Signals induced defenses

Small molecule carboxylates are an important class of compounds that plants produce to attract pollinators,44 defend against herbivory,45 7 regulate the cell cycle,48,49 and induce defense responses.50 5 Often these compounds are esterified and volatilized. Plants utilize the emission of volatile esters as chemoattractants and signaling molecules. Classes of volatile compounds include the salicylates and jasmonates, which are ubiquitously distributed in the plant kingdom. Jasmonic acid, salicylic acid, and their methyl ester derivatives, are intimately involved in cell regulation and help control such developmental processes as seed germination, flower development, fruit development, and senescence.14,17,53... 

It is generally believed that there are costs associated with maintaining spines and other inducible defenses, and in fact some known costs for zooplankton that are spiny include reduced growth and reproduction rates, and increased energetic costs of swimming. Many of the compounds responsible for the signal that induces shape changes in plankton have not yet been isolated. 

If SA does not act through H2O2 to induce defense gene expression and resistance, then what is the significance of SA s ability to inhibit catalase and ascorbate peroxidase, and how is the SA signal perceived and transmitted One possible mechanism is that SA-mediated inhibition of catalase and ascorbate peroxidase generates SA free radicals [112], Phenolic free radicals are potent initiators of protein oxidation and lipid peroxidation... 

Though much work has been done to elucidate the mechanism of CTS-induced plant defense, there is still some uncertainty regarding the mechanism. From existing publications, we only know some elements and steps of this signal network, but cannot draw an integrated map of it. Many questions such as the identification of chitosan receptor stiU rmiain unanswered, and further research on the mechanisms of CTS-induced defense is needed. 

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