Chemische Verteidigung

Transcription

1 Chemische Verteidigung

2 Mechanische Abwehr

3 Hakenhaare Dornen Dornen Holz

4 Cyanogene Glykoside

5 Konstitutive (= präformierte) Abwehr

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9 Pelargonien

10 Poison Ivy (Rhus toxicodendron)

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12 O O O O O O O isoimperatorin oxypeucedanin OCH 3 OCH 3 O O O O O O OCH 3 peucedanin 8-methoxypeucedanin limonene

13 cardenolides Asclepias syriaca

14 Avoidance by horses

15 Tetraopes beetles chew the leaves and sequester the cardenolides; their red warning color aims to indicate the impalpability to birds (aposematic warning colorization)

16 Monarch butterfly Larvae

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18 A naive bluejay who has never before in his life encountered a monarch

19 Apparently programmed genetically to remove the inedible (or no food value?) wings of a butterfly, the naive bluejay does just exactly that.

20 Once the monarch has been de-winged, it swallows the monarch s body.

21 A few minutes (seconds?) after swallowing the monarch butterfly body, the bluejay begins to show a strong alarm reaction. All is not well. The feathers begin to stand on end, and it looks askance at the world.

22 The end. When the bird s gut perceived the cardiac glycosides (origin in the milkweed), its immediate protective reaction was to vomit up the gut contents.

23 Adult Chrysomelid beetle larvae

24 Clerid beetle, a carnivorous Batesian mimic

25 A Mullerian mimic, the ladybird beetle, makes its own defense chemicals, but the similarity with aposematic warning coloration of other beetles presents an advantage as the similarly-colored beetles are generally avoided by birds

26 Induzierte Abwehr

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28 Sorghum and infection by Colletotrichum graminicola

29 HO O + OH Phytoalexins: OH Apigenidin Low molecular compounds that are synthesized after exposure to microbial invasion. OH OH HO O + OH Luteolinidin

30 Hypersensitive response results in a localized cell death reaction

31 Recent insights point to the mitochondrium as central player in programmed cell death

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35 a, Disease lesion on a leaf of an empty-vector control alfalfa plant 10 days after infection with Phoma medicaginis (fungal hyphae and reproductive structures (pycnidia) are stained blue against the background of the leaf that has been cleared of chlorophyll). b, Lesion of identical age on a plant that had been transformed with a grapevine stilbene-synthase gene under control of the cauliflower mosaic virus 35S promoter. Such plants constitutively accumulate a glucoside of the novel phytoalexin resveratrol (structure indicated) and exhibit vastly reduced fungal development.

36 c, Lesions of Phoma medicaginis 5 days post-inoculation on leaves of alfalfa plants transformed with an empty-vector control construct. d, Lesions of identical age on plants constitutively expressing an alfalfa IOMT transgene from the 35S promoter. The endogenous IOMT genes, and the other genes of the isoflavonoid pathway, are not constitutively expressed, but are induced after fungal infection. The high expression of IOMT during the early stages of the response to the fungus results in more rapid production of the endogenous phytoalexin medicarpin (structure indicated) and consequent reduction in disease severity.

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41 Salicylsäure und Thermogenese

42 Fig. 3. Diversity of plant oxylipins formed in response to biotic aggressions. After mobilization by lipid acyl hydrolases (LAHs) from structural lipids, free fatty acids can be oxidized by at least three primary enzymatic systems (shown in color boxes), the best known being the lipoxygenase (LOX) pathway. LOXs generally introduce molecular oxygen onto carbon 9 or 13 (and are referred to as 9- or 13-LOX) in C18 unsaturated fatty acids, leading to 9- or 13-specific derivatives. LOX-generated fatty acid hydroperoxides may enter sub-branches, generating antimicrobial, cytotoxic, or signaling compounds. The profile of oxylipins formed depends on the enzymatic equipment of each plant species and on the type of stress that is encountered. In addition, a series of nonenzymatically derived, prostaglandin-like compounds (phytoprostanes) are formed under oxidative stress upon wounding or pathogen attack. AOS, allene oxide synthase; DES, divinyl ether synthase; EAS, epoxy alcohol synthase; FA, fatty acid; HPL, hydroperoxide lyase; LOX, lipoxygenase; a-dox, a-dioxygenase.

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44 Chemische Bomben

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46 Phytohormone

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48 Nyctinastische Bewegungen

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