6 research outputs found
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Recruitment of pre-existing networks during the evolution of C4 photosynthesis
During C4 photosynthesis, CO2 is concentrated around the enzyme RuBisCO. The net effect is to reduce photorespiration while increasing water and nitrogen use efficiencies. Species that use C4 photosynthesis have evolved independently from their C3 ancestors on more than 60 occasions. Along with mimicry and the camera-like eye, the C4 pathway therefore represents a remarkable example of the repeated evolution of a highly complex trait. In this review, we provide evidence that the polyphyletic evolution of C4 photosynthesis is built upon pre-existing metabolic and genetic networks. For example, cells around veins of C3 species show similarities to those of the C4 bundle sheath in terms of C4 acid decarboxylase activity and also the photosynthetic electron transport chain. Enzymes of C4 photosynthesis function together in gluconeogenesis during early seedling growth of C3 Arabidopsis thaliana. Furthermore, multiple C4 genes appear to be under control of both light and chloroplast signals in the ancestral C3 state. We, therefore, hypothesize that relatively minor rewiring of pre-existing genetic and metabolic networks has facilitated the recurrent evolution of this trait. Understanding how these changes are likely to have occurred could inform attempts to install C4 traits into C3 crops.CONACy
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Shared characteristics underpinning C leaf maturation derived from analysis of multiple C and C species of
Most terrestrial plants use C photosynthesis to fix carbon. In multiple plant lineages a modified system known as C photosynthesis has evolved. To better understand the molecular patterns associated with induction of C photosynthesis, the genus that contains C and C species was used. A base to tip maturation gradient of leaf anatomy was defined, and RNA sequencing was undertaken along this gradient for two C and two C species. Key C traits including vein density, mesophyll and bundle sheath cross-sectional area, chloroplast ultrastructure, and abundance of transcripts encoding proteins of C photosynthesis were quantified. Candidate genes underlying each of these C characteristics were identified. Principal components analysis indicated that leaf maturation and the photosynthetic pathway were responsible for the greatest amount of variation in transcript abundance. Photosynthesis genes were over-represented for a prolonged period in the C species. Through comparison with publicly available data sets, we identify a small number of transcriptional regulators that have been up-regulated in diverse C species. The analysis identifies similar patterns of expression in independent C lineages and so indicates that the complex C pathway is associated with parallel as well as convergent evolution.Seeds for all Flaveria species used were kindly provided by Udo Gowik (Universität Düsseldorf). The European Union 3to4 project and the Biotechnology and Biological Sciences Research Council (BBSRC) grant BB/J011754/1 funded the project
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Shared characteristics underpinning C leaf maturation derived from analysis of multiple C and C species of
Most terrestrial plants use C photosynthesis to fix carbon. In multiple plant lineages a modified system known as C photosynthesis has evolved. To better understand the molecular patterns associated with induction of C photosynthesis, the genus that contains C and C species was used. A base to tip maturation gradient of leaf anatomy was defined, and RNA sequencing was undertaken along this gradient for two C and two C species. Key C traits including vein density, mesophyll and bundle sheath cross-sectional area, chloroplast ultrastructure, and abundance of transcripts encoding proteins of C photosynthesis were quantified. Candidate genes underlying each of these C characteristics were identified. Principal components analysis indicated that leaf maturation and the photosynthetic pathway were responsible for the greatest amount of variation in transcript abundance. Photosynthesis genes were over-represented for a prolonged period in the C species. Through comparison with publicly available data sets, we identify a small number of transcriptional regulators that have been up-regulated in diverse C species. The analysis identifies similar patterns of expression in independent C lineages and so indicates that the complex C pathway is associated with parallel as well as convergent evolution.Seeds for all Flaveria species used were kindly provided by Udo Gowik (Universität Düsseldorf). The European Union 3to4 project and the Biotechnology and Biological Sciences Research Council (BBSRC) grant BB/J011754/1 funded the project