Summary
Plants use thorns, toxins, jasmonate signalling and systemic acquired resistance against herbivores and pathogens.
In depth
Constitutive: waxy cuticles, thorns, lignin, latex. Inducible: jasmonic acid signalling to produce proteinase inhibitors, salicylic acid for systemic acquired resistance, and volatile signals to neighbours. Hypersensitive response sacrifices cells to contain pathogens.
Wounded leaves send electrical and chemical signals through the plant. Volatile methyl jasmonate can prime neighbouring plants. Specialised cells in glandular hairs store toxins.
Example: plants of the mustard family release mustard oils when damaged.
Physical defences include trichomes, waxes, spines and thick walls, and chemical defences include toxins and repellents. Induced responses involve wound signals (systemin, jasmonate) that spread through the plant, and volatile compounds that attract predators of herbivores (maize releases chemicals that draw parasitic wasps) or warn neighbours. Systemic acquired resistance (SAR), driven by salicylic acid, prepares the whole plant after local infection.
The hypersensitive response involves rapid cell death around the infection to block spread. Plants also use RNA silencing against viruses. Breeders use resistance genes, and integrated pest management uses defences. Some defences have human uses: capsaicin, caffeine, nicotine, and pyrethrins.
Frequently asked questions
What is Plant Defence Responses?
Plants use thorns, toxins, jasmonate signalling and systemic acquired resistance against herbivores and pathogens.
Which area of biology covers Plant Defence Responses, and how advanced is it?
Plant Defence Responses is one of the 56 topics in Plant Biology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Plant Immunity Receptors, Stomata, Plant Hormones.
Why does Plant Defence Responses matter?
Understanding defences helps to breed disease-resistant crops and reduce pesticide use.
Can you give an example of Plant Defence Responses?
Tomato leaves release proteinase inhibitors after caterpillar damage.
What should I learn before Plant Defence Responses?
Work through the Beginner topics in Plant Biology first, such as Plant Kingdom, Photosynthesis, Chlorophyll, then return to Plant Defence Responses. Advanced topics assume the Intermediate vocabulary.
What topics are related to Plant Defence Responses?
The closest topics to Plant Defence Responses are Plant Immunity Receptors, Stomata, Plant Hormones, Roots. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Plant Defence Responses?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Plant Defence Responses. To practise the whole of Plant Biology, use the Plant Biology quiz.
How is Plant Defence Responses different from Plant Immunity Receptors?
Plant Defence Responses: Plants use thorns, toxins, jasmonate signalling and systemic acquired resistance against herbivores and pathogens. Plant Immunity Receptors: Surface and intracellular NLR receptors detect pathogen molecules and trigger the hypersensitive response. Read both side by side and note what each one explains.
How should I study Plant Defence Responses step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Plant Immunity Receptors and explain the difference aloud. Finally, take the Plant Biology quiz and come back to this page for any question you miss.