O'Donnell Philip J, Schmelz Eric A, Moussatche Patricia, Lund Steven T, Jones Jeffery B, Klee Harry J
Department of Horticultural Sciences, University of Florida, Gainesville, FL 32611, USA.
Plant J. 2003 Jan;33(2):245-57. doi: 10.1046/j.1365-313x.2003.01619.x.
Ethylene and salicylic acid (SA) are key intermediates in a host's response to pathogens. Previously, we have shown using a tomato compatible interaction that ethylene and SA act sequentially and are essential for disease symptom production. Here, we have examined the relationship between the two signals in the Arabidopsis-Xanthomonas campestris pv. campestris (Xcc) compatible interaction. Preventing SA accumulation by expression of the nahG gene reduced subsequent ethylene production and altered the development of disease symptoms, with plants showing no visible chlorosis. The ethylene insensitive lines, etr1-1 and etr2-1, on the other hand, accumulated SA and exhibited normal but precocious symptom development. Therefore, Arabidopsis, like tomato, was found to exhibit co-operative ethylene and SA action for the production of disease symptoms. However, in Arabidopsis, SA was found to act upstream of ethylene. Jasmonic acid and indole-3-acetic acid levels were also found to increase in response to Xcc. In contrast to ethylene, accumulation of these hormones was not found to be dependent on SA action. These results indicate that the plants response to a virulent pathogen is a composite of multiple signaling pathways.
乙烯和水杨酸（SA）是宿主对病原体反应的关键中间产物。此前，我们利用番茄亲和互作实验表明，乙烯和SA依次发挥作用，且对病害症状的产生至关重要。在此，我们研究了拟南芥-野油菜黄单胞菌野油菜致病变种（Xcc）亲和互作中这两种信号之间的关系。通过表达nahG基因来阻止SA积累，会降低随后的乙烯产生，并改变病害症状的发展，植株未出现明显的黄化现象。另一方面，乙烯不敏感型品系etr1-1和etr2-1积累了SA，并表现出正常但早熟的症状发展。因此，发现拟南芥与番茄一样，在病害症状产生方面表现出乙烯和SA的协同作用。然而，在拟南芥中，发现SA在乙烯上游发挥作用。还发现茉莉酸和吲哚-3-乙酸水平也会因Xcc而升高。与乙烯不同，未发现这些激素的积累依赖于SA的作用。这些结果表明，植物对毒性病原体的反应是多种信号通路的综合表现。
