Abstract
Cucumber (Cucumis sativus) seedlings grown at 30oC differed in morphology from those grown at 20oC. Among these morphological changes, cell separation of the root cortex at 30oC was conspicuous. We previously reported the involvement of ethylene in the cell separation phenomenon (the annual meeting of the Botanical Society of Japan, 2002). The present study focused on changes in the cell wall sugar composition and in the activity of cell wall degrading enzymes. Analysis of root cell wall components revealed that at 30oC, the pectin and cellulose fractions significantly increased but that the average molecular mass of pectic polysaccharides greatly decreased. A kinetics study of polygalacturonase suggested that its activation energy is altered a certain temperature. From these results, a possible mechanism for the 30oC-induced cell separation is discussed in relation to effects of ethylene and polygalacturonase activity.
