Drought responses of C4 plants: resolving the effects of physiological pathway from phylogenetic history

C4植物的干旱反应：从系统发育史解析生理途径的影响

• 批准号: NE/D013062/1
• 负责人: Colin Osborne
• 金额: $ 45.76万
• 依托单位: University of Sheffield
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FD013062%2F1
• 关键词: Drought; responses; C4; plants; resolving

Plants using the C4 photosynthetic pathway dominate grassland ecosystems and cereal production in warm climates. Both the multiple evolutionary origins and abrupt geological shifts in the ecological dominance of this group have been linked with changes in atmospheric CO2 and climate. C4 plant responses to global change are therefore of fundamental importance for ecosystem resource management under anthropogenic climate change and for understanding the Earth System, both key scientific objectives for NERC. In recent years, attention has shifted from atmospheric CO2 towards water availability as a key driver of C4 plant responses to past and future atmospheric change, reinstating major unanswered questions about C4 plant-aridity relationships as research priorities. Crucially, if C4 photosynthesis is more efficient in its use of water than the C3 type, why does the fraction of species with the NADP-ME C4 sub-type decline in grass floras as rainfall decreases, whereas species with the NAD-ME sub-type show the opposite pattern? Do some sub-types of C4 photosynthesis confer drought tolerance, whilst others are linked with drought sensitivity? Or are these correlations unrelated to the inherent properties of C4 photosynthesis, but instead linked with the traits characterising the independent plant lineages where the C4 pathway originated? The proposed project aims to resolve these physiological and phylogenetic components of C4 plant water relations by linking experimental, model and field investigations within the framework of new molecular genetic classifications. Our first hypothesis, that there is a direct effect of C4 physiology on plant drought tolerance, will be tested with phylogenetically controlled experiments using congeneric C3/C4 species pairs, each representing independent C4 photosynthetic origins across monocot and eudicot groups. Controlled environment experiments have been designed within the framework of a new mechanistic model of stomatal control to develop an integrated picture of how C4 physiology per se influences plant water relations under drought. Our second hypothesis, that there is an important phylogenetic component to drought tolerance in the C4 grasses, will be tested within the PACCAD Clade, which encompasses all of the world's C4 grasses and at least four independent origins for the C4 pathway. The interaction of physiological and phylogenetic hypotheses will be quantified by extending the screening analysis to C3 groups nested within the same clade. Experiments will target key plant traits determining water uptake, transport and loss, and desiccation tolerance to test the contrasts between C3 and C4 types, NADP-ME and NAD-ME sub-types, independent grass clades, and their interactions. A multi-factorial common garden experiment in South Africa will examine the implications of these interactions for productivity and water-use in natural climate and soil conditions, using a sub-sample of the NADP-ME C4 and C3 species which together comprise a major part of the southern African grass flora.

在温暖气候下，利用C4光合途径的植物主导着草地生态系统和谷物生产。这一群体的多重进化起源和生态优势的突变地质变化都与大气二氧化碳和气候的变化有关。因此，C4植物对全球变化的响应对于人为气候变化下的生态系统资源管理和对地球系统的理解具有重要意义，这两者都是NERC的关键科学目标。近年来，人们的注意力已经从大气CO2转移到作为C4植物对过去和未来大气变化响应的关键驱动因素的水分有效性，并将C4植物与干旱关系的主要未解问题重新作为研究重点。至关重要的是，如果C4光合作用比C3光合作用更有效地利用水分，为什么随着降雨量的减少，NADP-ME C4亚型的物种比例会下降，而NADP-ME亚型的物种却表现出相反的模式？C4光合作用的某些亚型是否具有耐旱性，而其他亚型则与干旱敏感性有关？或者这些相关性与C4光合作用的固有特性无关，而是与C4途径起源的独立植物谱系的特征有关？该项目旨在通过在新的分子遗传分类框架内将实验、模型和实地调查联系起来，解决C4植物水分关系的生理和系统发育成分。我们的第一个假设，即C4生理对植物抗旱性有直接影响，将通过系统发育控制实验进行验证，使用同源的C3/C4物种对，每个物种对代表单子叶和双子叶植物群中独立的C4光合起源。在一个新的气孔控制机制模型框架内设计了受控环境实验，以开发C4生理学本身如何影响干旱下植物水分关系的综合图景。我们的第二个假设，即C4草的耐旱性存在一个重要的系统发育成分，将在PACCAD分支中进行测试，该分支包括世界上所有C4草和C4途径的至少四个独立起源。通过将筛选分析扩展到嵌套在同一分支中的C3组，将对生理和系统发育假设的相互作用进行量化。实验将针对植物的关键性状，包括水分吸收、运输和损失以及干燥耐受性，测试C3和C4类型、NADP-ME和NADP-ME亚型、独立草枝的差异及其相互作用。南非的一项多因子普通花园实验将使用NADP-ME C4和C3物种的子样本，研究这些相互作用在自然气候和土壤条件下对生产力和水资源利用的影响，这些物种共同构成了南部非洲草区系的主要部分。

项目成果

Developmental and biophysical determinants of grass leaf size worldwide

• DOI: 10.1038/s41586-021-03370-0
• 发表时间: 2021-03-24
• 期刊: NATURE
• 影响因子: 64.8
• 作者: Baird, Alec S.;Taylor, Samuel H.;Sack, Lawren
• 通讯作者: Sack, Lawren

Physiological advantages of C4 grasses in the field: a comparative experiment demonstrating the importance of drought.

• DOI: 10.1111/gcb.12498
• 发表时间: 2014-06
• 期刊: Global change biology
• 影响因子: 11.6
• 作者: Taylor SH;Ripley BS;Martin T;De-Wet LA;Woodward FI;Osborne CP
• 通讯作者: Osborne CP