Watching C4 photosynthesis evolve! Does Salsola divaricata, a C2 species on the Canary Islands, bridge the complex evolutionary transition between C3 and C4 photosynthesis?

观察 C4 光合作用的进化！

• 批准号: 282807155
• 负责人: Professorin Dr. Gudrun Kadereit
• 金额: --
• 依托单位: Bereich Systematik, Biodiversität & Evolution der Pflanzen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/282807155?language=en
• 关键词: Watching; C4; photosynthesis; evolve; Does

C4 photosynthesis (PS) is a complex trait and its evolution requires profound changes of leaf anatomy and ultrastructure, pathway biochemistry and gene regulation within the ancestral C3 lineage. C4 PS arose c. 65 times in the angiosperms with one hotspot of c. 15 origins in the Chenopodiaceae. The processes of how C4 PS evolved are still a mystery. Conceptual models of C4 evolution always favoured a gradual, stepwise transition from C3 to C4 with the glycine shuttle carbon concentrating mechanisms (C2 PS) as the key step (originally proposed by Monson et al. (1984); modified by Sage et al. 2012). The empirical evidence that supports the model has a number of limitations, most importantly the flaw that phenotypic plasticity and variation of traits at the population level has never been taken into account. To test the current model of C4 evolution this grant proposal suggests to study the C2 species Salsola divaricata from the Canary Islands and the two closely related C3 species S. verticillata and S. gymnomaschala from SW Morocco in which hypothetical early phases of C4 photosynthesis evolution appear to be present. The study includes an assessment of the genetic differentiation among 16 populations of Salsola divaricata and its closest relatives from SW Morocco using the next generation sequencing method genotyping by sequencing, local climate and edaphic parameters and a survey of C4-relevant traits as proposed by the model. These are quantitative assays of C2 and C4 proteins, carbon compensation point measurements, expression patterns of C2 and C4 enzymes in leaf cross sections and bundle sheath ultrastructure. A transcriptome analysis of selected samples with deviating trait expression will furthermore reveal differentiation and/or plasticity at the gene regulatory level. The phenotypic variation of C4 traits in Salsola divaricata might represent distinct genetically fixed evolutionary states of C4 evolution and therefore support the current model or it might be a fascinating case of broad phenotypic plasticity of a complex physiological syndrome and stimulate a fundamental re-evaluation of the current model towards a concept that includes phenotypic plasticity. To understand the evolution of the highly complex trait C4 PS is not only to disentangle a fascinating biological problem of broad interest but also a hot topic in current research efforts to introduce the C4 pathway into C3 crops such as rice.

C4 光合作用 (PS) 是一个复杂的性状，其进化需要祖先 C3 谱系内叶片解剖结构和超微结构、途径生物化学和基因调控的深刻变化。 C4 PS 出现 c。在被子植物中，有 65 次，其中一个热点为 c。 15 起源于藜科。 C4 PS如何进化的过程仍然是个谜。 C4进化的概念模型总是倾向于从C3到C4的逐步过渡，以甘氨酸穿梭碳浓缩机制（C2 PS）作为关键步骤（最初由Monson等人（1984）提出；由Sage等人修改，2012）。支持该模型的经验证据有许多局限性，最重要的是从未考虑到群体水平的表型可塑性和性状变异的缺陷。为了测试当前的 C4 进化模型，该拨款提案建议研究来自加那利群岛的 C2 物种 Salsola divaricata 和来自摩洛哥西南部的两个密切相关的 C3 物种 S. verticillata 和 S.gynomomaschala，其中似乎存在 C4 光合作用进化的假设早期阶段。该研究包括使用下一代测序方法对来自摩洛哥西南部的 16 个猪毛菜种群及其近亲之间的遗传分化进行评估，通过测序、当地气候和土壤参数进行基因分型，并对模型提出的 C4 相关性状进行调查。这些是 C2 和 C4 蛋白的定量测定、碳补偿点测量、叶横截面和束鞘超微结构中 C2 和 C4 酶的表达模式。对具有偏差性状表达的选定样本进行转录组分析将进一步揭示基因调控水平上的分化和/或可塑性。 Salsola divaricata 中 C4 性状的表型变异可能代表了 C4 进化的不同遗传固定进化状态，因此支持当前模型，或者它可能是复杂生理综合征的广泛表型可塑性的一个令人着迷的案例，并刺激对当前模型的基本重新评估，以实现包括表型可塑性的概念。了解高度复杂性状 C4 PS 的进化不仅是为了解决一个引起广泛关注的令人着迷的生物学问题，也是当前将 C4 途径引入水稻等 C3 作物的研究工作的热门话题。