Systemic induction of phloem secondary metabolism and its relationship to resistance to a canker pathogen in Austrian pine.
The mechanisms and conditions affecting expression of systemic induced resistance (SIR) in pine are not clearly understood. Two hypotheses were tested here: that SIR against a pathogen induced by either a pathogen or an insect involves coordinated shifts in phloem secondary metabolism; and that fertility affects the production of these compounds. To test these hypotheses, a tripartite system was used comprising Austrian pine (Pinus nigra) grown under three different fertility regimes, the fungal pathogen Diplodia pinea, and the defoliator Neodiprion sertifer. Fungal induction led to systemic accumulation of lignin, phenolic glycosides and stilbenes, whereas insect defoliation led to an increase in germacrene D concentration in branch phloem. Fertility affected the concentrations of only the phenolic glycosides. Multivariate analyses showed coregulation of compounds within at least three consistent groupings: phenolic glycosides, stilbenes and monoterpenes. As groups and as individual compounds, accumulation of phenolic glycosides and stilbenes was negatively correlated with disease susceptibility. The experimental manipulation of the phenolics and terpenoids metabolic networks achieved in this study by biotic induction and changes in nutrient availability suggests that lignin, phenolic glycosides and stilbenes are important biochemical factors in the expression of SIR against the pathogen in this system.
Wallis
C
C
Department of Plant Pathology, The Ohio State University, 201 Kottman Hall, 2021 Coffey Road, Columbus, OH 43210, USA; Departments of.
Eyles
A
A
Department of Plant Pathology, The Ohio State University, 201 Kottman Hall, 2021 Coffey Road, Columbus, OH 43210, USA; Departments of.
Chorbadjian
R
R
Entomology.
McSpadden Gardener
B
B
Plant Pathology and.
Hansen
R
R
Agricultural Engineering, The Ohio State University/Ohio Agricultural Research and Development Center, 1680 Madison Ave, Wooster, OH 44691, USA.
Cipollini
D
D
Department of Biological Sciences, Wright State University, 208 Biological Sciences Building, 3640 Colonel Glenn Hwy, Dayton, OH 45435, USA.
Herms
D A
DA
Entomology.
Bonello
P
P
Department of Plant Pathology, The Ohio State University, 201 Kottman Hall, 2021 Coffey Road, Columbus, OH 43210, USA; Departments of.
D000704:Analysis of Variance; D000818:Animals; D016000:Cluster Analysis; D005247:Feeding Behavior / Q000502:physiology; D054884:Host-Pathogen Interactions / Q000276:immunology* / Q000502:physiology; D006927:Hymenoptera / Q000502:physiology; D010636:Phenols / Q000378:metabolism*; D052585:Phloem / Q000378:metabolism*; D028223:Pinus / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology / Q000469:parasitology; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D025341:Principal Component Analysis; D013729:Terpenes / Q000378:metabolism*
D010636:Phenols; D013729:Terpenes