100 ブラシノステロイドがタバコに誘導する病害抵抗性の解析

概要

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To study the potentialities of brassinosteroid (BR) activity on stress responding systems, we analyzed its ability to induce disease resistance in tobacco. Wild-type tobacco treated with brassinolide (BL), the most active BR, exhibited enhanced resistance to the viral pathogen tobacco mosaic virus (TMV), the bacterial pathogen Pseudomonas syringae pv. tabaci (Pst), and the fungal pathogen Oidium sp. The measurement of salicylic acid (SA) in wild-type plant treated with BL and the pathogen infection assays using NahG transgenic plants indicate that BL-induced resistance does not require SA biosynthesis. BL treatment did not induce either acidic or basic defense gene expression, suggesting that BL-induced resistance is distinct from systemic acquired resistance (SAR) and wound-inducible disease resistance. Analysis using brassinazole, a specific inhibitor for BR biosynthesis and the measurement of BRs in TMV-infected tobacco leaves indicated that steroid hormone-mediated disease resistance (SDR) plays part in defense response in tobacco. Simultaneous activation of SAR and SDR by SAR inducers and BL, respectively, exhibited additive protective effects against TMV and Pst, indicating that there is no cross-talk between SAR signaling and SDR signaling pathway downstream of BL. Our data suggest that SDR functions in the innate immunity system of higher plants.
植物化学調節学会の論文
2002-10-31