Resistance of graft-compatible and graft-incompatible Pseudotsuga menziesii rooted cuttings to Phellinus weirii
1994
Entry, J.A. (Oregon State University, Corvallis, OR.) | Vance, N.C. | Copes, D.L.
One-year-old rooted cuttings taken from 23- and 26-year-old graft-compatible and graft-incompatible Pseudotsuga menziesii (Mirb.) Franco were inoculated with one of three isolates of Phellinus weirii. After 20 months in a greenhouse, infection frequency and severity were significantly greater in the graft-incompatible cuttings. Cellulose concentration in the root tissue was higher in graft-incompatible than graft-compatible cuttings. Concentrations of lignin, phenolic compounds, and tannins were higher in graft-compatible than graft-incompatible cuttings. Cellulose concentration had a positive linear correlation (r2 = 0.84) with the P. weirii infection rating. The concentration of phenolic compounds and lignin in secondary root tissues was negatively correlated with the infection rating (r2 = 0.73 and 0.84, respectively). The lignin/cellulose and phenolic/cellulose ratios were negatively correlated with the infection rating of P. weirii infection in a linear relationship (r2 = 0.82 and 0.77, respectively). White-rot fungi cannot use tree defense compounds, such as lignin and phenolics, as the sole energy source; an alternate energy source is necessary to degrade these compounds. The lignin/cellulose and phenolic/cellulose ratios in the roots may be important measurements to explain the host-pathogen response of P. weirii infection
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