Department of Agronomy, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
Plant Protection Department, Slovenian Institute of Hop Research and Brewing, Žalec, Slovenia.
Plant Cell Rep. 2017 Oct;36(10):1599-1613. doi: 10.1007/s00299-017-2177-1. Epub 2017 Jul 11.
Dynamic transcriptome profiling revealed excessive, yet ineffective, immune response to V. nonalfalfae infection in susceptible hop, global gene downregulation in shoots of resistant hop and only a few infection-associated genes in roots. Hop (Humulus lupulus L.) production is hampered by Verticillium wilt, a disease predominantly caused by the soil-borne fungus Verticillium nonalfalfae. Only a few hop cultivars exhibit resistance towards it and mechanisms of this resistance have not been discovered. In this study, we compared global transcriptional responses in roots and shoots of resistant and susceptible hop plants infected by a lethal strain of V. nonalfalfae. Time-series differential gene expression profiles between infected and mock inoculated plants were determined and subjected to network-based analysis of functional enrichment. In the resistant hop cultivar, a remarkably low number of genes were differentially expressed in roots in response to V. nonalfalfae infection, while the majority of differentially expressed genes were down-regulated in shoots. The most significantly affected genes were related to cutin biosynthesis, cell wall biogenesis, lateral root development and terpenoid biosynthesis. On the other hand, susceptible hop exhibited a strong defence response in shoots and roots, including increased expression of genes associated with plant responses, such as innate immunity, wounding, jasmonic acid pathway and chitinase activity. Strong induction of defence-associated genes in susceptible hop and a low number of infection-responsive genes in the roots of resistant hop are consistent with previous findings, confirming the pattern of excessive response of the susceptible cultivar, which ultimately fails to protect the plant from V. nonalfalfae. This research offers a multifaceted overview of transcriptional responses of susceptible and resistant hop cultivars to V. nonalfalfae infection and represents a valuable resource in the study of this plant-pathogen interaction.
动态转录组谱分析显示，易感啤酒花对 V. nonalfalfae 感染的免疫反应过度，但无效，而抗性啤酒花的地上部基因下调，根部仅有少数与感染相关的基因。啤酒花（Humulus lupulus L.）的生产受到黄萎病的阻碍，该病主要由土壤传播的真菌 V. nonalfalfae 引起。只有少数啤酒花品种对其具有抗性，但其抗性机制尚未发现。在这项研究中，我们比较了受致死菌株 V. nonalfalfae 感染的抗性和易感啤酒花植物的根和地上部的全局转录响应。确定了感染和模拟接种植物之间的时间序列差异基因表达谱，并对其进行了基于网络的功能富集分析。在抗性啤酒花品种中，根中响应 V. nonalfalfae 感染的差异表达基因数量显著较少，而地上部的大多数差异表达基因下调。受影响最显著的基因与角质生物合成、细胞壁生物合成、侧根发育和萜类生物合成有关。另一方面，易感啤酒花在地上部和根部表现出强烈的防御反应，包括与植物反应相关的基因表达增加，如先天免疫、创伤、茉莉酸途径和几丁质酶活性。易感啤酒花中防御相关基因的强烈诱导和抗性啤酒花根部感染响应基因的数量较少与之前的研究结果一致，证实了易感品种过度反应的模式，最终无法保护植物免受 V. nonalfalfae 的侵害。这项研究提供了对 V. nonalfalfae 感染的易感和抗性啤酒花品种的转录响应的多方面概述，是研究这种植物-病原体相互作用的宝贵资源。
