Lec%2076%20Plant%20behavior - Plant Behavior: Plant...

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1 André Kessler 15 Apr 2009 Plant Behavior : Plant Responses to biotic stress herbivorous insects (26%) predaceous and saprophagous insects (31%) o t h e r i n v b a s ( 1 5 % ) plants (22%) 4% vertebrates protozoa 2% DIVERSITY The BioScape in terms of biomass Classical defense theory Ehrlich and Raven (1964)— chemical coevolution between plants and insects Insect attack results in selection for plant chemical counterattack…plant resistance results in selection of insects able to detoxify specific compounds… Chemical “arms race” Plant taxa “specialize” on particular chemistry Insects lose ability to detoxify other chemicals Ehrlich and Raven (1964). Butterflies and Plants: A study of Coevolution. Evolution 18: 586-608 Paul R. Ehrlich Peter Raven Wild tobacco Nicotiana attenuata (Solanaceae) Nicotine (Alkaloid) Manduca quinquemaculata
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2 Piper sp. (Piperaceae) Piperine, Chavicine (Alkaloids) – activating TRPV 1 ion channel Eois sp. © Florian Bodner Common Milkweed Asclepias syriaca (Asclepiaceae) Cardenolides (Steroids, terpenoid lipids) Danaus plexippus Cannabis sativa (Cannabaceae) Tetrahydrocanabinol (THC)(aromatic terpenoid) Wild Mustard Sinapis arvensis (Brassicaceae) Mustardoil bomb Glucosinolates + Myrosinase (thiocyanate, isothyocyanate, nitril) Pieris brassicae Plant resistance Direct Defense Indirect Defense Tolerance Traits that reduce herbivore/pathogen survival, reproductive output or preference for a plant – from the herbivore’s/pathogens point of view Traits that decrease the negative fitness consequences of attacks – from the plant’s point of view Plant defense …reducing damage… ..or increasing tolerance… Direct defense Physical Thorns, Spines and Prickles Silica accumulation Plant traits that reduce accessibility, palatability and digestibility of plant tissue and therefore decrease the negative fitness consequences of attack Apocynaceae Roseceae Cactaceae, Euphorbiaceae Poaceae
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3 Direct defense Chemical - Primary metabolites (cellulose) - Toxic compounds (alkaloids, terpenoids, phenolics) - Anti-digestive compounds (PI) - Anti-nutritive proteins (PPO) Chemical/physical - Exudating trichromes - Stinging hairs of Urtica - Etc. Stinging nettle ( Urtica dioica ) Silica accumulation Formic acid Histamine (irritates skin) Acetylcholine (burning sensation) Serotonin (encourage other two compounds) Indirect defenses Plant traits that attract predators and parasitoids of herbivores and increase the carnivore’s foraging success and thereby facilitate top-down • Food (extrafloral nectaries, food bodies) • Shelter (hollow stems, special organs) Myrmecodia tuberosa (Rubiaceae) Macaranga tanarius (Euphorbiaceae)
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Lec%2076%20Plant%20behavior - Plant Behavior: Plant...

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