EAPSI: Phylogenetic Resolution and the Evolution of CAM Photosynthesis within Australian Calandrinia

该奖项支持旨在解决十字花科植物酸代谢(CAM)光合作用的物种关系和进化的研究，该属植物广泛分布于澳大利亚大陆，通常生活在干旱至半干旱环境中，尽管也从温带塔斯马尼亚和澳大利亚沿海以季风为主的热带地区采集了几个物种。CaM光合作用是一种在高温和干旱条件下提高光合作用和水分利用效率的适应。鉴于气候变化和世界日益干旱的S土地(约40%已被认为是干旱、半干旱或半湿润的土地)，我们有必要了解CAM光合作用的表达和演化，因为它可能在未来的碳固存、可持续生物质生产和粮食作物安全中发挥重要作用。这项研究将与澳大利亚多肉植物和CAM光合作用专家约瑟夫·霍尔图姆博士(James Cook University)合作进行。为了全面收集该属的标本，还与西澳植物标本馆、墨尔本植物园、澳大利亚热带植物标本馆和NT植物标本馆建立了更多的合作关系。自从C3光合作用的进化--大多数绿色植物使用的途径--以来，只有两种已知的替代途径进化：C4和CAM光合作用。这两个途径都提高了热/干和低CO2条件下的光合作用效率。关于C4光合作用的阶梯式进化已知很多，但对CAM的进化史及其系统发育分布知之甚少。这项研究将使用新的DNA测序技术来建立Calandrinia的强大的分子系统发育，该属代表了C3到CAM-中间(CAM-循环和兼性CAM)到CAM的光合作用光谱。为了表征光合作用的生理、同位素(13C/12C和D/H)，将在整个属内进行全面的测量。这些数据将根据分子系统学进行解释，以产生关于导致C3和CAM中间祖先的CAM表型组装的历史转变的假设。该NSF EAPSI奖是与澳大利亚科学院合作资助的。

This award supports research that aims to resolve the species relationships and the evolution of Crassulacean Acid Metabolism (CAM) photosynthesis within Calandrinia s.l., a genus of plants widely distributed across the Australian continent, typically inhabiting arid to semi-arid environments, although several species have also been collected from temperate Tasmania, and from the monsoon-dominated tropics of coastal Australia. CAM photosynthesis is an adaptation that improves photosynthetic and water use efficiency under hot and dry conditions. In light of climate change and the increasing aridity of the world?s land (~40% of which is already considered arid, semi-arid or sub-humid), it is necessary that we understand the expression and evolution of CAM photosynthesis as it will likely play an important role in the future of carbon sequestration, sustainable biomass production, and food-crop security. This research will be conducted in collaboration with Dr. Joseph Holtum (James Cook University), an expert on the succulent flora of Australia and CAM photosynthesis. In efforts to collect specimens comprehensively across the genus, additional collaborations have also been established with the WA Herbarium, Melbourne Botanic Garden, SA Herbarium, Australian Tropical Herbarium, and NT Herbarium.Since the evolution of C3 photosynthesis - the pathway used by most green plants - only two known alternative pathways have evolved: C4 and CAM photosynthesis. Both of these derived pathways improve photosynthetic efficiency under hot/dry and low CO2 conditions. Much is known about the step-like evolution of C4 photosynthesis but little is known about the evolutionary history of CAM and its phylogenetic distribution. This study will use novel DNA sequencing techniques to generate robust molecular phylogenies of Calandrinia, a genus that represents the C3 to CAM-intermediate (CAM-cycling and facultative CAM) to CAM photosynthetic spectrum. To characterize photosynthesis physiological, isotopic (13C/12C and D/H), and anatomical measurements will be comprehensively made across the genus. These data will be interpreted in light of the molecular phylogenies to generate hypotheses on the historical transformations leading to the assembly of the CAM phenotype from C3 and CAM-intermediate ancestors. This NSF EAPSI award is funded in collaboration with the Australian Academy of Science.