Anthropogenic emissions have caused atmospheric carbon dioxide (CO2) concentrations to double since the industrial revolution. Although this could benefit plant growth from the ‘CO2 fertilisation’ effect, recent studies report conflicting impacts of elevated CO2 (eCO2) on plant–pathogen interactions. Fungal pathogens are the leading cause of plant disease. Since climate change has been shown to affect the distribution and virulence of these pathogens, it is important to understand how their plant hosts may also respond. This review assesses existing reports of positive, negative, and neutral effects of eCO2 on plant immune responses to fungal pathogen infection. The interaction between eCO2 and immunity appears specific to individual pathosystems, dependent on environmental context and driven by the interactions between plant defence mechanisms, suggesting no universal effect can be predicted for the future. This research is vital for assessing how plants may become more at risk under climate change and could help to guide biotechnological efforts to enhance resistance in vulnerable species. Despite the importance of understanding the effects of eCO2 on plant immunity for protecting global food security, biodiversity, and forests in a changing climate, many plant–pathogen interactions are yet to be investigated. In addition, further research into the effects of eCO2 in combination with other environmental factors associated with climate change is needed. In this review, we highlight the risks of eCO2 to plants and point to the research required to address current unknowns.

中文翻译：

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大气二氧化碳浓度升高和植物对真菌病原体的免疫力：风险大于收益吗？

自工业革命以来，人为排放导致大气中二氧化碳 (CO2) 浓度增加了一倍。虽然“二氧化碳施肥”效应可能有利于植物生长，但最近的研究报告指出，二氧化碳 (eCO2) 升高对植物与病原体相互作用的影响是相互矛盾的。真菌病原体是植物病害的主要原因。由于气候变化已被证明会影响这些病原体的分布和毒力，因此了解它们的植物宿主也可能如何反应非常重要。本综述评估了 eCO2 对真菌病原体感染的植物免疫反应的积极、消极和中性影响的现有报告。eCO2 和免疫之间的相互作用似乎特定于个体病理系统，依赖于环境背景并由植物防御机制之间的相互作用驱动，这表明无法预测未来的普遍影响。这项研究对于评估植物在气候变化下如何变得更加危险至关重要，并有助于指导生物技术努力增强脆弱物种的抵抗力。尽管了解 eCO2 对植物免疫力的影响对于保护全球粮食安全、生物多样性和气候变化中的森林非常重要，但许多植物与病原体的相互作用仍有待研究。此外，还需要进一步研究 eCO2 与与气候变化相关的其他环境因素相结合的影响。在这篇综述中，我们强调了 eCO2 对植物的风险，并指出了解决当前未知问题所需的研究。