title: Suppression of Cdc27B expression induces plant defence responses.
abstract: Non-host resistance is the most general form of disease resistance in plants because it is effective against most phytopathogens. The importance of hypersensitive responses (HRs) in non-host resistance of Nicotiana species to the oomycete Phytophthora is clear. INF1 elicitin, an elicitor obtained from the late-blight pathogen Phytophthora infestans, is sufficient to induce a typical HR in Nicotiana species. The molecular mechanisms that underlie the non-host resistance component of plant defence responses have been investigated using differential-display polymerase chain reaction (PCR) in a model HR system between INF1 elicitin and tobacco BY-2 cells. Differential-display PCR has revealed that Cdc27B is down-regulated in tobacco BY-2 cells after treatment with INF1 elicitin. Cdc27B is one of 13 essential components of the anaphase-promoting complex or cyclosome (APC/C)-type E3 ubiquitin ligase complex in yeast. This APC/C-type E3 ubiquitin ligase complex regulates G2-to-M phase transition of the cell cycle by proteolytic degradation. In this study, we investigated the roles of this gene, NbCdc27B, in plant defence responses using virus-induced gene silencing. Suppression of NbCdc27B in Nicotiana benthamiana plants induced defence responses and a gain of resistance to Colletotrichum lagenarium fungus. Elicitin-induced hypersensitive cell death (HCD) was inhibited mildly in plants silenced with tobacco rattle virus::Cdc27B. Cdc27B could manage the signalling pathways of plant defence responses as a negative regulator without HCD.
authors.affiliation: Laboratory of Plant Pathology & Genetic Engineering, Faculty of Agriculture, Okayama University, Okayama 700-8530, Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Kudo
authors.forename: Tomoko
authors.initials: T
authors.lastname: Suzuki
authors.forename: Sumie
authors.initials: S
authors.lastname: Fukuoka
authors.forename: Shuta
authors.initials: S
authors.lastname: Asai
authors.forename: Hiroko
authors.initials: H
authors.lastname: Suenaga
authors.forename: Michiko
authors.initials: M
authors.lastname: Sasabe
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Takano
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Okuno
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Toyoda
authors.forename: Tomonori
authors.initials: T
authors.lastname: Shiraishi
authors.forename: Yuki
authors.initials: Y
authors.lastname: Ichinose
authors.forename: Yoshi-Shige
authors.initials: YS
authors.lastname: Inagaki