Defense, inducible systems

In the coevolutionary interactions of plants and animals, lipids play a major role. They function as ecomones (pheromones, allomones and kairomones) and have been classified by their function. Host plant resistance is partially dependent on these chemical constituents. Lipids may be subdivided into two types. Volatile lipids are generally involved in long distance interactions whereas non-volatile lipids are generally involved after the insect has contacted the host plant. Several examples of each are reviewed. Utilization of these compounds to promote increased host plant resistance could be accomplished by selection of plants rich in allomones, lacking kairomones for a particular pest or those with inducible systems of defense. Another approach is to isolate the defensive compounds of one plant and apply them to crop plants. Trap crops could also be used to lure insects away from other crops. 

In the plant, part of the metabolic cost of producing and maintaining pools of secondary compounds may be reduced by using compounds which contain only carbon, hydrogen and oxygen (which are rarely limiting), by recycling the compounds or by use of inducible systems of defense. 

Inducible systems of defense (phytoalexins) are widespread in plants and are effective against many types of fungi and bacteria (37,38). Similar systems have been demonstrated in a few cases with insects and are probably common in nature (see for example reference 39). Although Inducible systems of insect resistance would seem to be efficient and effective, no system is foolproof. The larvae of Epilachna tredecimnotata cut a circular trench in Cucurbita leaves and prevent mobilization of the deterrent substances to the area which is then consumed (40). 

The self-concept and its system of defense mechanisms are intricately interwoven. The breakdown of defenses induces depersonalization. Because defenses limit our ability to see ourselves with clarity and objectivity, the therapeutic poten-... 

Kui, J. (1983) Induced Systemic Resistance in Plants to Diseases Caused by Fungi and Bacteria. In The Dynamics of Host Defense (editors J.A. Bailey and B.J. Deveerall), Academic Press, Australia. 191-221. 

Pretreatment of the plants with CTS before pathogen infection will result in better plant protection than CTS treatment after pathogen infection. This is accord with the PRIME mechanism in induced systemic resistance of plants. PRIME mechanism has been put forward during the past several years (Conrath et al. 2006) it has been demonstrated that pretreatment of plants with elicitor of systemic resistance leads to the direct activation of a set of defense reactions and also primes the plants for stronger elicitation when it is affected by disease at a later stage. 

The role of salicyhc acid as a defense response (systemic acquired resistance) inducing signal molecule in plants was reviewed, e.g., by Klessig and Malamy (1994) and Vemooij et al. (1994). 

Contamination of blood products with lymphocytes can lead to transfusion-induced reactions ranging from a mild fever to severe reactions such as alloimmunization and graft versus host disease (GvHD), in which the transfused lymphocytes (graft) survive the defensive immune reaction of the patient (host) and start a reaction which destroys the cells of the host. The patient also may develop an immune response to the human leukocyte antigen (HLA) type of the graft s cells and reject all platelet transfusions that do not match their own HLA system. The HLA system, found on blood platelets and lymphocytes, is more compHcated than, but similar to, the ABO blood group system of red cells. 

A wide diversity of herbal remedies have purported abilities to stimulate defense functions. Complexes of carbohydrate and lignin, which are present in some herbs, modulate enteric immune functions (Kiyohara et al, 2000), and the changes in cytokine secretion (Matsumoto and Yamada, 2000) can trigger systemic responses. The polysaccharides present in other herbal medicines augment production of immunoglobulin (Ig) A by the Peyer s patches in the small intestine (Sakushima et al, 1997 Yu et al, 1998). The responses of the enteric immune system to lectins are variable (Pusztai 1993), and can elicit systemic responses (Lavelle et al, 2000). Other phytochemicals provide protection by inducing detoxification pathways in mucosal cells (Williamson et al, 1998). 

Nonaka, A., Manabe, T., Kyt ku, T., Tamura, K. and Tobe, T. (1990). Changes in lipid peroxide and oxygen radical scavengers in caerulein-induced acute pancreatitis. Imbalance between the offensive and defense systems. Digestion 47, 130-137. 

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