Anonymous
Jun 5
Write short notes on mechanisms that plants use to resist phytotoxic compounds?
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Jun 5
1. Metabolic detoxification: Plants have enzymes that can modify phytotoxic compounds into less harmful forms. For example, cytochrome P450 enzymes can oxidize and detoxify herbicides.
2. Sequestration: Plants can sequester phytotoxic compounds in vacuoles or other cellular compartments to prevent them from causing damage to essential cellular processes.
3. Efflux pumps: Plants can use efflux pumps to actively transport phytotoxic compounds out of cells, reducing their concentration and toxicity within the plant.
4. Target site modification: Plants can modify the target sites of phytotoxic compounds, making them less susceptible to their effects. For example, mutations in the target site of herbicides can confer resistance to the herbicide.
5. Enhanced antioxidant defense: Plants can increase their production of antioxidants to counteract the oxidative stress caused by phytotoxic compounds. This helps to protect cellular structures and maintain normal physiological functions.
2. Sequestration: Plants can sequester phytotoxic compounds in vacuoles or other cellular compartments to prevent them from causing damage to essential cellular processes.
3. Efflux pumps: Plants can use efflux pumps to actively transport phytotoxic compounds out of cells, reducing their concentration and toxicity within the plant.
4. Target site modification: Plants can modify the target sites of phytotoxic compounds, making them less susceptible to their effects. For example, mutations in the target site of herbicides can confer resistance to the herbicide.
5. Enhanced antioxidant defense: Plants can increase their production of antioxidants to counteract the oxidative stress caused by phytotoxic compounds. This helps to protect cellular structures and maintain normal physiological functions.
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Google Gemini AI
Jun 5
Phytotoxic Compound Resistance Mechanisms in Plants
1. Detoxification Enzymes:
- Cytochrome P450 monooxygenases: Catalyze the breakdown of phytotoxins into less harmful metabolites.
- Glutathione S-transferases: Conjugate phytotoxins with glutathione, making them easier to transport and excrete.
2. Metabolic Compartmentalization:
- Plants store phytotoxins in vacuoles or cell walls, away from vital cellular processes.
- Tonoplast transporters limit the entry of phytotoxins into the cytoplasm.
3. Membrane Modifications:
- Reduced membrane permeability prevents phytotoxin entry.
- Changes in cell membrane composition can alter the binding sites for toxins.
4. DNA Repair Mechanisms:
- Nucleotide excision repair: Removes phytotoxins that damage DNA.
- Mismatch repair: Corrects errors introduced by phytotoxins during DNA replication.
5. Antioxidant Defense System:
- Enzymes (e.g., superoxide dismutase, catalase) scavenge reactive oxygen species (ROS) produced by phytotoxins.
- Non-enzymatic antioxidants (e.g., ascorbate, glutathione) neutralize ROS.
6. Hormonal Responses:
- Phytotoxins can trigger hormone responses that enhance resistance, such as the production of ethylene and jasmonic acid.
7. Induced Systemic Resistance:
- Exposure to low levels of phytotoxins can induce systemic resistance throughout the plant, priming it to respond more effectively to subsequent exposures.
8. Avoidance Mechanisms:
- Some plants avoid phytotoxins by releasing volatiles that repel insects or pathogens that transmit toxins.
- Plants may also exhibit morphological changes, such as leaf shedding, to reduce toxin exposure.
1. Detoxification Enzymes:
- Cytochrome P450 monooxygenases: Catalyze the breakdown of phytotoxins into less harmful metabolites.
- Glutathione S-transferases: Conjugate phytotoxins with glutathione, making them easier to transport and excrete.
2. Metabolic Compartmentalization:
- Plants store phytotoxins in vacuoles or cell walls, away from vital cellular processes.
- Tonoplast transporters limit the entry of phytotoxins into the cytoplasm.
3. Membrane Modifications:
- Reduced membrane permeability prevents phytotoxin entry.
- Changes in cell membrane composition can alter the binding sites for toxins.
4. DNA Repair Mechanisms:
- Nucleotide excision repair: Removes phytotoxins that damage DNA.
- Mismatch repair: Corrects errors introduced by phytotoxins during DNA replication.
5. Antioxidant Defense System:
- Enzymes (e.g., superoxide dismutase, catalase) scavenge reactive oxygen species (ROS) produced by phytotoxins.
- Non-enzymatic antioxidants (e.g., ascorbate, glutathione) neutralize ROS.
6. Hormonal Responses:
- Phytotoxins can trigger hormone responses that enhance resistance, such as the production of ethylene and jasmonic acid.
7. Induced Systemic Resistance:
- Exposure to low levels of phytotoxins can induce systemic resistance throughout the plant, priming it to respond more effectively to subsequent exposures.
8. Avoidance Mechanisms:
- Some plants avoid phytotoxins by releasing volatiles that repel insects or pathogens that transmit toxins.
- Plants may also exhibit morphological changes, such as leaf shedding, to reduce toxin exposure.
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