Plant responses to Abiotic Stress & Herbivory

Physical Defences to protect plants from herbivores

• Thorns, barbs, spikes, stings

• Spiny leaves, hairy leaves

• Inedible tissue

What chemicals do plants produce in defence to herbivory?

• (Tannins)

• Alkaloids

• (Terpenoids)

• Pheromones

Alkaloids

Very bitter-tasting, or toxic nitrogenous compounds, e.g. caffeine, cocaine, nicotine, morphine

• Affect metabolism of animals, can poison them, toxic

Pheromones

Chemicals made by an organism which affects social behaviour of other members of the same species

• Produces signals to nearby plants of the same species that they’re under attack from herbivores, triggering other defences e.g. callose production

Volatile Organic Compounds (VOCs)-

Can act as pheromones between plants & other organisms; diffuse in air & around plant

• Plants use these chemical signals to defend themselves; begin to produce VOC before attack

Use it to attract a herbivorous insect’s natural predators

Plants folding in response to touch

Scientists think it frightens off larger herbivores, & dislodges small insects that have landed on the lead