Constitutive defense

Toth G, Karlson M, Pavia H (2007) Mesoherbivores reduce net growth and induce chemical resistance in natural seaweed populations. Oecologia 152 245-255 Toth GB, Langhamer O, Pavia H (2005) Inducible and constitutive defenses of valuable seaweed tissues consequences for herbivore fitness. Ecology 86 612-618... 

Vulnerability of prey to attack is positively related to the abundance of predators.7 Constitutive defenses require resources to synthesize, maintain, and store (plus other potential costs mentioned above) even when consumers are absent and the benefits of protection are not realized. Hence, the ODT predicts that allocation to constitutive defenses should be kept low when predators are absent as a means to reduce the costs of defenses when the benefits of protection are not being realized. However, once predators have been detected and tissues become vulnerable to attack, the allocation to defenses should be increased. The induction of higher levels of defenses is thought to be an adaptation to minimize the cost of defenses until costs can be offset by the benefits of protection.100,151... 

It is generally believed that in condition where herbivory is regularly expected, constitutive defense is more adaptive, whereas in condition where herbivory is expected only once in a while, it is better for plants to produce defense substances when plants are damaged by herbivory, and when there are no herbivores, it is better to invest resource to plant growth rather than defense. This idea is supported by field experiments using plant disabled to induce defense substance by gene modification techniques, and comparing seed production between plant deficient in induction and the control type.123... 

Some components of resistance are present in healthy plants and therefore are part of a constitutive defense other components are induced and formed following contact between the pathogen (or its products) and the host and therefore are parts of an active defense. The total defense is the sum of constitutive and active components. Many groups of chemicals function in both constitutive and active... 

Cotton tissues also may contain 1-3% flavonoid glucosides, most of which contain ortho-dihydroxyphenolic groups ( ). Additional quantities of flavonoid glucosides are formed Tn response to infection. These compounds are important in constitutive defense against insects, but their importance in the resistance of cotton to... 

Increased resistance to necrotrophs also could result from changes that increase antibiotic efficiency. Other approaches for these pathogens should aim at increasing constitutive defenses. Such things as higher tannin and lignin concentration, thicker cuticle structure, and increased suberization would be expected to improve resistance. 

Three 2a-methyl-perhydro-9b-azaphenalenes that constitute defensive substances of ladybird beetles were synthesized recently (cf. Vol. 7, p. 79), and an alternative synthesis has now been described (Scheme 2). The perhydrobora-phenalene (32) that was employed earlier to prepare unsubstituted perhydro-azaphenalenes (cf. Vol. 6, p. 101) was converted into the enamine quaternary ammonium salt (33) and thence into the allylamine (34). The allylamine epoxide was used to prepare ketone (36), which provided an efficient route to precoc-cinellin (35) by means of a Wittig reaction the same ketone was involved in the earlier synthesis of the alkaloid. 

Hence, these oxidative enzymes have the potential to chemically destroy a variety of essential or limiting amino acids (e.g. arginine, cysteine, histidine, leucine, lysine, methionine, serine, tryptophan, and tyrosine) (27). In addition, linoleic acid, another essential dietary component (27) is destroyed. These reactions (Figures 1 2) represent the activation of constitutive defenses and nutrients to potent antinutritive agents. 

Cutting up leaflets of Lupinus polyphyllus induces a rapid increase in quinolizidine alkaloids of up to 400% within 2.5-4.0 h. This response occurs under a variety of conditions and is neither a constitutive defense nor the usual type of induced response (Wink, 1983a). 

Constitutive defense Continuous production of defense compounds Cost effective, if plant is continuously under herbivore attack... 

Neither capsidiol nor glutinosone could be detected in healthy tissues. According to Bohlmann et al. (2002) . it is conceivable that capsidiol contributes not only to an inducible defense against pathogens, but also to a constitutive defense in an organ-specific manner in some species of Nicotiana Constitutive expression of 5-epi-aristolochene synthase (EAS) and capsidiol accumulation could not be observed in shoots of N. attenuata, but enzyme transcripts were induced by feeding of Manduca sexta, the tobacco homworm. However, EAS was expressed constitutively in roots of this N. species and N. sylvestris Spec. Comes. 

---