response to herbicide

Definition

Target type: biologicalprocess

Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a herbicide stimulus. Herbicides are chemicals used to kill or control the growth of plants. [GOC:curators]

Herbicides are chemical substances used to kill or control unwanted plants, commonly known as weeds. They are designed to interfere with specific biochemical processes within the plant, leading to disruption of growth, development, and ultimately death. The response to herbicide is a complex biological process involving multiple pathways and cellular mechanisms.

**1. Target Site Inhibition:** Most herbicides target specific enzymes or receptors within the plant cell, interrupting crucial metabolic processes. This is known as target site inhibition.

* **Photosynthesis Inhibition:** Herbicides like glyphosate and atrazine interfere with photosynthesis, the process by which plants convert sunlight into energy. Glyphosate inhibits the enzyme EPSP synthase, which is involved in the synthesis of aromatic amino acids essential for plant growth. Atrazine blocks the electron transport chain in photosystem II, preventing the production of ATP and reducing power, leading to cellular energy depletion.
* **Amino Acid Synthesis Inhibition:** Herbicides like glyphosate, sulfonylureas, and imidazolinones interfere with the synthesis of amino acids, particularly aromatic amino acids. These amino acids are essential building blocks for proteins and other important plant molecules.
* **Lipid Synthesis Inhibition:** Herbicides like diclofop-methyl and fenoxaprop-p-ethyl interfere with the synthesis of fatty acids, which are crucial for cell membranes and other cellular structures.
* **Cell Division Inhibition:** Herbicides like trifluralin and oryzalin disrupt microtubule formation, which is essential for cell division. This leads to impaired growth and development.

**2. Plant Hormone Interference:** Some herbicides mimic or inhibit the action of plant hormones, disrupting normal growth and development.

* **Auxin Mimicry:** Herbicides like 2,4-D and dicamba mimic the action of the plant hormone auxin, leading to abnormal growth and development.
* **Auxin Inhibition:** Herbicides like picloram and triclopyr inhibit the action of auxin, disrupting normal growth patterns.
* **Ethylene Production:** Herbicides like ethephon promote the production of the plant hormone ethylene, leading to leaf senescence and fruit ripening.

**3. Oxidative Stress:** Some herbicides generate reactive oxygen species (ROS) within the plant cell, leading to oxidative stress and damage to cellular components.

* **Lipid Peroxidation:** ROS can damage cell membranes through lipid peroxidation, leading to membrane instability and leakage.
* **Protein Damage:** ROS can damage proteins, impairing their function and causing cell dysfunction.
* **DNA Damage:** ROS can damage DNA, leading to mutations and cell death.

**4. Detoxification Mechanisms:** Plants have evolved various detoxification mechanisms to cope with herbicide exposure.

* **Metabolic Transformation:** Plants can metabolize herbicides, converting them to less toxic forms.
* **Compartmentation:** Plants can sequester herbicides in vacuoles or other cellular compartments, limiting their effects.
* **Repair Mechanisms:** Plants have mechanisms to repair damage caused by herbicides, such as DNA repair.

**5. Response to Herbicide Resistance:** Some plants have evolved resistance to specific herbicides through various mechanisms, such as mutations in target sites, enhanced detoxification, or reduced uptake.

The response to herbicide is a complex and dynamic process that varies depending on the herbicide, the plant species, and environmental conditions. Understanding the underlying mechanisms of herbicide action is crucial for developing new, more effective, and environmentally sustainable weed control strategies.'
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Proteins (3)

Compounds (74)