Plant Diseases Flashcards
(23 cards)
Define pathogen
A biological agent responsible for an infectious disease
Define pest
An ectoparasite, like an insect or mite that affects plant health by eating plant tissue
Define parasite
A microorganism that damages plants by invading the tissues. That includes viruses
Define vector
A carrier that passes diseases between plants
What percentage of plant disease is fungi responsible for?
70%
Define biotroph
Feed directly off the cells using haustoria (a slender projection from the hyphae that penetrates the cell)
Define necrotroph
Produces enzymes or toxins that kill cells
Define hemibiotrophs
Start as biotrophs and then switch to necrotrophy
What is the basic process of a virus infecting a cell?
Attachment (binds to specific receptors on the host cell membrane) entry, un coating , replication, transcription and translation, assembly, and release (either by bursting (lysis) or budding
How many plant diseases are caused by bacteria?
80k
What are the two main categories of how bacteria invade a plant cell?
- Brute force- responsible for soft rot, secretes enzymes that degrade cell walls
- Stealth- causes leaf spots necrosis and wilting. Secrete proteins that suppress the immune system
What are some other examples of pathogens?
Oomycetes, nematodes, parasitic plants
Define plant immunity
The ability of the plants to contain the damaging effect of a pathogen or pest
Give examples of passive defense
Cuticles and wax
cell wall and lignin
bark thorns and prickles
Hydathodes
Leaf hairs and trichomes
Secondary metabolites that are released in resin
What are the three major active defenses that plants use?
Jasmonic acid response
Hypersensitive response
Systemic aquired resistance (SAR)
Define jasmonic acid response
A response to a large amount of tissue damage (such as done by predators or severe infection)
-Wounding/ herbivory
-Causes damage to chloroplasts which releases linolenic acid forme membranes to cytosol
-linolenic acid enters the peroxisomes and causes biosynthesis of jasmonic acid
- JA is activated in cytosol and turns on many defense genes
Define hypersensitive response
This is a localized response that attempts to contain a pathogen
HR triggers a swift and targeted programmed cell death (apoptosis) at the infection site to restrict spread
Define systemic acquired resistance
A whole plant molecular defense that activates large sets of genes
What is PAMP?
PAMP- triggered immunity is the oldest. Plant receptors identify PAMPs (pathogen associated molecular patterns) that are key markers of a pathogen (flagella or chitin) and this triggers a signaling cascade that leads to calcium influx, reactive oxygen species (ROS), and transcription of defense genes
What is effector- triggered immunity (ETI)?
This is newer - pathogens evolved ways to get around the first immune pathway by using effectors, molecules that block the pamp pathway. So effector triggered immunity releases molecules that block these effectors
What is the relationship between plants and pathogens?
A case of coevolution where each species exerts
What is the relationship between plants and pathogens?
A case of coevolution where each species exerts selective pressure on the other
What is the zig zag model
Jones and dangl captured this idea of plant defense with this graph - can be seen as another version of the predator prey relationship seen in ecology
