Defensive compounds, chemical, plant

All these data support the idea that QA may function as chemical defense compounds. We also tested whether this chemical defense is relevant for the survival of a lupin plant. Lupins offer a unique chance to explore this question experimentally plant breeders have selected "sweet" varieties, which have a very low alkaloid content. These varieties can be compared to semi-bitter or bitter ones. We have grown Lupinus albus strains that differ in their alkaloid content in our experimental garden and greenhouse and have monitored their susceptibility to attack by plant pests. As can be seen from Figure 2, "sweet" lupins are preferentially eaten by rabbits (Cuniculus europaeus) or are infested by aphids (Aphidae) or leaf miners (Agromyzidae). Literature data also support the assumption that alkaloid-rich lupins are much more resistant to plant pests than "sweet" varieties (30-32). We conclude therefore, that QA are indeed important for the fitness of a lupin plant and that they constitute a major part of its chemical defense system, in which... 

Secondly, plants are masters of chemical defense, with a fascinating ability to produce a high diversity of chemical defense compounds, also known as secondary metabolites or allelochemicals [1-17]. Chemical defense involves macromolecular compounds, such as diverse defense proteins (including chitinase [against fungal cell... 

Monarch butterflies t.g., Danaus plexipus) combine two sets of natural compounds. Larvae feed on plants rich in cardiac glycosides and use them as chemical defense compounds. Adult butterflies visit plants with PAs, where they collect PAs that are converted to pheromones or transferred to their eggs 4,17,31,33,361,515). A similar PA utilization scheme was observed with larvae of the moth Utetheisa ornatrix 367,516), where the compounds were shown to be deterrent for spiders and birds 225, 525). The chrysomelid beetle Oreina feeds on PA-containing plants, such as Adenostyles, and stores the dieUuy PAs in the defense fluid 463,524). 

C23H38N2O5, Mr 422.47, amorphous solid. Beet army-worm caterpillars supply their plant host with a suicide weapon called V. (induced chemical defense in plants). V. is the A( -( 17-hydroxylinolenoyl) derivative of L- "glutamine. When some plants, such as com, are injured by the caterpillar s feeding, V. in damaged tissues signals the plant to emit volatile compounds that attract wasps, the caterpillar s natural enemy. V. appears to be a natural product of the caterpillar, rather than of the plants. 

Polyphenols are considered secondary metabolites of plants involved in the chemical defense of plants against predators and in plant-plant interactions. Polyphenols are found in virtually all families of plants, and comprise up to 50% of the dry weight of leaves. The main activity related to phenolic compounds is antioxidant activity. In addition to their strong antioxidant activities, plant polyphenols are known to possess other activities including antibacterial, chemopreventive, UV-protective, anticancer, and anti-inflammatory effects, act as detoxifying agents against heavy metals, and have myriad other bioactivities that could potentially be exploited for application in functional foods. ... 

While secondary metabolites of plants and animals have been the subject of many chemical investigations, their associations and roles in their host organism are at times controversial this is particularly so, when insufficient observations exist. Nevertheless, natural products provide fruitful areas of research [69]. There is little doubt that chemical defense against predators is an important aspect of survival. In the marine environment, early observations of nudi-branch- sponge relationships were reported and those relating to isocyano compounds are summarized in Table 6. 

Lubchenco J (1978) Plant species diversity in a marine intertidal community importance of herbivore food preference and algal competitive abilities. Am Nat 112 23-39 Lumbang WA, Paul VJ (1996) Chemical defenses of the tropical green seaweed Neomeris annulata Dickie effects of multiple compounds on feeding by herbivores. J Exp Mar Biol Ecol 201 185-195... 

Cornell HV, Hawkins BA (2003) Herbivore responses to plant secondary compounds a test of phytochemical coevolution theory. Am Nat 161 507-522 Cronin G (2001) Resource allocation in seaweeds and marine invertebrates chemical defense patterns in relation to defense theories. In McClintock JB, Baker BJ (eds) Mar Chem Ecol. CRC, Boca Raton, FL, pp 325-354... 

A prominent characteristic of most true bugs is their use of defensive chemicals produced in specialized scent glands, usually found in the abdomen in im-matures, and in the metathorax in adults. However, this pattern is not absolute species that feed on poisonous plants from which they sequester toxic chemical defenses tend to have reduced or modified glands [8,26-28]. Many of these species are also aposematic, vividly advertising their toxicity to would-be predators. The defensive chemistry of bugs has been the subject of a number of reviews [4,6,8,9,12,29,30] and will only be summarized here, with a focus on compounds with interesting or unusual chemistry. 

There are numerous other examples of plants, insects, large herbivores, and other organisms playing synergistic roles in nature s balance. Multiple functions are typical of plant compounds and do not contradict in any way their main role as chemical-defense and signal-induction compounds. A trait that serves multiple functions in a given plant or animal is more likely to survive the rigors of natural selection. 

Herbivores select certain plant species or parts and reject others. Plant defenses determine food choices as much as nutritional value does. Plants can defend themselves mechanically as with thorns, hairs, waxes, or structural fibers, and chemically with secondary plant compounds. Mammals have had to cope with plant defenses since they adapted to an herbivorous lifestyle approximately 85-100 millions years ago (Archibald, 1996). 

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