Plant-insect interactions natural activators

Walling, 2000), less is known about plant responses to sucking or piercing insects (Du et al, 1998 Williams HI et al, 2005) (see Section on Regulation of Plant Toxicants by Natural Activators ). A recent study of the interactions between different types of herbivorous insects and plant defence volatiles showed that tobacco, Nicotiana tabacum, releases terpenoids and nicotine after caterpillar regurgitate treatment. Colonisation by western flower thrips, Frankliniella occidentalis, was reduced on the regurgitate treated plants, possibly due to the production of nicotine (Delphia et al, 2007). 

The functions of phenylpropanoid derivatives are as diverse as their structural variations. Phenylpropanoids serve as phytoalexins, UV protectants, insect repellents, flower pigments, and signal molecules for plant-microbe interactions. They also function as polymeric constituents of support and surface structures such as lignins and suberins [1]. Therefore, biosynthesis of phenylpropanoids has received much interest in relation to these functions. In addition, the biosynthesis of these compounds has been intensively studied because they are often chiral, and naturally occurring samples of these compounds are usually optically active. Elucidation of these enantioselective mechanisms may contribute to the development of novel biomimetic systems for enantioselective organic synthesis. 

Figure 8. A proposed model for the molecular interaction of the plant cells with a pathogen or an insect in nature, and artificial activation of plant cells with crab shell chitosan to enhance the plant production. See the text for details. 

Winz RA, Baldwin IT (2001) Molecular interactions between the specialist herbivore Manduca sexta (Lepidoptera, Sphingidae) and its natural host Nicotiana attenuata. IV. Insect-induced ethylene reduces jasmonate-induced nicotine accumulation by regulating putrescine V-methyltransferase transcripts. Plant Physiol 125 2189-2202 Woeste KE, Kieber JJ (2000) A strong loss-of-fimction mutation in RANI results in constitutive activation of the ethylene response pathway as well as a Rosette-Lethal phenotype. Plant Cell 12 443-455... 

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