Oligocene CO2 decline promoted C4 photosynthesis in grasses
Oligocene CO2 decline promoted C4 photosynthesis in grasses
复制标题
渐新世二氧化碳下降促进了禾本科植物的 C4 光合作用
DOI：
10.1016/j.cub.2007.11.058
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发表时间：
2008-01-08
期刊：
影响因子：
9.2
通讯作者：
Salamin, Nicolas
中科院分区：
文献类型：
--
作者：
Christin, Pascal-Antoine;Besnard, Guillaume;Salamin, Nicolas
C-4光合作用是一种适应，源于更常见的C-3光合作用途径，该途径在温暖的温度和低大气CO2浓度下提供更高的生产力[1，2]。C-4的演化被认为是过去大气二氧化碳下降的结果，例如3200万-2500万年前(Mya)的二氧化碳突然下降[3-6]。这种关系从来没有经过严格的测试，主要是因为缺乏对不同C-4谱系的分歧时间的准确估计[3]。在这项研究中，我们推断了禾本科的系统发育树，并通过贝叶斯分子测年估计了17到18个独立的禾本科C4谱系的年龄。从C-3到C-4的第一次光合作用发生在金龟亚科的32.0-25.0Mya。用一种新的最大似然法检验了二氧化碳减少与向C-4光合作用转变之间的联系。结果表明，考虑大气CO2浓度的模型显著优于零模型，支持了CO2下降对C-4光合作用演化的重要性。这一发现与理解草的C-4光合作用的起源有关，C-4光合作用是植物史上最成功的生态和进化创新之一。
C-4 photosynthesis is an adaptation derived from the more common C-3 photosynthetic pathway that confers a higher productivity under warm temperature and low atmospheric CO2 concentration [1, 2]. C-4 evolution has been seen as a consequence of past atmospheric CO2 decline, such as the abrupt CO2 fall 32-25 million years ago (Mya) [3-6]. This relationship has never been tested rigorously, mainly because of a lack of accurate estimates of divergence times for the different C-4 lineages [3]. In this study, we inferred a large phylogenetic tree for the grass family and estimated, through Bayesian molecular dating, the ages of the 17 to 18 independent grass C4 lineages. The first transition from C-3 to C-4 photosynthesis occurred in the Chloridoideae subfamily, 32.0-25.0 Mya. The link between CO2 decrease and transition to C-4 photosynthesis was tested by a novel maximum likelihood approach. We showed that the model incorporating the atmospheric CO2 levels was significantly better than the null model, supporting the importance Of CO2 decline on C-4 photosynthesis evolvability. This finding is relevant for understanding the origin Of C-4 photosynthesis in grasses, which is one of the most successful ecological and evolutionary innovations in plant history.