McNellis T W, Mudgett M B, Li K, Aoyama T, Horvath D, Chua N H, Staskawicz B J
Department of Plant and Microbial Biology, University of California, Berkeley 94720, USA.
Plant J. 1998 Apr;14(2):247-57. doi: 10.1046/j.1365-313x.1998.00106.x.
Pathogenic strains of Pseudomonas syringae pv. tomato carrying the avrRpt2 avirulence gene specifically induce a hypersensitive cell death response in Arabidopsis plants that contain the complementary RPS2 disease resistance gene. Transient expression of avrRpt2 in Arabidopsis plants having the RPS2 gene has been shown to induce hypersensitive cell death. In order to analyze the effects of conditional expression of avrRpt2 in Arabidopsis plants, transgenic lines were constructed that contained the avrRpt2 gene under the control of a tightly regulated, glucocorticoid-inducible promoter. Dexamethasone-induced expression of avrRpt2 in transgenic lines having the RPS2 gene resulted in a specific hypersensitive cell death response that resembled a Pseudomonas syringae-induced hypersensitive response and also induced the expression of a pathogenesis-related gene (PR1). Interestingly, high level expression of avrRpt2 in a mutant rps2-101C background resulted in plant stress and ultimately cell death, suggesting a possible role for avrRpt2 in Pseudomonas syringae virulence. Transgenic RPS2 and rps2 plants that contain the glucocorticoid-inducible avrRpt2 gene will provide a powerful new tool for the genetic, physiological, biochemical, and molecular dissection of an avirulence gene-specified cell death response in both resistant and susceptible plants.
携带avrRpt2无毒基因的丁香假单胞菌番茄致病变种，能在含有互补抗病基因RPS2的拟南芥植物中特异性诱导超敏细胞死亡反应。已证明，在具有RPS2基因的拟南芥植物中瞬时表达avrRpt2可诱导超敏细胞死亡。为了分析avrRpt2在拟南芥植物中条件表达的影响，构建了转基因株系，这些株系中的avrRpt2基因受严格调控的糖皮质激素诱导型启动子控制。在地塞米松诱导下，具有RPS2基因的转基因株系中avrRpt2的表达导致了一种特异性超敏细胞死亡反应，该反应类似于丁香假单胞菌诱导的超敏反应，还诱导了病程相关基因（PR1）的表达。有趣的是，在突变体rps2 - 101C背景下高水平表达avrRpt2会导致植物胁迫并最终导致细胞死亡，这表明avrRpt2在丁香假单胞菌的毒力中可能发挥作用。含有糖皮质激素诱导型avrRpt2基因的转基因RPS2和rps2植物，将为对抗性和感病植物中无毒基因指定的细胞死亡反应进行遗传、生理、生化和分子剖析提供一个强大的新工具。
