"Plant defense against herbivory or host-plant resistance (HPR) is a range of adaptations evolved by plants which improve their survival and reproduction by reducing the impact of herbivores."
The ways in which plants respond to various stressors, such as drought, salt, extreme temperatures, and pests/pathogens.
Abiotic stresses: This refers to stress factors in the environment that are not related to living organisms, such as drought, salinity, heat, cold, and UV radiation.
Reactive oxygen species: These are molecules that can cause cellular damage and are produced as a result of abiotic stresses. Plants have defense mechanisms to manage ROS levels.
Gene expression: Changes in gene expression are responsible for many of the responses that plants exhibit when subjected to stress. Understanding this process is essential for understanding stress responses.
Hormones: Plants produce various hormones to regulate growth and development, and these hormones are also involved in stress responses.
Signal transduction: This refers to the process of converting an external stress signal into an internal cellular response. Understanding how this process works is critical for understanding stress responses.
Photosynthesis: Environmental stress can have a profound effect on a plant's ability to carry out photosynthesis, which is the process by which plants convert sunlight into energy.
Antioxidants: These are molecules that can help protect plants from the damaging effects of ROS.
Molecular chaperones: These are proteins that help maintain proper protein folding and function, which is critical under conditions of stress.
Plant-microbe interactions: Certain microbes can help plants cope with stress, and understanding these interactions can be important for developing plant-based solutions to environmental stresses.
Epigenetics: This refers to changes in gene expression that occur without changes to the underlying DNA sequence. Epigenetic changes can play an important role in stress responses.
Nitrogen fixation: Certain plants are able to "fix" nitrogen from the air, which can be an important source of nutrients under conditions of abiotic stress.
Carbon metabolism: Understanding how plants utilize and redistribute carbon under stress conditions is important for understanding stress responses and developing stress-tolerant plants.
Drought stress response: A response to lack of water availability that triggers stomatal closure, accumulation of solutes, and changes in gene expression, among other adaptive mechanisms.
Heat stress response: A response of plants to high temperatures that includes changes in gene expression, membrane fluidity, photosynthesis, and antioxidant systems.
Cold stress response: A response of plants to low temperatures that includes changes in the expression of cold-responsive genes, lipid metabolism, and freezing tolerance.
Salt stress response: A response of plants to high salt concentrations in the soil or water that triggers ion homeostasis, osmotic adjustment, and changes in gene expression.
Metal toxicity response: A response of plants to toxic levels of metals such as cadmium, mercury, or aluminum that involves chelation, sequestration, and degradation of metal ions, as well as changes in gene expression and oxidative stress.
UV radiation stress response: A response of plants to exposure to ultraviolet radiation that includes the production of UV-absorbing pigments, repair mechanisms for DNA damage, and changes in gene expression.
Pathogen and herbivore stress response: A response of plants to biotic stresses that involves the activation of defense mechanisms such as the production of phytohormones, secondary metabolites, and pathogenesis-related proteins.
Flooding stress response: A response of plants to waterlogging or submergence that induces changes in gene expression, carbohydrate metabolism, and antioxidant systems, among other adaptive responses.
Light stress response: A response of plants to high or low light intensity or quality that triggers changes in photosynthetic pigment composition, chloroplast structure, and gene expression.
Nutrient deficiency or excess stress response: A response of plants to imbalances in essential nutrients such as nitrogen, phosphorus, or potassium that induces changes in gene expression, uptake, transport, and storage of nutrients.
"Plants can sense being touched..."
"Many plants produce secondary metabolites, known as allelochemicals, that influence the behavior, growth, or survival of herbivores."
"These chemical defenses can act as repellents or toxins to herbivores or reduce plant digestibility."
"Another defensive strategy of plants is changing their attractiveness."
"To prevent overconsumption by large herbivores, plants alter their appearance by changing their size or quality..."
"Other defensive strategies used by plants include escaping or avoiding herbivores at any time in any place..."
"Another approach diverts herbivores toward eating non-essential parts..."
"...enhances the ability of a plant to recover from the damage caused by herbivory."
"Some plants encourage the presence of natural enemies of herbivores, which in turn protect the plant."
"Each type of defense can be either constitutive (always present in the plant) or induced (produced in reaction to damage or stress caused by herbivores)."
"Historically, insects have been the most significant herbivores..."
"...the evolution of land plants is closely associated with the evolution of insects."
"The study of plant defenses against herbivory is important, not only from an evolutionary viewpoint..."
"...but also for the direct impact that these defenses have on agriculture, including human and livestock food sources."
"...as beneficial 'biological control agents' in biological pest control programs..."
"...and in the search for plants of medical importance."
"Many plants produce secondary metabolites..."
"...strategies to defend against damage caused by herbivores."
"...they can use several strategies to defend against damage caused by herbivores."