Department of Plant Sciences, University of Tennessee, Knoxville, TN, 37996, USA.
Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA.
New Phytol. 2019 Jan;221(2):946-959. doi: 10.1111/nph.15400. Epub 2018 Aug 23.
Plant-parasitic cyst nematodes successfully exploit various phytohormone signaling pathways to establish a new hormonal equilibrium that facilitates nematode parasitism. Although it is largely accepted that ethylene regulates plant responses to nematode infection, a mechanistic understanding of how ethylene shapes plant-nematode interactions remains largely unknown. In this study, we examined the involvement of various components regulating ethylene perception and signaling in establishing Arabidopsis susceptibility to the cyst nematode Heterodera schachtii using a large set of well-characterized single and higher order mutants. Our analyses revealed the existence of two pathways that separately engage ethylene with salicylic acid (SA) and cytokinin signaling during plant response to nematode infection. One pathway involves the canonical ethylene signaling pathway in which activation of ethylene signaling results in suppression of SA-based immunity. The second pathway involves the ethylene receptor ETR1, which signals independently of SA acid to affect immunity, instead altering cytokinin-mediated regulation of downstream components. Our results reveal important mechanisms through which cyst nematodes exploit components of ethylene perception and signaling to affect the balance of hormonal signaling through ethylene interaction with SA and cytokinin networks. This hormonal interaction overcomes plant defense and provokes a susceptible response.
植物寄生性囊线虫成功地利用各种植物激素信号通路来建立新的激素平衡，从而促进线虫寄生。尽管人们普遍认为乙烯调节植物对线虫感染的反应，但乙烯如何影响植物与线虫相互作用的机制在很大程度上仍不清楚。在这项研究中，我们利用一组经过充分表征的单突变体和更高阶突变体，研究了调节乙烯感知和信号转导的各种成分在建立拟南芥对囊线虫 Heterodera schachtii 的易感性中的作用。我们的分析揭示了在植物对线虫感染的反应过程中，乙烯与水杨酸（SA）和细胞分裂素信号分别参与两条途径的存在。一条途径涉及经典的乙烯信号通路，其中乙烯信号的激活导致基于 SA 的免疫抑制。第二条途径涉及乙烯受体 ETR1，它独立于 SA 酸信号传递来影响免疫，而是改变细胞分裂素介导的下游成分的调节。我们的研究结果揭示了囊线虫利用乙烯感知和信号转导成分的重要机制，通过乙烯与 SA 和细胞分裂素网络的相互作用来影响激素信号的平衡。这种激素相互作用克服了植物防御，引发了易感性反应。
