Physiology and toxicology of ion fluxes in plant roots

植物根部离子通量的生理学和毒理学

• 批准号: RGPIN-2014-05650
• 负责人: Kronzucker, Herbert
• 金额: $ 4.3万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=588534
• 关键词: Physiology; toxicology; ion; fluxes; plant

My laboratory is dedicated to the exploration of transport systems in plants, and the relationship between transport pathways and plant productivity. My many discoveries in this area have proven to be of fundamental interest to a broad scientific community, having been published in Nature, PNAS, and Trends in Plant Science, and garnered over 4300 citations. I have also dedicated my work to the greater public, through public lectures, news media and personal outreach, and especially through my involvement with such groups as the International Rice Research Institute, and my own initiative, the Canadian Centre for World Hunger Research. These activities and accomplishments, among many others, have been made possible by the core operating funds consistently provided to my research program by NSERC. The research proposed here will advance our knowledge of root ion transport, mineral acquisition and toxicity, and plant growth, in the Arabidopsis model plant and in agriculturally important cereal grasses. Discovery will focus on the transport physiology of potassium (K+), sodium (Na+), and ammonium/ammonia (NH4+/NH3), with emphasis on their relation to growth, and their interactions with each other, and with water and other soil ions. While this is fundamental science, innovation in my research area has great potential for improvements in plant productivity. Of these soil components, K+ is the best studied, but new frontiers await discovery in the area of plant-K+ relations. We will examine the full complement of K+ transporters, in particular those operating when the main systems are compromised genetically and/or physiologically. We will also explore the poorly understood mechanisms underlying the interactions between K+ nutrition and NH4+/NH3 and Na+ stresses, and we will investigate the fundamental links between K+ nutrition and plant water use, especially in the context of aquaporin (water channel) activity. Discoveries in this area will help address the massive water footprint of agriculture, particularly in rice, the world's thirstiest crop. My laboratory has long specialized in plant-nitrogen relations, particularly nutritional and toxicological aspects of NH4+/NH3 provision. We have recently demonstrated that NH3 is the main permeating form of the conjugate pair under toxicity, and that its transport into plant cells is likely mediated by aquaporins. NH4+/NH3 toxicity may thus be directly tied to water flow, suggesting a new mechanism for its alleviation by K+. We are now at a critical juncture of finding the fundamental nature of this toxicity, in relation to the primary transport of NH3, and its dependence on the presence of other nutrients and stresses. My group has also recently made substantial progress in the area of sodium transport and toxicity, fundamentally revising the mechanistic model describing this important phenomenon. Many aspects of Na+ transport are still poorly understood, as are the exact mechanisms of Na+ toxicity. How much Na+ enters cells, and how much accumulates outside? Does Na+ target cell expansion, division, or disintegration? Can cellular Na+ accumulation be beneficial, even under toxicity? Can Na+ toxicity be ameliorated by reducing solute flow through the root apoplast? In addition to pursuing discovery in these critical areas, I propose to develop a leading-edge program in the epigenetics of plant nutrition, about which virtually nothing is known. I will ask how the rearing of plants influences the water and nutrient use of their descendants, and how such inheritance patterns manifest at a molecular level. How does such nutritional prehistory affect plant resistance to mineral toxicities, and can this approach be beneficial to out-planting strategies in nutrient-poor or saline soils?

我的实验室致力于探索植物中的运输系统，以及运输途径与植物生产力之间的关系。我在这一领域的许多发现已被证明是广泛的科学界的根本利益，已发表在自然，PNAS和植物科学趋势，并获得超过4300引用。我还通过公开讲座、新闻媒体和个人外联，特别是通过参与国际水稻研究所等团体以及我自己发起的加拿大世界饥饿研究中心，致力于为广大公众开展工作。这些活动和成就，以及其他许多活动和成就，都是由NSERC持续为我的研究计划提供的核心运营资金所实现的。 这里提出的研究将推进我们的知识根离子运输，矿物质的收购和毒性，植物生长，在拟南芥模式植物和农业上重要的禾本科牧草。发现将侧重于钾（K+），钠（Na+）和铵/氨（NH 4 +/NH3）的运输生理学，重点是它们与生长的关系，以及它们之间的相互作用，以及与水和其他土壤离子的相互作用。虽然这是基础科学，但我的研究领域的创新对提高植物生产力有很大的潜力。 在这些土壤成分中，K+是研究得最好的，但在植物-K+关系领域还有待发现新的前沿。我们将研究K+转运蛋白的全部补充，特别是当主要系统在遗传和/或生理上受到损害时的那些转运蛋白。我们还将探索K+营养和NH 4 +/NH3和Na+胁迫之间相互作用的机制，我们将研究K+营养和植物水分利用之间的基本联系，特别是在水通道蛋白（水通道）活性的背景下。这一领域的发现将有助于解决农业的巨大水足迹，特别是世界上最缺水的作物水稻。 我的实验室长期专注于植物氮的关系，特别是NH 4 +/NH3供应的营养和毒理学方面。我们最近已经证明，NH3是主要的渗透形式的共轭对下的毒性，其运输到植物细胞可能是由水通道蛋白介导的。因此，NH 4 +/NH3毒性可能与水流直接相关，这表明K+减轻NH 4 +/NH3毒性的新机制。我们现在正处于一个关键时刻，发现这种毒性的基本性质，与NH3的主要运输，以及它对其他营养物质和压力的依赖。 我的小组最近在钠转运和毒性领域也取得了实质性进展，从根本上修改了描述这一重要现象的机制模型。Na+转运的许多方面仍然知之甚少，Na+毒性的确切机制也是如此。有多少Na+进入细胞，又有多少在细胞外积累？Na+是否靶向细胞扩增、分裂或解体？细胞内Na+积累是否有益，即使在毒性下？Na+毒害可以通过减少溶质流经根质外体来改善吗？ 除了在这些关键领域进行探索之外，我还建议在植物营养的表观遗传学方面开发一个领先的项目，对此几乎一无所知。我将询问植物的饲养如何影响其后代对水和养分的利用，以及这种遗传模式如何在分子水平上表现出来。这种营养史前史如何影响植物对矿物质毒性的抵抗力，这种方法是否有利于营养贫乏或盐碱土壤中的外植策略？