Evidence for down-regulation of ethanolic fermentation and K+ effluxes in the coleoptile of rice seedlings during prolonged anoxia
文献类型: 外文期刊
第一作者: Colmer, TD
作者: Colmer, TD;Huang, SB;Greenway, H
作者机构:
关键词: energy maintenance requirement;ethanolic fermentation;membrane permeability;potassium;phosphate;solute net uptake or loss
期刊名称:JOURNAL OF EXPERIMENTAL BOTANY ( 影响因子:6.992; 五年影响因子:7.86 )
ISSN: 0022-0957
年卷期: 2001 年 52 卷 360 期
页码:
收录情况: SCI
摘要: Ethanolic fermentation, the predominant catabolic pathway in anoxia-tolerant rice coleoptiles, was manipulated in excised and 'aged' tissues via glucose feeding. Coleoptiles with exogenous glucose survived 60 h of anoxia, as evidenced by vigorous rates of K+ and phosphate not uptake and growth of roots and shoots when re-aerated. In contrast, coleoptiles without exogenous glucose showed net losses of K+ and phosphates starting 12 h after anoxia was imposed and these did not recover fully when re-aerated after 60 h of anoxia. Ethanol production (pmol g(-1) FW h(-1)) declined from about 7.5 during the first 12 h of anoxia to 5 or 2.2 after 48-60 h, in coleoptiles with or without exogenous glucose, respectively. Carbohydrate concentrations changed only slightly in anoxic coleoptiles with exogenous glucose due to net glucose uptake at 2.6 mu mol g(-1) FW h(-1). Ethanolic fermentation, and therefore ATP production, may have been down-regulated after an initial period of acclimation to anoxia in coleoptiles with exogenous glucose. Maintenance requirements for energy were assessed to be 3.4-7.6-fold lower in these anoxic coleoptiles than published estimates for non-growing aerated leaf tissues. A modest part of the required economy in energy consumption would have been derived from diminished ion transport; anoxia reduced K+ and phosphate net uptake by 70-90% in these coleoptiles. K+ efflux was 10-fold lower in anoxic than in aerated coleoptiles with exogenous glucose. Using the unidirectional efflux equation, the membrane permeability to K+ was estimated to be 17-fold lower in anoxic than in aerated coleoptiles, presumably due to predominantly closed K+ channels.
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