Induction of a sub-systemic oxidative burst by elicitor-stimulated local oxidative burst in potato plant tissues: a possible systemic signalling in systemic acquired resistance

摘要

A hyphal wall component (HWC) elicitor derived from Phytophthora infestans has been known to cause a local induction of oxidative burst (OXB) as well as systemic OXB and systemic acquired resistance (SAR) in potato plants. The systemic induction ofOXB was investigated using potato tuber slices and excised compound leaves. The elicitor-induced local OXB which was monitored as luminol-mediated chemiluminescence (CL), initially appeared as scattered small spots of CL and then further developed CL spots on the whole elicitor-treated surface of slices. The induction treatment of the local OXB on one surface of thick slices caused an OXB on the other surface (sub-systemic OXB). Treatment with elicitor in the presence of an inhibitor O-2 generating NADPH oxidase, diphenyleneiodonium, inhibited appearance of both local and sub-systemic appearance of CL. Systemic CL was not observed in the presence of the inhibitor. A point treatment with HWC-elicitor in the center of horizontally sliced tuber slices induced OXB radially on the whole surface of the slice. The point treatment at the basal and lateral part of vertically sliced tuber slices caused a radial development of CL from the site near the treated point. Local treatment of leaflets of an excised compound leaf with elicitor induced the local OXB as well as the sub-systemic OXB on the other non-treated leaflets. These observations indicated that elicitor treatment may cause not only local but also sub-systemic OXB in tissues of potato plants, suggesting that the local OXB may provide a mobile signal for induction of a systemic OXB responsible for induction of SAR.