Week 17 Flashcards
Select all biotic factors that may be harmful to a plant.
Bacteria
Animals
Other plants
Fungi
A nonnative species can become invasive when it has no natural _____
in its new environment.
Blank 1: predators
What is the first line of plant defense against predators?
Dermal tissue
Select all physical defenses used by plants to defend against pathogens.
Trichomes on leaves
Wax coatings on stems
Bark on trees
Thorns are an example of
a physical defense mechanism.
Biotic factors that may be harmful to plants include ______.
bacteria and fungi
Plants often protect themselves against herbivores using secondary ______.
metabolites
A nonnative invasive species can become problematic due to
its lack of natural predators.
Caffeine and nicotine are both examples of ______.
alkaloids
The first line of defense protecting plants from their predators is the ______
tissue system.
Blank 1: dermal
Select all substances that act as a first line of defense and help to protect plants from water loss and attack.
Cutin
Suberin
Wax
Choose all that act as physical barriers which protect plants against invaders.
Thorns
Bark
Trichomes
Secondary metabolites can deter herbivores by (choose all that apply)
negatively affecting cellular processes in the herbivore.
binding to and inactivating proteins.
having a strong repellent odor.
What is one type of chemical defense used by plants against herbivores?
Secondary metabolites
Select all alkaloids.
Caffeine
Nicotine
Morphine
What is the first line of plant defense against predators?
Dermal tissue
The cellular effects of tannins include
inactivation of proteins.
Select all physical defenses used by plants to defend against pathogens.
Bark on trees
Trichomes on leaves
Wax coatings on stems
Many plants produce toxins that could kill any eukaryotic cell, including the plant’s cells. The plant is protected because the toxic chemicals are kept inside a ______-bound structure.
Blank 1: membrane
Match secondary metabolites to their mechanism of action.
Alkaloids
Tannins
Oils
Cyanogenic glycosides
Alkaloids- Affect cellular processes, causing, for example, over-stimulation, or sedation
Tannins- Bind to and inactivate proteins
Oils- Repel insects with their scent
Cyanogenic glycosides
-Toxic to insects when metabolized in their guts.
Plants often protect themselves against herbivores using secondary ______.
metabolites
The wound response in plants leads to the rapid production of ______ that affect the digestive enzymes of herbivores.
proteinase inhibitors
Tannins reduce the nutritional value of plant tissue by
inhibiting digestive enzymes.
As a result of the plant wound response, what molecules are produced throughout the plant?
Proteinase inhibitors
Choose the two strategies used by plants to protect themselves against the toxic chemicals they synthesize.
Sequester toxic chemical in a membrane-bound structure
Produce chemicals in inactive form, so that they are only activated in the herbivore digestive tract
Put the events of the wound response in in tomato plants in the proper order, starting at the top.
- injured leaves produce systemin
- systemin enters the phloem
- systemin transported thorughout the plant
- jasmonic acid is produced
- defense genes including proteinase inhibitor genes are activated
Plants produce proteinase inhibitors in response to
wounding.
Which of the following is a compound that appears to play a role in the wound response and is found in the bark of some plants, such as the white willow?
Salicylic acid
When a plant has been wounded, proteinase inhibitors are produced
throughout the plant.
When conducting plant experiments, scientists are careful to cut and manipulate control plants in the same way that they cut and manipulate plants receiving the test treatment. Why is this important?
To account for the triggering of the wound response
During the plant wound response,cells with a systemin receptor will synthesize _____ _____
Blank 1: jasmonic
Blank 2: acid
In addition to jasmonic acid (whose production and activity are well studied), the wound response also involves _____
acid which is found in large amounts in the bark of some plants, such as the white willow.
salicylic
As a result of the plant wound response, what molecules are produced throughout the plant?
proteinase inhibitors
Suppose a scientist is setting up a study to test a plant’s response to a virus by damaging the epidermis and then applying the virus. It would be important to set up a control in which
the plant is wounded in the same way but the virus is not added.
What are plant diseases?
As long as humans have been farming the land, plant diseases have limited production.
