Plant injury chemical responses

Chemical factors are also involved in the resistance of plants to disease and in the competitive ability of a plant to survive within a community of plants. Plant stress may also generate a chemical response giving rise to compounds known as the phytoalexins, the nature of which will depend on the chemistry of the host plant (18, 19). Such response to injury or infection is of great Interest because it has stimulated investigations of the nature of the bloregulatory processes involved. 

Chemical responses to plant injury and plant aging GERHARD SPITELLER... 

Consider the chemical plant example. While the hazard could be defined as death or injury of residents around the plant (the loss event), there may be many factors involved in such a loss that are beyond the control of the plant designers and operators. One example is the atmospheric conditions at the time of the release, such as velocity and direction of the wind. Other factors in a potential accident or loss are the location of humans around the plant and community emergency preparedness, both of which may be under the control of the local or state government. The designers of the chemical plant have a responsibility to provide the information necessary for the design and operation of appropriate emergenq preparedness equipment and procedures, but their primary design responsibility is the part of a potential... 

Immunization of cucumbers by (L lagenarium, C. cucumerinum, P. 1achrymans or TNV generates a systemic increase in peroxidase activities (. TJ, ] 9, 8U) > Like 1 i gni f ic a t ion and phytoalexin induction, peroxidase activities also rise more quickly in response to infection in leaves of immunized plants, even though total activity eventually may be highest in infected susceptible leaves (77). Several other stimuli can induce local (mechanical and chemical injury) or systemic (senescence, ethylene) peroxidase increases that are not accompanied by increased disease resistance. Thus, enhanced peroxidase activity per se may not be a defense mechanism, but may be a necessary adjunct with appropriate chemical substrates for processes important in disease resistance, e.g., lignification, suberization, and me 1anization. 

Paraffin followed by candelilla wax and microcrystalline waxes, and eventually by beeswax, are considered as the most effective moisture barriers derived from edible waxes (Morillon et al. 2002). There is no satisfactory chemical definition for the term wax which is used for a variety of products of mineral, botanical and animal origin that contain various kinds of fatty materials (Table 23.4). The term resins or lacs can also be used for plant or insect secretions that take place along resins ducts, often in response to injury or infection, and result in more acidic substances (Hernandez 1994). However, all waxes tend to contain wax esters as major components, that is, esters of long-chain fatty alcohols with long chain fatty acids. Depending on their source, they may additionally include hydrocarbons, sterol esters, aliphatic aldehydes, primary and secondary alcohols, diols, ketones, triacylglycerols, and so on. 

Phosgene-based synthesis of carbamate pesticides may pass through the intermediate methyl isocyanate, which was responsible for the catastrophe at the Union Carbide chemical plant in Bhopal, India, in 1984. A relief valve lifted on a storage tank containing methyl isocyanate, releasing a cloud of toxic gas onto residential areas surrounding the plant, ultimately causing the death of more than 15,000 people, and the injury of several hundred thousand more. ... 

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