Evaluation of the importance of lactate for the activation of ethanolic fermentation in lettuce roots in anoxia
Evaluation of the importance of lactate for the activation of ethanolic fermentation in lettuce roots in anoxia
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DOI：
10.1034/j.1399-3054.2000.100105.x
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发表时间：
2000-05-01
影响因子：
6.4
通讯作者：
Kato-Noguchi, H
中科院分区：
文献类型：
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作者：
Kato-Noguchi, H
根据Davies-Roberts假说，植物主要通过乳酸生产的爆发来响应氧气限制，并且细胞质中的pH值下降激活乙醇发酵。为了在莴苣（莴苣L.）中评价该系统，使幼苗经受缺氧和乙醇脱氢酶（ADH，ECwww.example.com）、丙酮酸脱羧酶（PDC，4.1.1.1）和乳酸脱氢酶（LDH，1.1.1.27）的体外活性，并且仅在幼苗的根中测定乙醇、乙醛和乳酸的浓度：根中ADH和PDC的体外活性在缺氧中增加，而LDH活性没有测量到显著增加。1.1.1.1在6 h时，缺氧条件下根系中ADH和PDC活性分别是空气条件下的2.8倍和2.9倍。乙醇和乙醛在缺氧条件下迅速积累，6 h时分别比空气中增加8倍和4倍。因此，乙醇和乙醛的产生并没有增加乳酸的合成。在氧气存在下，用抗霉素A和水杨基异羟肟酸（它们是呼吸抑制剂）处理莴苣幼苗，增加了乙醇和乙醛的浓度，但没有增加乳酸的浓度。这些结果表明，乙醇发酵可以被激活，而无需预先激活乳酸发酵，并且可能不受氧浓度的直接调节。
According to the Davies-Roberts hypothesis, plants primarily respond to oxygen limitation by a burst of lactate production and the resulting pH drop in the cytoplasm activates ethanolic fermentation. To evaluate this system in lettuce (Lactuca satixa L.), seedlings were subjected to anoxia and in vitro activities of alcohol dehydrogenase (ADH, EC 1.1.1.1), pyruvate decarboxylase (PDC, EC 4.1.1.1) and lactate dehydrogenase (LDH, EC 1.1.1.27) and concentrations of ethanol, acetaldehyde and lactate mere determined in roots of the seedlings:The in vitro activities of ADH and PDC in the roots increase in anoxia,,whereas no significant increase was measured in LDH activity. At 6 h, the ADH and PDC activities in the roots kept in anoxia were 2.8- and 2.9-fold greater than those in air, respectively. Ethanol and acetaldehyde in the roots accumulated rapidly in anoxia and increased 8- and 4-fold compared with those in air by 6 h, respectively. However, lactate concentration did not increase and an initial burst of lactate production was not found. Thus, ethanol and acetaldehyde production occurred without an increase in lactate synthesis, Treatments with antimycin A and salicylhydroxamic acid, which are respiratory inhibitors, to the lettuce seedlings in the presence of oxygen increased the concentrations of ethanol and acetaldehyde but not of lactate, These results suggest that ethanolic fermentation may be activated without preceding activation of lactate fermentation and may be not regulated by oxygen concentration directly.