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Abstract
Constitutive chemical defenses, always expressed in the plants, and plastic defensive responses, those mobilized in response to plant injury or other cues or herbivory risk, differ in their benefits in terms of fitness for long-lived plants. Induced defenses are considered to be less expensive than constitutive preformed defenses since the cost is realized only when required. Plant defense theory predicts that, as secondary metabolism is costly for the plant, presenting effective levels of constitutive defenses and the ability of expressing efficient inducible defenses by a plant are two resource-related attributes that are not likely to be maximized at the same time. Furthermore, selective pressure favoring the expression of induced responses is likely to be lower in those lineages well defended constitutively, as they would be less subjected to herbivore attacks. A negative, non-spurious genetic correlation between constitutive and inducible defenses illustrates this classical trade-off. The existence of these evolutionary conflicts has been suggested often in the literature and sometimes reported for angiosperms, but rarely in conifers and not yet in pine trees. Besides, the emergence of this genetic constraint could be hidden by environmental factors affecting growth potential, such as nutrient availability.
Parent Publication
Citation
Sampedro, Luis; Moreira, Xoaquín; Zas, Rafael. 2012. Trade-offs between induced and constitutive resistance in two pine species: secondary chemistry, effective antiherbivore-resistance, and effect of nutrient availability. In: Sniezko, Richard A.; Yanchuk, Alvin D.; Kliejunas, John T.; Palmieri, Katharine M.; Alexander, Janice M.; Frankel, Susan J., tech. coords. 2012. Proceedings of the fourth international workshop on the genetics of host-parasite interactions in forestry: Disease and insect resistance in forest trees. Gen. Tech. Rep. PSW-GTR-240. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture. p. 125.
