Centre for Crop and Disease Management, Curtin University, Bentley, Perth, 6102, Australia.
Bio-Protection Research Centre, School of Fundamental Sciences, Massey University, Palmerston North, 4474, New Zealand.
Sci Rep. 2021 Oct 7;11(1):19958. doi: 10.1038/s41598-021-99415-5.
Forests are under threat from pests, pathogens, and changing climate. A major forest pathogen worldwide is the hemibiotroph Dothistroma septosporum, which causes dothistroma needle blight (DNB) of pines. While D. septosporum uses effector proteins to facilitate host infection, it is currently unclear whether any of these effectors are recognised by immune receptors to activate the host immune system. Such information is needed to identify and select disease resistance against D. septosporum in pines. We predicted and investigated apoplastic D. septosporum candidate effectors (DsCEs) using bioinformatics and plant-based experiments. We discovered DsCEs that trigger cell death in the angiosperm Nicotiana spp., indicative of a hypersensitive defence response and suggesting their recognition by immune receptors in non-host plants. In a first for foliar forest pathogens, we developed a novel protein infiltration method to show that tissue-cultured pine shoots can respond with a cell death response to a DsCE, as well as to a reference cell death-inducing protein. The conservation of responses across plant taxa suggests that knowledge of pathogen-angiosperm interactions may also be relevant to pathogen-gymnosperm interactions. These results contribute to our understanding of forest pathogens and may ultimately provide clues to disease immunity in both commercial and natural forests.
森林受到害虫、病原体和气候变化的威胁。一种全球范围内的主要森林病原体是兼性生物 Dothistroma septosporum，它会引起松树的 Dothistroma 针叶枯病（DNB）。虽然 D. septosporum 使用效应蛋白来促进宿主感染，但目前尚不清楚这些效应蛋白中是否有任何一种被免疫受体识别，从而激活宿主的免疫系统。这种信息对于识别和选择松树对 D. septosporum 的抗病性是必要的。我们使用生物信息学和基于植物的实验来预测和研究细胞外 D. septosporum 候选效应蛋白（DsCEs）。我们发现了 DsCEs，它们在被子植物 Nicotiana spp. 中引发细胞死亡，表明其对非宿主植物中的免疫受体的识别，引发了过敏反应防御。这是叶状森林病原体的首例研究，我们开发了一种新的蛋白质渗透方法，表明组织培养的松树嫩枝可以对 DsCE 以及参考的细胞死亡诱导蛋白产生细胞死亡反应。在植物分类群中，这种反应的保守性表明，对病原体-被子植物相互作用的了解可能也与病原体-裸子植物相互作用有关。这些结果有助于我们了解森林病原体，并最终为商业和自然森林的疾病免疫提供线索。
