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Plant defense against herbivory or host-plant resistance is a range of adaptations evolved by plants which improve their survival and reproduction by reducing the impact of herbivores. Many plants produce secondary metabolites , known as allelochemicals , that influence the behavior, growth, or survival of herbivores.
Herbivores are dependent on plants for food, and have coevolved mechanisms to obtain this food despite the evolution of a diverse arsenal of plant defenses against herbivory. Herbivore adaptations to plant defense have been likened to "offensive traits" and consist of those traits that allow for increased feeding and use of a host. [1]
It is one of the general plant defense strategies against herbivores, the other being resistance, which is the ability of plants to prevent damage (Strauss and Agrawal 1999). Plant defense strategies play important roles in the survival of plants as they are fed upon by many different types of herbivores, especially insects, which may impose ...
These differ in that constitutive defenses are present before an herbivore attacks, while induced defenses are activated only when attacks occur. [2] [3] [4] In addition to constitutive defenses, initiation of specific defense responses to herbivory is an important strategy for plant persistence and survival. [1]
The myriad defenses displayed by plants means that their herbivores need a variety of skills to overcome these defenses and obtain food. These allow herbivores to increase their feeding and use of a host plant. Herbivores have three primary strategies for dealing with plant defenses: choice, herbivore modification, and plant modification.
Tritrophic interactions in plant defense against herbivory describe the ecological impacts of three trophic levels on each other: the plant, the herbivore, and its natural enemies. They may also be called multitrophic interactions when further trophic levels , such as soil microbes, endophytes , or hyperparasitoids (higher-order predators) are ...
Studies comparing the relative impacts of mutualistic endophytes on inducible defenses and tolerance show a central function of infection in determining both responses to herbivore damage. [100] On the whole, molecular mechanisms behind endophyte-mediated plant defense has been an increasing focus of research over the past ten years. [101] [102]
Jasmonic acid (JA) is a plant hormone that increases in concentration in response to insect herbivore damage. The rise in JA induces the production of proteins functioning in plant defenses. JA also induces the transcription of multiple genes coding for key enzymes of the major pathways for secondary metabolites.