Towards an understanding of the impact of drought and elevated CO₂ on the plant-vector-virus interactions of grapevine leafroll disease

在气候变化时期，自然和农业生态系统中的植物健康受到与气候变化相关的非生物胁迫以及害虫和病原体的生物胁迫的影响。本项目旨在评估与气候变化相关的非生物胁迫因素，如CO-₂浓度升高和干旱胁迫对葡萄植物、葡萄卷叶病毒及其病媒--无花果粉虱之间相互作用的影响。GLRaV，特别是GLRaV-3型，改变了植物的CO₂同化，水分利用效率，以及初级和次生代谢产物，最终导致减产，推迟果实成熟，降低葡萄品质。该病毒通过使用受感染的繁殖材料和吸食韧皮部的昆虫媒介(如粉虱)传播。CO、₂升高和水分胁迫会对植物生理和害虫产生重大影响。另一方面，植物病毒对植物造成生物胁迫并改变媒介行为，但它们也像生态系统中的任何其他成员一样暴露在与气候变化相关的非生物应激源中。关于气候变化对葡萄上病毒感染的影响的研究很少，也没有关于粉虱作为病毒载体的研究。从其他病理系统中得出结论是困难的，因为非生物气候变化相关压力的影响通常是物种特有的。到目前为止，研究主要是关于单一气候变化参数与植物、昆虫或病原体的成对相互作用。现在，需要更广泛的研究方法来了解多种应激源之间的相互作用，以及植物、病原体和病媒之间的复杂关系。通过这种方式，研究可以促进制定有效的管理和适应战略，这些战略是在面对气候变化时保持植物健康和生产力所需的。该项目提出了一系列实验，将葡萄暴露在两个气候变化参数(水分胁迫+CO₂)和来自GLRaV-3感染的生物胁迫下。从经典的传播实验开始，我将评估不同气候条件下葡萄的敏感性、传染性和病毒滴度。下一步将评估这些机制(基因表达)及其对植物(氨基酸、酚、C/N、糖、叶绿素)的影响。此外，还研究了GLRav、水分胁迫和ECO₂对粉虱的食物偏好和适合性的影响。几十年来，人们一直在呼吁进行多因素压力实验。这些实验既雄心勃勃又复杂，但它们是洞察卷叶病未来进化的必要的下一步。

In times of climate change, plant health in natural and agricultural ecosystems is affected by abiotic climate change-related stressors in combination with the biotic stress of pests and pathogens. This project aims to evaluate the effects of abiotic climate change-related stressors, such as elevated CO₂ and drought stress, on the interaction between grapevine plants, Grapevine leafroll-associated virus (GLRaV), and its vector, the mealybug Planoccus ficus. GLRaV, specifically the type GLRaV-3, alters the plant's CO₂ assimilation, water use efficiency, and primary and secondary metabolites which eventually leads to reduced yield, delayed fruit maturity, and poor grape quality. The virus spreads through the use of infected propagation material and phloem-sucking insect vectors, such as mealybugs. Elevated CO₂ and water stress can have a significant impact on plant physiology and insect pests. On the other hand, plant viruses cause biotic stress to plants and alter vector behavior, but they are also exposed to the same climate-change-related abiotic stressors as any other member of the ecosystem. There are very few studies on climate change impacts on viral infections in grapevine, and none on mealybugs as virus vectors. Deriving conclusions from other pathosystems is difficult since the effects of abiotic climate-change-related stress usually are species-specific. So far, research has experimented mostly on pairwise interactions of single climate change parameters with plants, insects, or pathogens. Now, broader research approaches are needed to understand the interactions among multiple stressors and the complex relationships among plants, pathogens, and vectors. In this way, research can facilitate the development of effective management and adaptation strategies that are needed to maintain plant health and productivity in the face of climate change. The project proposes a series of experiments exposing grapevines to two climate change parameters (water stress + CO₂) in combination with biotic stress from GLRaV-3 infection. Starting with classic transmission experiments, I will evaluate the susceptibility, infectiousness, and virus titers of grapevines under different climatic conditions. The next step will assess the mechanisms (gene expression) and the effects on plants (amino acids, phenols, C/N, sugars, Chlorophyll). In addition, the influence of GLRaV, water stress, and eCO₂ on the food preference and fitness of mealybugs is also investigated. The call for multifactorial stress experiments has been made for decades. These experiments are ambitious and complex, but they are the necessary next step to gain insight into the evolution of leafroll disease in the future.