[AGRIFOOD] Trophic cascades in a changing climate - effects of elevated CO2 on breakdown of plant defences

[农业食品] 气候变化中的营养级联 - 二氧化碳浓度升高对植物防御崩溃的影响

• 批准号: NE/H018247/1
• 负责人: Thomas Jones
• 金额: $ 8.8万
• 依托单位: CARDIFF UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Training Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FH018247%2F1
• 关键词: AGRIFOOD; Trophic; cascades; changing; climate

Atmospheric carbon dioxide concentrations are predicted to rise to 550ppm by 2050 with concomitant increases in plant productivity. Such predictions seldom account for plant-insect interactions that under climate change may undermine projected increases in primary production by altering plant resistance to herbivory. This has potentially major implications for future food security. Climate change has the potential to modulate plant resistance to herbivory. Elevated CO2 concentrations (eCO2) have been shown to compromise both direct and indirect plant defences to insect herbivores, for example, by down regulation of plant resistance genes leading to enhanced herbivore performance. In many agro-ecosystems, plant defences arise through selective breeding which means plants are unable to adapt resistance mechanisms quickly enough to counteract the compromising effects of eCO2. Moreover, it remains unclear how higher trophic levels will respond to increases in herbivore abundance when plant defences are compromised. Using a multi-trophic system comprising red raspberry (Rubus idaeus), the large raspberry aphid (Amphorophora idaei), a predatory ladybird (Coccinella septempunctata) and an aphid parasitoid (Aphidus ervi), this PhD will investigate the effects of eCO2 on multi-trophic interactions, and specifically plant defence breakdown. Amphorophora idaei is the most significant pest (virus vector) of raspberry production in Europe. Plant resistance to aphid feeding in raspberry cultivars is underpinned by A1 and A10 genes, with A10 conferring stronger resistance, probably through altered leaf wax composition. Preliminary findings suggest aphids overcome resistance in raspberry under eCO2 because of altered gene expression. This project aims to: (1) characterise the effects of eCO2 on plant resistance to different aphid biotypes and identify which genes are implicated; (2) measure the phenotypic changes in plant defence mechanisms underpinning resistance breakdown; and (3) determine how population dynamics of higher trophic levels are affected by climate-induced changes in herbivore abundance. With experimental microcosms in controlled environment facilities, this project will test whether: Hypothesis 1: eCO2 accelerates resistance breakdown, with partially adapted aphid biotypes responding most rapidly to the down-regulation of resistance genes; Hypothesis 2: eCO2 alters composition of leaf waxes associated with aphid resistance; and Hypothesis 3: predator and parasitoid populations will follow a time-lagged increase corresponding to larger aphid populations under eCO2, but mutual interference will impede foraging behaviour at highest aphid densities. This PhD proposal is strongly aligned to the NERC Open Case Priority area of Agrifood research, with particular emphasis on the effects of climate change on proliferation of pests through resistance breakdown in a model crop. The impact of this study will be to provide mechanistic evidence of how multi-trophic interactions are likely to alter under climate change. This will enable crop breeders to target particular plant resistance traits and biocontrol measures for the adaptation and 'future proofing' of crop production under climate change. This contributes directly to the NERC Strategic Plan to enable society to respond urgently to global climate change. The project will meet key objectives of LWEC by investigating how climate change will affect crop-herbivore-enemy interactions and provide timely evidence-based recommendations to policy makers charged with climate change adaptation and mitigation.

预计到2050年，大气中的二氧化碳浓度将上升到550ppm，同时植物生产力也会随之提高。这种预测很少考虑到植物-昆虫的相互作用，在气候变化下，这种相互作用可能会改变植物对草食动物的抗性，从而破坏初级生产的预期增长。这可能对未来的粮食安全产生重大影响。气候变化有可能调节植物对食草动物的抗性。已证明，CO2浓度升高（eCO2）会损害植物对食草昆虫的直接和间接防御，例如，通过下调植物抗性基因，从而增强食草动物的表现。在许多农业生态系统中，植物防御是通过选择性育种产生的，这意味着植物无法足够快地适应抗性机制，以抵消eCO2的危害影响。此外，目前还不清楚当植物防御受到损害时，更高的营养水平将如何应对食草动物丰度的增加。使用一个多营养系统，包括红树莓（Rubus idaeus），大乌藨子蚜虫（Amphorophora idaei），捕食性瓢虫（Coccinella septempunctata）和蚜虫寄生虫（Aphidus ervi），这个博士将研究eCO2对多营养相互作用的影响，特别是植物防御崩溃。idaei是欧洲树莓生产中最重要的害虫（病毒载体）。树莓品种对蚜虫取食的植物抗性是由A1和A10基因支撑的，A10赋予更强的抗性，可能是通过改变叶蜡组成。初步研究结果表明，蚜虫克服抗性树莓eCO2下，因为改变了基因表达。本项目旨在：（1）确定eCO2对植物对不同蚜虫生物型的抗性的影响，并确定哪些基因与之有关;（2）测量植物防御机制中支撑抗性崩溃的表型变化;（3）确定气候诱导的草食动物丰度变化如何影响较高营养级的种群动态。该项目将在受控环境设施中利用实验性微观世界来检验：假设1：二氧化碳排放量增加是否加速了抗性的崩溃，部分适应的蚜虫生物型对抗性基因的下调反应最快;假设2：二氧化碳排放量增加是否改变了与蚜虫抗性相关的叶蜡成分;假设3：捕食者和寄生虫的人口将遵循一个滞后的时间增加相应的更大的蚜虫人口在二氧化碳排放量，但相互干扰将阻碍觅食行为在最高蚜虫密度。该博士学位提案与农业食品研究的NERC开放案例优先领域高度一致，特别强调气候变化对害虫扩散的影响，通过模型作物的抗性破坏。这项研究的影响将是提供机械证据的多营养相互作用可能会改变气候变化。这将使作物育种者能够针对特定的植物抗性性状和生物控制措施，以适应气候变化下的作物生产。这直接有助于NERC战略计划，使社会能够紧急应对全球气候变化。该项目将通过调查气候变化将如何影响作物-食草动物-敌人的相互作用来实现LWEC的关键目标，并向负责适应和减缓气候变化的政策制定者提供及时的循证建议。