Loss of Suberin from Bark tissue rotted by Armillaria mellea

Abstract

SUBERIZED tissue has for a long time been regarded as among the most resistant of plant tissues to fungal decay. Cork can be virtually immune from breakdown1,2, and the production of cork barriers is a common host reaction to fungal infection3. Nevertheless, there can be little doubt that suberin must eventually be degraded by micro-organisms in the soil and litter; similarly, it is known that several fungi are capable of penetrating suberized barriers. Among these is Armillaria mellea, which was shown by Thomas4 to be able to penetrate directly through the bark of host roots. Although this penetration was largely mechanical, Thomas reported some degradation of the cork layers in advance of the fungal hyphae. This suggestion of enzymatic breakdown of the cork layers has been largely discounted by later authors5,6.