Gus-Mayer S, Naton B, Hahlbrock K, Schmelzer E
Max-Planck-Institut für Züchtungsforschung, Carl-von-Linné-Weg 10, D-50829 Cologne, Germany.
Proc Natl Acad Sci U S A. 1998 Jul 7;95(14):8398-403. doi: 10.1073/pnas.95.14.8398.
Cell suspension cultures of parsley (Petroselinum crispum) have previously been used as a suitable system for studies of the nonhost resistance response to Phytophthora sojae. In this study, we replaced the penetrating fungus by local mechanical stimulation by using a needle of the same diameter as a fungal hypha, by local application of a structurally defined fungus-derived elicitor, or by a combination of the two stimuli. Similar to the fungal infection hypha, the local mechanical stimulus alone induced the translocation of cytoplasm and nucleus to the site of stimulation, the generation of intracellular reactive oxygen intermediates (ROI), and the expression of some, but not all, elicitor-responsive genes. When the elicitor was applied locally to the cell surface without mechanical stimulation, intracellular ROI also accumulated rapidly, but morphological changes were not detected. A combination of the mechanical stimulus with simultaneous application of low doses of elicitor closely simulated early reactions to fungal infection, including cytoplasmic aggregation, nuclear migration, and ROI accumulation. By contrast, cytoplasmic rearrangements were impaired at high elicitor concentrations. Neither papilla formation nor hypersensitive cell death occurred under the conditions tested. These results suggest that mechanical stimulation by the invading fungus is responsible for the observed intracellular rearrangements and may trigger some of the previously demonstrated changes in the activity of elicitor-responsive genes, whereas chemical stimulation is required for additional biochemical processes. As yet unidentified signals may be involved in papilla formation and hypersensitive cell death.
此前，香菜（皱叶欧芹）的细胞悬浮培养物已被用作研究对大豆疫霉非寄主抗性反应的合适系统。在本研究中，我们通过使用与真菌菌丝直径相同的针进行局部机械刺激、局部应用结构明确的真菌衍生激发子或两者结合的方式，替代了穿透性真菌。与真菌感染菌丝类似，单独的局部机械刺激诱导细胞质和细胞核向刺激部位转移、细胞内活性氧中间体（ROI）的产生以及一些（但不是全部）激发子响应基因的表达。当在没有机械刺激的情况下将激发子局部应用于细胞表面时，细胞内ROI也会迅速积累，但未检测到形态变化。机械刺激与同时应用低剂量激发子的组合紧密模拟了对真菌感染的早期反应，包括细胞质聚集、核迁移和ROI积累。相比之下，在高激发子浓度下细胞质重排受到损害。在所测试的条件下，既未发生乳突形成也未发生过敏细胞死亡。这些结果表明，入侵真菌的机械刺激是观察到的细胞内重排的原因，并且可能触发一些先前证明的激发子响应基因活性的变化，而额外的生化过程则需要化学刺激。乳头形成和过敏细胞死亡可能涉及尚未确定的信号。
