IRGA-Live Clamp: An integrated infrared gas-analysis platform to investigate systemic signalling within the plant canopy

持续的全球变暖正在剧烈地改变天气模式，每日和季节性的极端天气都限制了农作物的产量。解决这一问题的方法包括通过人为干预（例如灌溉、多水渠、受控环境农业）或通过引入基因编辑来优化作物的反应来缓解这一问题。然而，在每一种情况下，我们都缺乏对植物如何在有机体水平上对干预作出反应的理解。例如，在干旱的情况下（在温度较高的夏季更普遍），植物如何平衡水分保持与蒸发冷却和光合作用的需要？叶片表面的气孔在这种反应中起着至关重要的作用，植物通过整合多种环境信号来控制叶片内部与环境之间的气体交换。虽然单叶的行为已经被很好地理解，但我们还没有评估整个树冠对环境压力的反应。他们会在不同的叶子之间分配任务吗？这是如何协调的——植物的叶子能互相交谈吗？我们实验室的新结果表明，大豆叶片在热胁迫下打开气孔，但在热胁迫伴随着低湿度时关闭气孔。因此，在这种情况下，水分保持是优先考虑的。邻近的叶子，即使自己没有受到压力，也会对气孔行为的变化做出反应。这反映了一个被称为系统信号的过程，在这个过程中，非压力叶子“接收”来自压力“发送者”叶子的移动信号。令人惊讶的是，我们的研究结果表明，“接收叶”的反应不同，取决于它们是位于“发送叶”的上方还是下方，显示气孔打开或关闭。这些数据表明，植物的叶子可以相互交流，它们在冠层的不同部分之间分配任务。这种策略很可能会提高工厂的整体性能。然而，这些发现也提出了许多新的问题；信号是什么，为什么位置很重要，穿过树冠的自然光线梯度会改变反应和表现吗，疾病或害虫是如何干扰热量和干旱的系统信号的？我们如何量化潜在的收益？利用红外气体分析（IRGA）测量叶片中二氧化碳和水的交换，对植物的光合作用性能和气体交换进行常规监测。到目前为止，科学家们一次只使用一台IRGA机器来测量一棵植物一片叶子中的气体交换（或者用一个控制台控制的多路耳机测量几棵植物的气体交换）。我们将通过集成多个IRGA机器来推进最先进的技术，以实现对多个叶片的环境条件的单独控制，同时记录它们的气体交换和光合作用表现。至关重要的是，我们将应用网络技术来集成单个IRGA机器的功能。这将允许从一个叶子获得的数据驱动应用于其他叶子的协议。我们称之为“IRGA-Live Clamp”，类似于神经生理学中使用的类似方法。由于IRGA-Live Clamp平台的新颖性和回答重要研究问题的机会，来自英国各地的许多研究人员将有兴趣使用安装在格拉斯哥大学的IRGA-Live Clamp平台来调查不同的问题，促进新的合作。例如，我们将能够利用光遗传学专业知识来了解人工照明如何用于优化气体交换。因此，IRGA-Live Clamp平台将使科学知识取得重大进展，并帮助解决对植物抗逆性和农业至关重要的基本问题。因此，这笔资金将有助于气候变化下的粮食安全，并为英国的光合作用研究能力提供一个阶段性的变化。

Continued global warming is drastically changing weather patterns, with both daily and seasonal extremes that limit crop productivity. Approaches to address this problem include mitigation through human intervention (e.g. irrigation, polytunnels, controlled environment agriculture), or by introducing genetic editing to optimise crops' responses. However, in each of these cases we lack an understanding of how plants respond to the interventions at an organismal level. For example, in the presence of drought (more prevalent during the summer when temperatures are higher) how do plants balance water retention against the need for evaporative cooling and photosynthesis? Stomatal pores within the leaf surface are crucial in this response, with plants integrating multiple environmental signals to control gas exchange between the leaf interior and the environment. While the behaviour of single leaves is well understood, we have not assessed how the entire canopy responds to environmental stress. Do they divide up tasks between different leaves? How would this be co-ordinated - can plant leaves talk to each other? New results from our laboratories have shown that a soybean leaf opens the stomata under heat stress but closes them when heat stress is accompanied by low humidity. Thus, in this leaf water retention is prioritised. Neighbouring leaves, even if not stressed themselves, also react with changes in stomatal behaviour. This reflects a process called systemic signaling in which the non-stressed leaves 'receive' mobile signals from the stressed 'sender' leaf. Surprisingly, our findings indicate that 'receiver' leaves react differently depending on whether they are positioned above or below the 'sender' leaf, showing either stomatal opening or closure. These data demonstrate that plant leaves can communicate with each other, and they divide up tasks between different parts of the canopy. It is likely that this strategy improves the overall plant performance. However, the findings also pose many new questions; what are the signals, why does position matter, do natural gradients of light across the canopy alter responses and performance, how do disease or pests interfere with the systemic signaling of heat and drought? And how can we quantify the potential gains? Plant photosynthetic performance and gas exchange are routinely monitored using infrared gas analysis (IRGA) to measures the exchange of carbon dioxide and water across the leaf. Until now, scientists have used one IRGA machine at a time to measure gas exchange in one leaf in one plant (or in several plants with multiplexed headsets controlled from one console). We will advance the state of the art by integrating several IRGA machines to enable the individual control of environmental conditions in multiple leaves whilst simultaneously recording their gas exchange and photosynthetic performance. Crucially, we will apply networking technologies to integrate the functions of individual IRGA machines. This will allow data obtained from one leaf to drive protocols applied to other leaves. We call this 'IRGA-Live Clamp' in analogy to similar approaches used in neurophysiology. Due to the novelty of the IRGA-Live Clamp platform and the opportunities to answer important research questions many researchers from across the UK will be interested to use the IRGA-Live Clamp platform installed at the University of Glasgow to investigate different questions, fostering new collaborations. For example, we will be able to leverage optogenetic expertise to understand how artificial lighting can be used to optimise gas exchange. The IRGA-Live Clamp platform will therefore enable major progress in scientific knowledge and help solving fundamental questions that are important for plant stress tolerance and agriculture. The funds will therefore contribute to food security under climate change and provide a step-change in photosynthetic research capability within the UK.