negligible 5 hours later. During the same period, the respiratory quotient declined from 1 to 0.75 and then remained stable.The addition of exogenous sugars induced a rapid rise of the respiratory rate which stabilized at a level correlated to the external sugar concentration. Addition of 0.2 molar glucose was necessary to restore the respiratory rate to the initial, also the maximum, level. These results indicate that metabolic activity of root tips is highly reliant on sugar import and carbohydrate reserves at the time of excision cannot compensate for the cessation of import. The control of respiration by substrate supply is in good agreement with the failure for dinitrophenol to stimulate oxygen uptake in aged sugar-depleted root tips.The energy charge remained constant at about 0.9, irrespective of the presence or absence of glucose and in spite of a large decline of respiratory activity in aged, sugar-depleted tissues.