Plant defenses Flashcards
different types of ecological interactions
Mutualism (+/+)
Commensalism (+/0)
Competition (-/-)
Predation (herbivory, parasitism, predation)
Symbiosis = mutualism, commensalism, parasitism
Explain why plants need to be able to defend themselves. What are they defending themselves
against (pathogens and herbivores)?
Things have been around that eat plants as long as plants have been around (coevoltuion) so plants had to evolve to defend themselves against these harmful interactions. They are defending themselves against pathogens like viruses, bacteria, and parasitic fungi, as well as herbivores like pests and mammals
How could you distinguish between a pathogen and an herbivore?
herbivores come and munch on the leaves of plants and are not really effecting the plant on a physiological level, where pathogens infiltrate the plants and typically prevent ability to transport nutrients by infecting cambium layer
What can we learn about plant defenses by studying invasive species like the chestnut blight and
the woolly adelgid?
We can learn about how plants are impacted by these invasive species and see what defenses they lack that allowed them to be susceptible to this attack. Plants evolve indecible defenses based on their environment, so they are uniquely vulnerable to invasive species from other environments because they are defenseless against them
Describe the differences between constitutive defenses and inducible defenses. Provide
examples of each.
Constitutive defenses are preexisting, including thorns or hairs with toxins where inducible defenses are how plants respond to an attack and include sending signals to genes to grow thorns or to make toxins
How does the HR response work?
Hypersensitive response prevents the spread of pathogens in plants by closing the stomata, producing toxins targeted to the pathogen, reinforcing cell walls, and causing rapid apoptosis of damaged and surrounding cells (programmed cell death)
Explain how apoptosis is important against pathogens.
Apoptosis is the programmed cell death that occurs when damaged or infected cells are killed off by the plant in order to avoid spread of pathogen. This occurs through the orderly release of nucleares that hop up genetic material and proteases that chop up proteins
Explain why the systemic acquired response is important.
Systemic required response is important because it is an inducible defense against pathogens and results in the expression of pathogenesis -related genes (protect from further infection)
Explain how SAR works.
HR sends the SAR signal that causes PR genes (pathogenesis-related genes) transcription which protects the plant from further infection
Explain the role of systemin and Jasmonic acid in plant responses to herbivores.
System in a peptide hormone for wound response and is released from damaged cells, which sets off signal transduction pathway, travels via phloem, and causes target cells to produce jasmonic acid. Jasmonic acid causes upregulation of different gene products that prevent the plant from being eaten
How and why do trees “talk” to each other.
Trees are able to talk to each other by releasing volatile compounds into the air when they are attacked. Other plants can detect these compounds and know to ramp up their defenses. This cooperation among species is very important to an ecosystems survival
What is one reason chili peppers evolved capsaicin
To prevent mammal herbivory while allowing birds to eat them because they swallow them whole and will poop them back out with a bunch of nutrients where they can grow again
