RuBisCO adaptation is more limited by phylogenetic constraint than by catalytic trade-off in plants

RuBisCO assimilates CO2 to form the sugars that fuel life on earth. Correlations between RuBisCO kinetic traits across species have led to the proposition that RuBisCO adaptation is constrained by catalytic trade-offs. However, these analyses did not consider the phylogenetic context of the enzymes that were analysed. Thus, it is possible that the observed correlations between RuBisCO kinetic traits are an artefact of the presence of phylogenetic signal in RuBisCO kinetics and the phylogenetic relationship between the species that were sampled. Here, we conducted a phylogenetically resolved analysis of RuBisCO kinetics and show that there is significant phylogenetic signal in all carboxylase kinetic traits, and significant phylogenetic signal in the Michaelis constant for O2 in species that conduct C3 photosynthesis. When accounting for this phylogenetic non-independence between enzymes, we show that the catalytic trade-off between carboxylase turnover and the Michaelis constant for CO2 is weak (~30 % dependency) and that the correlations between all other RuBisCO kinetic traits are either not-significant or marginal (