Canadian Forest Service Publications
Cytochemical aspects of cellulose breakdown during the infection process of rubber tree roots by Rigidoporus lignosus. 1991. Nicole, M.; Benhamou, N. Phytopathology 81(11): 1412-1420.
Issued by: Laurentian Forestry Centre
Catalog ID: 16545
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An exoglucanase purified from a cellulase produced by the fungus Trichoderma harzianum was bound to colloidal gold and used for ultrastructural detection of cellulosic β-(1-4)-D-glucans in root tissues of rubber trees (Hevea brasiliensis) infected by the white rot root pathogen, Rigidoporus lignosus. Large amounts of β-1,4-glucans were found in cell walls of healthy roots, except in suberized walls that were not labeled. Gold particles were absent in the fungal wall inside rhizomorphs and in infected host cells. In infected roots, cell wall degradation occurred both close to and at a distance from hyphae, causing variable decaying patterns. Few gold particles or absence of labeling were observed in degraded phellem ad phloem cell walls. In xylem vessel elements, labeling did not occur over incompletely digested areas of the S2 layer of secondary walls. During pit penetration by hyphae, degraded primary walls and the S1 layer of secondary walls were devoid of gold particles. The present cytochemical data provide evidence for cellulose degradation in roots of rubber trees infected by R. lignosus They demonstrate indirectly the implication of cellulases in the decay process and give more insight into the role cellulose degradations plays in white rot pathogenesis by R. lignosus.