Glucanohydrolase enzyme activity in embryos of Scots, Corsican and lodgepole pines infected <i>in vitro</i> with <i>Heterobasidion annosum</i>

The oecurrenee and .lecumulation of /J-1, 3-glucanase and chitinase in seedling roots of spruce {Picea ahies) following challenge by the root-rot pathogen Heterobasidion annosum were studied. Chitinase activity inereased 2-3 fold following inoculation, whereas no signifieant inerease in the activity levels of glucanasc was recorded during infection. With TEM immunogold labelling, the enzymes were localized in protein aggregates in host tissues and in the cell walls of intercellular hyphae. Gold particles were sparse and irregularly distributed within host-cell walls. Only minor labelling was observed on hyphaf walls coated with electron-dense materials. The labelling intensity increased with infeetion time and was always higher than in non-infected seedling roots. Wlien this experiment was repeated using root samples inoeulated with the saprophyte Phlebiopsis gigantea, a similar labelling pattern was obsei-ved. The cross reactivity of antisera raised .against sugar-beet ehitinase and glucanase with spruceroot enzyme extracts was demonstrated using dot-blot assays and ELISA.U. S.

“…A similar observation was made by NsOLOMO and WOODWARD (1994) using Pinus sylvestris. A similar observation was made by NsOLOMO and WOODWARD (1994) using Pinus sylvestris.…”

Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Immunocytochemical localization of pathogenesis‐related proteins in roots of Norway spruce infected with Heterobasidion annosum

Asiegbu

Denekamp

Daniel

et al. 1995

“…Accumulation of chitinase was also less defined in P. sylvestris than the other two species (NSOLOMO and WOODWARD 1994). In the field, young pines are all generally regarded as susceptible to infection and killing by H. annosum, although resistance to killing increases with age (HODGES 1969).…”

Section: Discussionmentioning

confidence: 99%

“…V. R. Nsolomo and S. Woodward ' : 1994). Moreover, recent studies with young fully differentiated aseptically grown seedlings have proven valuable in determining the development of resistance mechanisms in Norway spruce inoculated with necrotrophic pathogens, such as Heterobasidion annosum (ASIEGBU et al 1993(ASIEGBU et al , 1994(ASIEGBU et al , 1995 and Pythium dimorphum (BORJA et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Histological and histochemical detection of defence responses in pine embryos challenged in vitro with Heterobasidion annosum

Nsolomo

Woodward

1997

Self Cite

Embryos of Pinus sylvestris, Pinus nigra var. maritima and Pinus contorta were inoculated in vitro with Heterobasidion annosum and the histology and histochemistry of the host response determined. Three days after challenge, intercellular penetration of hyphae through the epidermis and into the cortex of the host species had occurred. In cells close to the invading hyphae, cell walls became thickened in all three pine species. Lignification and suberization of cell walls in the cortex was detectable in P. nigra var. maritima and P. contorta, but not in P. sylvestris. Moreover, cells in the cortex of P. nigra var. maritima and P. contorta became occluded with dense deposits staining positively for phenolic and lipidic materials. Starch grains had accumulated in host cells close to sites of penetration by day 3, and levels appeared to increase by day 6, except for tissues where heavy mvasion by H. annosum had occurred. Host responses intensified between 3 and 6 days after challenge. By day 6, however, the pathogen had penetrated as far as the stele and into the developing xylem vessels. Nine days after challenge, host tissues contained abundant intra-and inter-cellular hyphae, causing severe disruption and disintegration of all tissues. The utility of such in vitro systems in studies on the resistance responses of conifers to challenge with fungal pathogens is discussed.

“…Other in vitro systems using differentiated host tissues have also proven useful in the study of host resistance and host-pathogen interactions in forest tree pathology (DINER and MoTT 1982;GRAY and AMERSON 1983;NSOLOMO and WOODWARD 1994;SPANOS 1995). Seiridium cardinale causes a serious canker disease of Cupressus species, which results in dieback of branches and, eventually, death of the whole tree.…”

Section: Introductionmentioning

confidence: 99%

Responses of Cupressus and Chamaecyparis callus tissues to inoculations with Seiridium cardinale

Spanos¹,

Woodward

1997

Self Cite

Inoculations of callus generated from micropropagated shoots of Cupressus sempervirens, Cupressus macrocarpa, Cupressus torulosa and Chamaecyparis lawsoniana showed that callus of species resistant or relatively resistant to Seiridium cardinale supported significantly less surface growth of the pathogen than callus of susceptible species. In dual cultures of Cupressus sempervirens or Cupressus torulosa callus with S. cardinale, inhibition of fungal growth toward^s the callus was correlated with known field resistance of these host species. Lignification, accumulation of polyphenohcs and possible suberization of cell walls were detected in inoculated callus. This response was also correlated with known field resistance of the tested host species.