Variation in Alcohol Dehydrogenase Activity and Flood Tolerance in White Clover, Trifolium repens

Abstract

Hooding 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 interindividual variation in flood-induced ADH activity exists in natural populations of T. repens. The genetic basis of this variation was analyzed by offspring-rnidparent 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 floodedlunflooded growth rate). Variation in ADH activity during flooding accounts for more than 79% of the variance in flood tolerance. On the basis ofa 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 playa central role in biochemical adaptations to environmental stress.

Cultivar variation in response of strawberry fruit to high carbon dioxide treatments

“…13,22 Activities of these enzymes may be important in fruit tolerance to anaerobic conditions as indicated for other plant systems, eg variation in ADH activity accounted for more than 79% of¯ooding tolerance in individuals of natural populations of Trifolium repens. 23 ADH and AAT also have important roles in development of strawberry volatiles during normal ripening. 22,24 Differences in volatile accumulation under high CO 2 partial pressures may be related to naturally occurring variation in the activities of these enzymes and their isozymes during normal fruit development among cultivars.…”

Flooding tolerance and genetic diversity in populations of Luehea divaricata

“…Intraspecific differentiation has been previously reported. Chan and Burton (1992) found that seeds of Trifolium repens from a site constantly challenged by flooding presented higher flood tolerance, while seeds from a site without flooding history presented lower flood tolerance. Lessen et al (2004) showed that flooding induces genetic variation within Ranunculus reptans populations on a small spatial scale.…”

Local adaptation of the clonal plantRanunculus reptansto flooding along a small‐scale gradient

“…1997) overrides the impact of selection. A number of studies have indicated that there is genetic variation within species in all of the physiological traits mentioned above, suggesting that there is the potential for selection (Linhart & Baker 1973; Keeley 1979; Chan & Burton 1992; Robe & Griffith 1998; Lynn & Waldren 2002, 2003). Moreover, genetic differentiation in these traits has been found over a small spatial scale along flooding gradients (e.g.…”

“…2000). In Trifolium repens , seed families with higher ADH (alcohol dehydrogenase) activities during flooding had greater flood tolerance (Chan & Burton 1992), and seed families from a site without flooding history had lower ADH levels than those from a frequently flooded site. However, we are not aware of any well‐replicated study that has tested for local within‐population adaptation in response to flooding.…”