| Research Abstract |
Chitin-oligosaccharidesβ-glucan and lipopolysacharides elicitors, which had potential to induce oxidative burst and phytoalexin production in suspension cultured cells of rice plant, were isolated and characterized. Receptors of the elicitors were isolated and characterized. Interaction between elicitor and receptor was followed by activation of phospholypase under regulation by protein kinases in a close relation to activation of active oxygen generation.. Two sets of NADPH oxidase genes were cloned from potato and Nicotiana benthamiana, named StrbohA and StrbohB and NbrbohA and NbrbohB, respectively.
In potato tissues infected with Phyiophthora infestans, Ca^<2+> signaling was immediately stimulated, following activation of oxidative burst system consisted of Strboh A through Ca^<2+> dependent protein kinase in the case of incompatible interaction. A MAP kinase cascade involving StMEK 1 and StMAPI was stimulated in both compatible and incompatible interaction, followed by activation of gene expression of StrbohB for secondary oxidative bust and enzymes for synthesis of sesuquiterpenoid phytoalexin, HMG, PVS etc.. However, activation of these enzymes was stimulated in relation to the first oxidative bust characteristic of incompatible interaction. StMEK1^<DD>, a constantly active form of StMEK1, was found to stimulate the oxidative burst depending on StrbohB, As RSV3, gene of vestipiradien syntase was sensitively response to infection with compatible race, StMEK1^<DD> conjugated with the promotor of PVS3 was subjected to toransformation of potato cultivars. The transformed potato plants expressed tolerance to P infestans, Ahernaria solani, or Erwinia cartovola with an activation of MAP kinase cascade, expression of StrbohB, response of oxidative burst and hypersensitive resistant reaction.
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