Schulte R, Bonas U
Institut für Genbiologische Forschung Berlin GmbH, Germany.
J Bacteriol. 1992 Feb;174(3):815-23. doi: 10.1128/jb.174.3.815-823.1992.
The hrp gene cluster from Xanthomonas campestris pv. vesicatoria determines functions necessary not only for pathogenicity on the host plants pepper and tomato but also for the elicitation of the hypersensitive reaction on resistant host and nonhost plants. Transcriptional orientation and expression of the hrp loci were determined with hrp::Tn3-gus fusions. In addition, expression of the hrp loci was studied by RNA hybridization experiments. Expression of the hrp genes was not detectable after growth of the bacteria in complex medium or in minimal medium. However, high levels of induction of hrp gene expression were measured during growth of the bacteria in the plant. To search for a plant molecule responsible for this induction, we examined a variety of materials of plant origin for their ability to induce hrp gene expression. Filtrates from plant suspension cultures induced hrp genes to levels comparable to those induced in the plant. The inducing molecule(s) was found to be heat stable and hydrophilic and to have a molecular mass of less than 1,000 daltons.
来自野油菜黄单胞菌辣椒斑点致病变种的hrp基因簇不仅决定了在寄主植物辣椒和番茄上致病所需的功能，还决定了在抗性寄主和非寄主植物上引发过敏反应所需的功能。通过hrp::Tn3 - gus融合来确定hrp基因座的转录方向和表达情况。此外，还通过RNA杂交实验研究了hrp基因座的表达。在复杂培养基或基本培养基中培养细菌后，未检测到hrp基因的表达。然而，在植物中培养细菌期间，检测到hrp基因表达的高水平诱导。为了寻找负责这种诱导的植物分子，我们检查了多种植物来源的材料诱导hrp基因表达的能力。来自植物悬浮培养物的滤液将hrp基因诱导到与在植物中诱导的水平相当的程度。发现诱导分子是热稳定的且亲水的，分子量小于1000道尔顿。
