Yucel I, Xiao Y X, Hutcheson S W
Department of Botany, University of Maryland, College Park 20742-5815.
Appl Environ Microbiol. 1989 Jul;55(7):1724-9. doi: 10.1128/aem.55.7.1724-1729.1989.
The inhibitor sensitivity and timing of the ionic response of suspension-cultured tobacco cells were used as a bioassay for the Pseudomonas syringae signal that elicits the hypersensitive response in resistant plants. The ionic response of tobacco cell suspensions inoculated with P. syringae pv. syringae 61 and P. syringae pv. pisi grown in rich media was inhibited by rifampin, tetracycline, and streptomycin during a 2- to 2.5-h induction stage. Coculturing the bacteria with tobacco cells for 3 h or more before inoculating fresh tobacco cells specifically abolished the sensitivity of the ionic response to these inhibitors and reduced the response time of the tobacco cells from 3 to 1 h. The apparent activation of the bacteria during coculture was not dependent on the plant cells and could be achieved by incubating the bacteria in a nitrogen-deficient medium containing a metabolizable carbon source. Addition of proteose peptone and Casamino Acids to this medium suppressed activation of the bacteria. The results suggest that the hypersensitive response-eliciting signal forms late in the induction stage, perhaps as a result of the derepression of some of the P. syringae genes functional in elicitation of the hypersensitive response. The nature of the activated state remains elusive but is consistent with the accumulation of protein(s) whose activity indirectly elicits the ionic response.
悬浮培养的烟草细胞的抑制剂敏感性和离子反应时间被用作一种生物测定方法，以检测丁香假单胞菌的信号，该信号可在抗性植物中引发过敏反应。在富含培养基中生长的丁香假单胞菌丁香致病变种61和豌豆致病变种接种烟草细胞悬浮液后的离子反应，在2至2.5小时的诱导阶段受到利福平、四环素和链霉素的抑制。在接种新鲜烟草细胞之前，将细菌与烟草细胞共培养3小时或更长时间，可特异性消除离子反应对这些抑制剂的敏感性，并将烟草细胞的反应时间从3小时缩短至1小时。共培养期间细菌的明显活化不依赖于植物细胞，可通过将细菌在含有可代谢碳源的缺氮培养基中孵育来实现。向该培养基中添加蛋白胨和酪蛋白氨基酸可抑制细菌的活化。结果表明，引发过敏反应的信号在诱导阶段后期形成，可能是由于丁香假单胞菌中一些在引发过敏反应中起作用的基因去阻遏的结果。活化状态的性质仍然难以捉摸，但与间接引发离子反应的蛋白质积累一致。
