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Plant Defense Systems > Research Links
Being physically fixed in one location, plants have developed quite sophisticated defense mechanisms. In Chapter 37, you learned about how some of the strategies of defense plants have evolved, such as barriers to entry (plant wall, spines, thorns, and prickles) and plant poisons. The following sites discuss various plant defense systems.
37.1 Barriers to Entry
Gene Silencing
Plants have developed elaborate systems of defense to prevent attack by foreign "invaders" such as viruses and fungus. This article from Nature discusses how a plant virus can alter the normal expression of genes in the plant, leading to the altering of the plant's normal morphological and physiological defenses against such invaders.
Keywords: plant virus, gene silencing, plant defense systems
Ant Defenders
One amazing way in which plants have developed a defense mechanism against herbivores centers on the evolution of a symbiotic relationship with an insect or animal species that protects it. This site describes how acacias in Africa have developed a mutualistic relationship with ants for the defense of the plant.
Keywords: plant defense, insects, symbiosis
37.2 Plant Poisons
Poisonous Plants
One of the major ways in which plants defend themselves is through the use of plant poisons. This site lists many plants that are toxic, what part of the plant contains the toxicant and what the symptoms are.
Keywords: poisons, plant defense, toxins
Phytoalexin Toxicants
This site, from the University of Hamburg, provides a detailed description of research performed on toxicants, phytoalexins, and the hypersensitivity response. The researchers studied the interaction of plants and fungal tissue in order to develop a model of plant chemical defense and the methods an attacking fungus may attempt to use to counter these defenses.
Keywords: toxicants, phytoalexins, hypersensitivity response, fungi, plant defense
Adaptation to Plant Toxicity
Unfortunately for plants, some animals have adapted mechanisms that enable them to eat plants that are toxic to other animals. This site describes some of the mechanisms various animals use as an adaptation to eating poisonous plants.
Keywords: adaptation, cyanide, iron
37.3 The Cost of Defense
Plant Defense and Reproductive Energy Budgets
In order to produce toxins, weapons, and barriers against disease and herbivory, plants must expend energy that might otherwise be put toward growth, metabolism, and reproduction. This somewhat dated article describes how the energy budget of reproduction must be balanced by the benefits gained by shunting energy into the development of plant defenses.
Keywords: plant defense, energy budget, plant reproduction
37.4 Responding to Pathogens
Sorghum Anthracnose
Sorghum, a plant in the grass family that resembles sugar cane and maize, is a major food source, especially in Africa. Sorghum Anthracnose, a disease that afflicts this crop, can seriously reduce the productivity of agricultural production of sorghum. This site describes the disease, its mechanism, and how the plant naturally counters the infecting fungus that causes the disease.
Keywords: sorghum, hypersensitivity response, auxins
37.5 Responding to Herbivores
Plant-Produced Pesticides
This article describes some of the toxic chemicals that plants can actively produce to fight off herbivory. While many plants naturally produce toxic chemicals, some can actively produce toxins as a stress response to herbivory, and some can even induce neighboring plants to increase their rates of toxin production through chemical messaging.
Keywords: plant defense, plant pesticide, toxins
Plant-Attracted Herbivore Parasitoids
This 1996 article describes the chemical interactions between plants, herbivores, and parasites of the plant herbivores. The recruitment of herbivore enemies by plants under attack is a terrific example of the amazing adaptability the plants have evolved for their protection.
Keywords: parasitoid, plant defense, herbivores
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