Sequencing the transcriptome of Kalanchoe fedtschenkoi: a model for Crassulacean acid metabolism embryogenic plantlet formation and the Saxifragales

长寿花转录组测序：景天酸代谢胚性植株形成和虎耳草目的模型

• 批准号: BB/F009313/1
• 负责人: James Hartwell
• 金额: $ 81.14万
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FF009313%2F1
• 关键词: Sequencing; transcriptome; Kalanchoe; fedtschenkoi; model

Plants have evolved three major forms of photosynthetic metabolism known as C3, C4 and Crassulacean acid metabolism (CAM). CAM is found in ~7 % of plant species, whilst C4 occurs in ~3 %. The remaining majority perform C3 photosynthesis. CAM and C4 improve the efficiency of plant water use; that is, the amount of water lost for each molecule of carbon dioxide converted into sugars in photosynthesis. CAM plants possess water-use efficiencies that can be 10-20 times greater than C3 plants. CAM is found in species that inhabit deserts, semi-arid or Mediterranean regions, and seasonally dry environments such as those on the branches of rain forest trees. Whilst whole genome sequencing projects have been completed for several plant species that perform C3 photosynthesis (Arabidopsis thaliana, rice and poplar) and a project is underway to sequence the genome of the C4 crop maize, there is very limited sequence information available for CAM species. It is therefore important that we sequence a CAM species so that we can complete the genomic picture of plant photosynthetic diversity. The Intergovernmental Panel on Climate Change (IPCC) report published this year predicts increasing desertification in already drought-prone regions of the world. CAM species can play an important role in mitigating the effects of climate change in arid and semi-arid zones, and there is now a pressing need to understand the molecular-genetic basis for CAM in order to capitalise on the utility of CAM plants fully. Importantly, our DNA sequencing proposal will unlock the genetic warehouse of novel genes that have evolved to enable plants to survive in desert and semi-arid environments. We will sequence the genes that are active in the leaf of a CAM plant. We will use Kalanchoe fedtschenkoi as our model system for this study. In 1961, an innovative young scientist called Malcolm Wilkins published a report in Nature showing a daily rhythm of carbon dioxide fixation in leaves of K. fedtschenkoi that persisted in constant conditions. This rhythm revealed that carbon dioxide fixation by the CAM pathway was under the control of an internal timekeeper known as a circadian clock. Circadian clocks keep time even in the absence of external environmental input and optimise the efficiency of photosynthesis and increase plant productivity. K. fedtschenkoi has continued to be a species in which significant scientific breakthroughs are made including advances in our understanding of the regulation of metabolic enzymes and the study of plant embryogenesis. K. fedtschenkoi is one of the best CAM species from which to sequence large amounts of genes for a number of reasons: (i) Unlike other CAM species, genes can be introduced into the K. fedtschenkoi genome using straightforward plant transformation procedures. This facet allows us to manipulate the activity of genes of interest and study their function in whole plants. (ii) There is a wealth of established whole plant physiology data for K. fedtschenkoi, which defines the physiological and biochemical details of the circadian rhythm of carbon dioxide fixation. (iii) The study of the biochemistry and molecular biology of CAM is routine in K. fedtschenkoi. There are established protocols for protein purification, enzyme assays and the isolation of pure DNA and RNA. In addition, K. fedtschenkoi is a member of a group of plants (known as the Saxifragales) that are of great interest to research groups working to understand the evolution of plant diversity. As already mentioned, genome sequence databases already exist for several plant species, but detailed gene sequence data is lacking for the Saxifragales. For this reason, our large-scale sequencing of genes from K. fedtschenkoi will provide a greatly needed resource of genetic information for this important group of plants that includes blackcurrants as well as many important garden species that are of great value to the horticultural trade.

植物的光合代谢主要有C3、C4和景天科酸代谢（CAM）三种形式。CAM存在于约7%的植物物种中，而C4存在于约3%。剩下的大多数进行C3光合作用。CAM和C4提高了植物水分利用的效率;也就是说，在光合作用中，每一个二氧化碳分子转化为糖所损失的水量。CAM植物的水分利用效率比C3植物高10-20倍。CAM存在于栖息在沙漠、半干旱或地中海地区的物种中，以及季节性干燥的环境中，如雨林树木的树枝上。虽然已经完成了几种进行C3光合作用的植物物种（拟南芥、水稻和白杨）的全基因组测序项目，并且正在进行C4作物玉米的基因组测序项目，但CAM物种的序列信息非常有限。因此，重要的是，我们对CAM物种进行测序，以便我们可以完成植物光合多样性的基因组图片。政府间气候变化专门委员会（IPCC）今年发表的报告预测，在世界上本已干旱的地区，荒漠化将日益加剧。CAM物种可以在缓解干旱和半干旱地区气候变化的影响方面发挥重要作用，现在迫切需要了解CAM的分子遗传基础，以便充分利用CAM植物的效用。重要的是，我们的DNA测序方案将打开新基因的遗传仓库，这些基因已经进化，使植物能够在沙漠和半干旱环境中生存。我们将对CAM植物叶片中活跃的基因进行测序。我们将使用Kalamae fedtschenkoi作为我们的模型系统进行这项研究。1961年，一位名叫马尔科姆·威尔金斯（Malcolm Wilkins）的年轻科学家在《自然》杂志上发表了一份报告，显示了K. fedtschenkoi坚持在恒定的条件。这种节律揭示了CAM途径对二氧化碳的固定是在被称为生物钟的内部计时器的控制下进行的。生物钟即使在没有外部环境输入的情况下也能保持时间，优化光合作用的效率，提高植物生产力。K. fedtschenkoi仍然是一个取得重大科学突破的物种，包括我们对代谢酶调节的理解和植物胚胎发生研究的进展。K. fedtschenkoi是从其测序大量基因的最佳CAM物种之一，原因如下：（i）与其它CAM物种不同，基因可以被引入到K. fedtschenkoi的基因组，使用简单的植物转化程序。这一方面使我们能够操纵感兴趣的基因的活性，并研究它们在整个植物中的功能。(ii)K. fedtschenkoi，其定义了二氧化碳固定的昼夜节律的生理和生化细节。(iii)CAM的生物化学和分子生物学研究是K. fedtschenkoi。已经建立了蛋白质纯化、酶测定和纯DNA和RNA分离的方案。此外，K. fedtschenkoi是一组植物（称为虎耳草目）的成员，这组植物对致力于了解植物多样性进化的研究小组非常感兴趣。如前所述，几种植物的基因组序列数据库已经存在，但缺乏虎耳草的详细基因序列数据。因此，我们对K. fedtschenkoi将为这一重要的植物群提供急需的遗传信息资源，这一植物群包括黑醋栗以及许多对园艺贸易具有重要价值的重要园林物种。

项目成果

Engineering crassulacean acid metabolism to improve water-use efficiency.

• DOI: 10.1016/j.tplants.2014.01.006
• 发表时间: 2014-05
• 期刊: TRENDS IN PLANT SCIENCE
• 影响因子: 20.5
• 作者: Borland, Anne M.;Hartwell, James;Weston, David J.;Schlauch, Karen A.;Tschaplinski, Timothy J.;Tuskan, Gerald A.;Yang, Xiaohan;Cushman, John C.
• 通讯作者: Cushman, John C.

Parallel recruitment of multiple genes into c4 photosynthesis.

• DOI: 10.1093/gbe/evt168
• 发表时间: 2013
• 期刊: Genome biology and evolution
• 影响因子: 3.3
• 作者: Christin PA;Boxall SF;Gregory R;Edwards EJ;Hartwell J;Osborne CP
• 通讯作者: Osborne CP