HYPOXIC AND ANOXIC INDUCTION OF ALCOHOL-DEHYDROGENASE IN ROOTS AND SHOOTS OF SEEDLINGS OF ZEA-MAYS - ADH TRANSCRIPTS AND ENZYME-ACTIVITY
HYPOXIC AND ANOXIC INDUCTION OF ALCOHOL-DEHYDROGENASE IN ROOTS AND SHOOTS OF SEEDLINGS OF ZEA-MAYS - ADH TRANSCRIPTS AND ENZYME-ACTIVITY
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DOI：
10.1104/pp.101.2.407
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发表时间：
1993-02-01
期刊：
影响因子：
7.4
通讯作者：
DREW, MC
中科院分区：
文献类型：
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作者：
ANDREWS, DL;COBB, BG;DREW, MC
乙醇脱氢酶（ADH）是已知优先在低O2条件下合成的糖酵解和发酵的许多酶之一。我们检测了Adh 1转录水平和ADH活性在5毫米根尖，根轴（种子根的其余部分），和玉米（玉米L。cv TX 5855）幼苗。幼苗根平均约60毫米长，从完全有氧条件下（溶液喷射40% [v/v] O2）厌氧（O2-无）条件下，或中间O2浓度。没有预先适应低O2。在根尖，缺氧诱导Adh 1转录和酶活性在6小时，但随后迅速下降，使在12至18小时都没有检测到，根尖死亡。相反，较高水平的Adh 1转录本和酶活性保持至少48小时，在根轴和芽。当诱导在6小时，在广泛的O2浓度范围内测量，在ADH活性的峰值发生在所有组织中，在4%（V/V）O2。然而，转录物的最大XiMUM水平在0至4%O2的范围内，这取决于组织。根尖缺氧诱导（在4%O2）的时间过程中表现出在6小时的转录水平的峰值，而ADH活性继续上升，在整个24小时的实验。这些结果表明，在根尖，ADH的诱导缺氧是小的和短暂的诱导相对于缺氧。
Alcohol dehydrogenase (ADH) is one of a number of enzymes of glycolysis and fermentation known to be synthesized preferentially under low O2 conditions. We examined levels of Adh1 transcripts and of ADH activity in 5-mm root tips, root axes (the remainder of the seminal root), and shoots of maize (Zea mays L. cv TX 5855) seedlings. Seedlings with roots averaging about 60-mm long were transferred from fully aerobic conditions (solutions sparged with 40% [v/v] O2) to anaerobic (O2-free) conditions, or to an intermediate O2 concentration. There was no prior acclimation to low O2. In root tips, anoxia induced Adh1 transcripts and enzyme activity at 6 h, but this was followed by a rapid decline so that at 12 to 18 h neither were detectable and the root tips were dead. In contrast, higher levels of Adh1 transcripts and enzyme activity were maintained for at least 48 h in root axes and shoots. When induction at 6 h was measured over a wide range of O2 concentrations, a peak in ADH activity occurred in all tissues at 4% (V/V) O2. MaXiMUM levels of transcripts, however, were in the range of 0 to 4% O2, depending on the tissue. The time course of hypoxic induction (at 4% O2) in root tips showed a peak in transcript levels at 6 h, whereas ADH activity continued to rise throughout the 24-h experiment. These results show that in root tips, ADH induction by anoxia was small and transient relative to induction by hypoxia.