EAGER: Elucidation of the Potential for CAM Photosynthesis in the C4 Halophyte Spinifex littoreus, a Succulent Asian Grass with Enormous Agricultural Potential

EAGER：阐明 C4 盐生植物 Spinifex littoreus（一种具有巨大农业潜力的多汁亚洲草）的 CAM 光合作用潜力

• 批准号: 1411897
• 负责人: Craig Martin
• 金额: $ 27.99万
• 依托单位: University of Kansas Center for Research Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-15 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1411897&HistoricalAwards=false
• 关键词: EAGER; Elucidation; Potential; CAM; Photosynthesis

Recently, the PI and international collaborators discovered that a coastal grass in Taiwan has a very unusual type of photosynthesis, the mechanism that plants use to make food (theirs and ours). This type of photosynthesis has only been found in one other small group of plants, and scientists are still puzzled by its significance. This discovery is particularly interesting because the plant is a grass, and one consequence of its unusual type of photosynthesis is a considerable savings of water. These two observations become even more interesting from an agricultural perspective because most of the world?s grain crops derive from grasses, and irrigation of such grasses is depleting world reservoirs/aquifers and creating difficulties wherever such water demands exceed supply. The grass that is the focus of the proposed research may well provide a source of the genetic underpinnings for conserving water and reducing irrigation demands worldwide. The immediate work proposed by the PI comprises field and laboratory investigations of the unusual photosynthesis in this grass with the goal of determining under what conditions it most expresses its water-conservative physiology. This research lays the groundwork for further genetic and agricultural work.Although species with CAM photosynthesis are now known from over 30 different plant families, no species in one of the largest extant families, the Poaceae (grasses), has been reported as having CAM. Preliminary research by the PI and his colleagues, however, has discovered variable levels of Crassulacean Acid Metabolism (CAM) in the succulent halophytic grass, Spinifex littoralis, a C4 species that grows in coastal areas throughout Southeast Asia. This is the first known report of succulence and of CAM in a species of Poaceae. The goals of the proposed research are to determine why CAM is variable and which environmental factors are most important in promoting the greatest degree of CAM in this succulent C4 grass. Diurnal patterns of leaf gas exchange, titratable acidity, and PEP carboxylase activity will be monitored in the field and in the lab under varying conditions of irradiance, water status, and soil salinity. Plants for these investigations will be sampled from different populations in different habitats in Taiwan, including those with and without competitors. Other measurements to be made include light-use efficiency using PAM fluorometry, leaf tissue anatomy (especially degree of succulence), and leaf water potential. In addition, the proposed research, in collaboration with molecular plant physiologists, includes preliminary work designed to determine how best to prepare use of this plant for genetic purposes with the goal of transferring CAM genes to agricultural grain species.

最近，PI和国际合作者发现台湾的一种沿海草具有一种非常不寻常的光合作用，这是植物用来制造食物的机制（他们和我们）。 这种类型的光合作用只在另一小群植物中发现，科学家们仍然对它的意义感到困惑。 这一发现特别有趣，因为这种植物是一种草，其不寻常的光合作用类型的一个结果是相当多的水。 从农业的角度来看，这两个观察结果变得更加有趣，因为世界上大多数国家？世界上的粮食作物来自于草，而对这些草的灌溉正在耗尽世界上的水库/蓄水层，并在这种水需求超过供应的地方造成困难。 作为拟议研究重点的草很可能为保护水资源和减少全球灌溉需求提供遗传基础。 PI提出的立即工作包括对这种草不寻常的光合作用进行实地和实验室调查，目的是确定在什么条件下它最能表达其保水生理学。 这项研究为进一步的遗传学和农业工作奠定了基础。尽管现在已知有30多个不同的植物科具有CAM光合作用的物种，但在现存最大的科之一的禾本科（禾本科）中没有任何物种被报道具有CAM。 然而，PI和他的同事的初步研究发现，在肉质盐生草Spinifex littoralis中存在不同水平的景天科酸代谢（CAM），Spinifex littoralis是一种生长在东南亚沿海地区的C4物种。这是首次报道禾本科植物的肉质和CAM。拟议的研究的目标是确定为什么CAM是可变的，哪些环境因素是最重要的，以促进最大程度的CAM在这个多汁的C4草。 在不同的光照、水分状况和土壤盐分条件下，将在田间和实验室监测叶片气体交换、可滴定酸度和PEP羧化酶活性的日变化模式。 这些调查的植物将从台湾不同生境的不同种群中取样，包括有竞争者和没有竞争者的植物。其他测量包括光利用效率使用PAM荧光，叶组织解剖（特别是多汁程度），和叶水势。此外，拟议的研究，与分子植物生理学家合作，包括初步工作，旨在确定如何最好地准备使用这种植物的遗传目的，目的是转移CAM基因到农业谷物物种。