Molecular and physiological mechanism of oxidative burst in relation to signal transduction for defense response of plant to infection

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Plants cause induced defense response to pathogens or elicitor. Rapid activation of superoxide generating reaction (Oxidative burst : OXB) is induced at the beginning of induction of the defense response. This reaction system was shown to be dependent on an NADPH oxidase in plasma membrane regulated by signal trasnduction system involving Ca^<2+>, calumodulin, protein kinase, etc. In the present research, isolation and characterization of the NADPH oxidase, signal transduction stimulated by OXB and OXB-induced induction of defense-related genes were investigated with the following results. 1. Time course increase in potential for response with OXB on the sliced surface during aging after slicing of potato tuber. 2. Induction of sub-systemic OXB at aged sliced surface distant from elicitor treated side with local OXB.3. Kinetics of O_2 generating NADPH oxidase in isolated plasma membrane fraction of potato tuber. 4. Various inhibitor for Ca^<2+> signaling or protein kinase inhibited ind … More uctions of local and sub-systemic. 5. Solubirization of active 0_2 generating NADPH oxidase from plasma membrane by detergents. 6. Detection of several active bands in polyacril amid gel after electrophoresis of solubilized NADPH oxidase. 7. Cloning of cDNA homologous with gp91p^<phox> of human leukocytes and detection of homology with those from rice and Arabidopsis plants. 8. Detection of signal by antibody against p67^<phax> from human leukocytes in the fraction on SDS-PAGE of soluble protein from potato tuber tissues. 9. Inhibition by Ca^<2+> inhibitor of elicitor-stimulated OXB resulted in little induction of defense genes. lO.OXB stimulated phospholypase A_2 depending on a GTP binding protein. 11. OXB-related cytoplasmic aggregation was dependent on actin molecules with actin-binding proteins. 12. OXB did not necessarily associated with induction of enzymes related with phytoalexin production. 13. Further characterization of 0_2 generating NADPH oxidase was necessary for understanding OXB at molecular level of enzyme and gene. Less