Poster: Plant Pathogen/Symbiont Interactions

Abs # 711: Elicitor-stimulated local oxidative burst (OXB) activates a long-distant signaling system involving a cell-to-cell Ca²⁺influx depending on H⁺-ATPase that triggers systemic OXB and systemic acquired resistance (SAR)

Presenter:	Doke, Noriyuki , ndoke@agr.nagoya-u.ac.jp
Authors	Doke, Noriyuki  (A)   Yamasita, Masao  (A)   Sunazaki, Kohji  (A)   Yoshioka, Hirohumi  (A)   Kawakita, Kazuhito  (A)   Park, Hae-June  (A)
Affiliations:	(A): Graduate School of Bioagricultural Sciences, Nagoya University

We had reported that elicitors-induced local OXB depending on activation of an O₂^- generating NADPH oxidase consisted of gp91phox homologue (rboh) in plasma membrane was responsible for induction of SAR in potato and tobacco plants to virulent pathogens. Wild and NahG Nicotiana benthamiana tobacco responded with local OXB to an elicitor, INF1 and showed early systemic induction of defense-related genes (Ntrboh and NbPAL), but the later failed induction of SAR. Elicitor-treatment of leaves showing Agrobacterium-mediated RNA silencing of Ntrboh failed to induce local OXB, resulting in less induction of SAR. Elicitor treatment of a potato tuber slice induced the local OXB in the tissue potentiated by wounding, followed by systemic OXB at distant potentiated tissues through a systemic signal transduction in non-potentiated tissue. Application of extra-cellular Ca²⁺ chelator, Ca²⁺-channel blockers or inhibitors of H⁺-ATPase on the way of systemic signaling stopped the further transduction of the signal. Influx of Ca²⁺ and H⁺ and efflux of K⁺ were found using ion-specific fluorescence probes to concomitantly occur on the way of systemic signaling. In conclusion, OXB and generated H₂O₂ may activate a novel systemic signaling system involving a chain reaction of Ca²⁺ influx depending on H⁺-ATPase from cell-to-cell, leading to the systemic activation of OXB and SAR at distant potentiated tissues.