title: C4 photosynthesis boosts growth by altering physiology, allocation and size.
abstract: C4 photosynthesis is a complex set of leaf anatomical and biochemical adaptations that have evolved more than 60 times to boost carbon uptake compared with the ancestral C3 photosynthetic type(1-3). Although C4 photosynthesis has the potential to drive faster growth rates(4,5), experiments directly comparing C3 and C4 plants have not shown consistent effects(1,6,7). This is problematic because differential growth is a crucial element of ecological theory(8,9) explaining C4 savannah responses to global change(10,11), and research to increase C3 crop productivity by introducing C4 photosynthesis(12). Here, we resolve this long-standing issue by comparing growth across 382 grass species, accounting for ecological diversity and evolutionary history. C4 photosynthesis causes a 19-88% daily growth enhancement. Unexpectedly, during the critical seedling establishment stage, this enhancement is driven largely by a high ratio of leaf area to mass, rather than fast growth per unit leaf area. C4 leaves have less dense tissues, allowing more leaves to be produced for the same carbon cost. Consequently, C4 plants invest more in roots than C3 species. Our data demonstrate a general suite of functional trait divergences between C3 and C4 species, which simultaneously drive faster growth and greater investment in water and nutrient acquisition, with important ecological and agronomic implications.
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Rebecca R L
authors.initials: RR
authors.lastname: Atkinson
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Mockford
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Bennett
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Pascal-Antoine
authors.initials: PA
authors.lastname: Christin
authors.affiliation: Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut 06520-8105, USA.
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Spriggs
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Robert P
authors.identifier: 0000-0002-8338-864X
authors.initials: RP
authors.lastname: Freckleton
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Ken
authors.initials: K
authors.lastname: Thompson
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Rees
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Colin P
authors.initials: CP
authors.lastname: Osborne
mesh_terms: D005075:Biological Evolution; D002244:Carbon / Q000378:metabolism*; D057486:Carbon Cycle; D010788:Photosynthesis; D018515:Plant Leaves / Q000254:growth & development / Q000502:physiology; D006109:Poaceae / Q000254:growth & development / Q000502:physiology*
chemical_list: D002244:Carbon