Annals of Botany 37: 463-471, 1973
© 1973 Annals of Botany Company
RESEARCH-ARTICLE |
An Analysis of the Mussell and Morré Quantitative Bioassay for Polygalacturonases using Pectate trans-eliminase from Erwinia atroseptica
Department of Botany and Plant Technology, Imperial College London, S.W. 7, U.K.
Received: 3 July 1972
The Mussell and Morré method for estimating the activity of chain-splitting pectic enzymes was tested with sections of parenchyma from cucumber fruit and potato tubers. It proved to be a very sensitive test for the pectate trans-eliminase of Erwinia atroseptica, between 10 and 100 times as sensitive as a viscometric method based on degradation of polypectate. Loss of fresh weight was readily detected within a few minutes after immersion in enzyme solution and continued until the section of tissue had lost coherence. For some time after immersion, loss of weight was mainly due not to loss of cells from the surface of the section but to loss of water and solutes, presumably because of the effect of the trans-eliminase in decreasing the permeability of the protoplasts. In the later stages loss of cells became more important. Potato sections lost weight at about half the rate of cucumber sections but the rate of increase of absorbance at 235 nm of the ambient solution was about a third higher for potato than for cucumber. Potato sections lost electrolytes much more rapidly than did cucumber sections. These differences probably reflect, at least in part, the much higher water content of cucumber sections.
The advantages of the Mussell and Morré method are its sensitivity and the fact that the natural substrates of chain-splitting enzymes can be used for assessing activity.