Plant diseases lead to a reduction in quality, yield, and value:
Reduce photosynthesis- as there are dead areas of the plant- making it smaller. Can kill the plant as well. The plant may look okay but the food for whatever reason is inedible, poisons, toxins present.
* Plants have natural defences against pathogens
* Growers can manage diseases
How do plant diseases occur?
Plant diseases don’t really occur on a wide scale in nature, really they are a result of our farming practices where we’re growing plants in monoculture. We have our genetically identical plants that are cultivated over large areas ( a monoculture). This means there’s many susceptible host plants that are in close proximity to the pathogen to invade. In nature we don’t have these monocultures, there’s a whole diversity of species and different genotypes. So even if a plant pathogen we’re able to affect one of these individual plants, it’s probably not going to be able to infect all of them. So there is a struggle to establish disease over this wide area.
_____ cause disease.
Can be difficult to determine whether the symptoms, the malformations we might see on a plant is actually caused by a disease. Could be caused by ____ factors- things like adverse weather conditions, if it’s too hot or cold etc.
Pathogens
abiotic
Symptoms of plant diseases vs signs of pathogens.
Symptoms are the visible or detectable abnormalities arising from the disease- observations on the plant itself.
Signs are the visible pathogen itself (seeing the fungus or the bacteria).
What is Chlorosis and Necrosis?
These are Chlorosis or necrotic lesions on a plant- they can be in the roots or the leaves, the fruits. Chlorosis- where there is yellowing of the plants. Necrosis- dead tissue is the brown areas. As a whole these symptoms that you can see here are known as leaf spots.
Symptoms-
Necrotic leaf spot-
this is sometimes this death is caused by the pathogen and sometimes it’s caused by the plant as a defence mechanism.
What are some signs of plant disease?
Visible structures of the pathogen- these signs are quite typical of the pathogen. Are able to aid us in diagnosis of the pathogen. Whereas the symptoms might be more general- and you may not be able to work out what’s causing the disease by just looking at the symptoms.
Fungi -
Eukaryotic Heterotrophic Hyphae Mycelium- main body made up of hyphae. Fruiting bodies Spores
Signs and symptoms include-
- Soft rot- using enzymes to degrade the tissues to extract the nutrients.
- Leaf spots/scald
- Dry rot
- Leaf curl
- Powdery mildew
- Rust
- Smut
- Mycelium
- Fruiting bodies
Fungi-like microorganisms-
Oomycota (are more closely related to brown algae and diatoms. Don't have divisions between their cells) • Eukaryotic • Heterotrophic • Branched hyphae • Thick-walled oospores • Motile zoospores
Oomycete Phytophthora infestans
Devastating pathogen of potato
Late blight
Necrosis
• Downy mildews
• Various oomycota
• “Fuzzy” or “furry” mould on leaves
Damping off- where the seedlings die.
Bacteria-
more important in tropical regions because they need high temperatures to grow then fungi etc.
What are sign and symptoms produced by bacteria
Signs and symptoms • Leaf spots • Wilts- infecting the vascular system. • Cankers • Diebacks • Rots • Galls • Scorch- a blockage where sugars are prevented from moving from the leaves to the roots. • Ooze
Viruses-
- Transmitted by vectors
- RNA or DNA ( 70% of plant viruses are ssRNA viruses)
- Protein coat
- Lipid membrane
Symptoms caused by viruses?
Symptoms • Necrosis • Mosaics • Chlorosis • Stunting • Crinkling
Nematodes and what are the signs and symptoms caused by them?
- Unsegmented small worms
- Microscopic
- Some feed on bacteria; some feed on plants
- Ecto- and endo-parasites
Signs and symptoms: • Stunting • Discolouration, decline • Dieback • Root lesions, rots • Necrosis • Chlorosis • Galls • Cysts
How to diagnose plant disease?
Koch’s postulates
• Not always easy to find out what is causing the damage
• Pathogen, pest or abiotic factor?
We can first rule out abiotic factors- so you could look at the field of your crop and you can see if different species are suffering from the same symptoms.
Pests- see if there are any visible pests on the crop- insects living on the crop etc.
