Regrowth and Alcohol Dehydrogenase Activity in Waterlogged Alfalfa and Birdsfoot Trefoil1
- A. L. Barta2
Susceptability of alfalfa (Medicago sativa L.) to waterlogging injury seriously limits its persistance and adaptability. Waterlogging injury and accumulation of ethanol under root anoxia may be causal agents which facilitate or promote infection by Phytophthora megasperma Drechsler zoospores and result in “root rot” of alfalfa.
While induction of alcohol dehydrogenase (ADH) and increased root accumulation of ethanol are general characteristics of flood-intolerant species, these parameters have not been examined in alfalfa and birdsfoot trefoil (Lotus corniculatus L.) which vary greatly in flood tolerance and Phytophthora resistance. The objective of this greenhouse study was to compare the flooding response of alfalfa and birdsfoot trefoil and determine the effect of anoxia on the induction of ADH and accumulation of ethanol in flooded roots of both species.
When flooded for 7 days, alfalfa exhibited much more severe shoot injury symptoms (wilted and yellowing leaves), reduced shoot dry weight, reduced shoot and root total nonstructural carbohydrates, and reduced rates of acetylene reduction than trefoil which is Phytophthora resistant. Induction of ADH activity was very rapid and reached similar levels in both alfalfa and trefoil. Flooding for 6 days at 22 C resulted in maximum ethanol concentration in alfalfa after which shoot injury symptoms rapidly developed. However, ethanol concentration in trefoil roots was several fold lower than alfalfa indicating that trefoil may effectively remove ethanol from the roots.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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