Article

C4 Photosynthesis Evolved in Grasses via Parallel Adaptive Genetic Changes

Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland.
Current Biology (Impact Factor: 9.57). 08/2007; 17(14):1241-7. DOI: 10.1016/j.cub.2007.06.036
Source: PubMed

ABSTRACT

Phenotypic convergence is a widespread and well-recognized evolutionary phenomenon. However, the responsible molecular mechanisms remain often unknown mainly because the genes involved are not identified. A well-known example of physiological convergence is the C4 photosynthetic pathway, which evolved independently more than 45 times [1]. Here, we address the question of the molecular bases of the C4 convergent phenotypes in grasses (Poaceae) by reconstructing the evolutionary history of genes encoding a C4 key enzyme, the phosphoenolpyruvate carboxylase (PEPC). PEPC genes belong to a multigene family encoding distinct isoforms of which only one is involved in C4 photosynthesis [2]. By using phylogenetic analyses, we showed that grass C4 PEPCs appeared at least eight times independently from the same non-C4 PEPC. Twenty-one amino acids evolved under positive selection and converged to similar or identical amino acids in most of the grass C4 PEPC lineages. This is the first record of such a high level of molecular convergent evolution, illustrating the repeatability of evolution. These amino acids were responsible for a strong phylogenetic bias grouping all C4 PEPCs together. The C4-specific amino acids detected must be essential for C4 PEPC enzymatic characteristics, and their identification opens new avenues for the engineering of the C4 pathway in crops.

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    • "Parallel genotypic evolution arises when mutations occur in independent lineages that start from the same genotype, whereas convergence refers to mutations produced from different ancestral genotypes (Zhang and Kumar 1997). Parallel and convergent genotypic evolution may arise at several levels: the same nucleotide mutating independently several times (Wichman 1999; Rozp ˛ edowska et al. 2011), different mutations in the same gene (Rosenblum et al. 2010) or in a multigene family (Christin et al. 2007; Srithayakumar et al. 2011), through mutations in different genes sharing the same function (Elias and Tawfik 2012) or in the same network (Lozovsky et al. 2009). Several experimental evolutions have now analyzed genomic parallelism and convergence . "
    Dataset: spor2013

    Full-text · Dataset · Sep 2015
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    • "Parallel genotypic evolution arises when mutations occur in independent lineages that start from the same genotype, whereas convergence refers to mutations produced from different ancestral genotypes (Zhang and Kumar 1997). Parallel and convergent genotypic evolution may arise at several levels: the same nucleotide mutating independently several times (Wichman 1999; Rozp ˛ edowska et al. 2011), different mutations in the same gene (Rosenblum et al. 2010) or in a multigene family (Christin et al. 2007; Srithayakumar et al. 2011), through mutations in different genes sharing the same function (Elias and Tawfik 2012) or in the same network (Lozovsky et al. 2009). Several experimental evolutions have now analyzed genomic parallelism and convergence . "
    Dataset: spor2013

    Full-text · Dataset · Sep 2015
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    • "Phylogenetic trees were inferred for the ppc and nadpme multigene families. The ppc-B1 and ppc-B2 markers were not included in the same dataset because these genes have very different GC contents and are subject to adaptive evolution, which can mislead the phylogenetic reconstructions (Christin et al., 2007). A phylogenetic tree was constructed separately for ppc-B2 based on 3rd positions of codons, which are less subject to selection. "
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    ABSTRACT: Collections of specimens held by natural history museums are invaluable material for biodiversity inventory and evolutionary studies, with specimens accumulated over 300 years readily available for sampling. Unfortunately, most museum specimens yield low-quality DNA. Recent advances in sequencing technologies, so called next-generation sequencing, are revolutionizing phylogenetic investigations at a deep level. Here, the Illumina technology (HiSeq) was used on herbarium specimens of Sartidia (subfamily Aristidoideae, Poaceae), a small African–Malagasy grass lineage (six species) characteristic of wooded savannas, which is the C3 sister group of Stipagrostis, an important C4 genus from Africa and SW Asia. Complete chloroplast and nuclear ribosomal sequences were assembled for two Sartidia species, one of which (S. perrieri) is only known from a single specimen collected in Madagascar 100 years ago. Partial sequences of a few single-copy genes encoding phosphoenolpyruvate carboxylases (ppc) and malic enzymes (nadpme) were also assembled. Based on these data, the phylogenetic position of Malagasy Sartidia in the subfamily Aristidoideae was investigated and the biogeographical history of this genus was analysed with full species sampling. The evolutionary history of two genes for C4 photosynthesis (ppc-aL1b and nadpme-IV) in the group was also investigated. The gene encoding the C4 phosphoenolpyruvate caroxylase of Stipagrostis is absent from S. dewinteri suggesting that it is not essential in C3 members of the group, which might have favoured its recruitment into a new metabolic pathway. Altogether, the inclusion of historical museum specimens in phylogenomic analyses of biodiversity opens new avenues for evolutionary studies.
    Full-text · Article · Sep 2014 · Journal of Experimental Botany
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