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Abstract：
Flooding results in induction of anaerobic metabolism in many higher plants. As an important component of anaerobic energy production, alcohol dehydrogenase (ADH) activity increases markedly in response to flooding in white clover, Trifolium repens. Significant inter-individual variation in flood-induced ADH activity exists in natural populations of T. repens. The genetic basis of this variation was analyzed by offspring-midparent regression of data from 75 greenhouse reared families; the estimated heritability of flood-induced ADH activity was 0.55 (±0.13). Genetic variation in flood-induced ADH activity has pronounced effects on physiological response and flood tolerance in this species. ADH activity is positively correlated with the rate of ethanol production, indicating that observed in vitro activity differences are manifested in in vivo physiological function. T. repens plants with higher ADH activities during flooding have greater flood tolerance (measured as growth rate when flooded/unflooded growth rate). Variation in ADH activity during flooding accounts for more than 79% of the variance in flood tolerance. On the basis of a limited field survey of populations occupying three sites differing in exposure to flooding conditions, individuals from site C, the most frequently flooded site, expressed significantly higher average ADH activity when flooded than individuals from site A, a site with no history of flooding. Since ADH activity levels are not correlated with electrophoretic mobility variation in T. repens, this work supports previous suggestions that regulatory variation in enzyme activity may play a central role in biochemical adaptations to environmental stress.
摘要：
洪水导致许多高等植物中厌氧代谢的诱导。作为厌氧能源生产的重要组成部分，酒精脱氢酶（ADH）活性显着增加，以响应白三叶草的洪水，白三叶。洪水引起的ADH活性的显着个体间差异存在于T.repens的自然种群中。通过对来自75个温室饲养家庭的数据的后代-中亲回归分析了该变异的遗传基础；洪水诱导的ADH活性的估计遗传力为0.55（±0.13）。洪水诱导的ADH活性的遗传变异对该物种的生理反应和洪水耐受性有明显影响。ADH活性与乙醇产率呈正相关,表明观察到的体外活性差异表现在体内生理功能上。洪水期间具有较高ADH活性的T.repen植物具有更大的抗洪性（以洪水/未洪水生长速率时的生长速率衡量）。洪水期间ADH活性的变化占洪水耐受性变化的79％以上。根据对居住在三个不同洪水条件下的地点的人口进行的有限实地调查，来自站点C的个人，最常被洪水淹没的地方，淹没时表达的平均ADH活性明显高于来自站点A的个体，一个没有洪水历史的地方。由于ADH活性水平与白蜡笔的电泳迁移率变化不相关，这项工作支持了先前的建议，即酶活性的调节变化可能在生化适应环境压力中起着核心作用。
