title: Environmentally driven evolution of Rubisco and improved photosynthesis and growth within the C3 genus Limonium (Plumbaginaceae).
abstract: Carbon assimilation by most ecosystems requires ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Its kinetic parameters are likely to have evolved in parallel with intracellular CO2 availability, with the result that faster forms of Rubisco occur in species with CO2 -concentrating mechanisms. The Rubisco catalytic properties were determined and evaluated in relation to growth and carbon assimilation capacity in Mediterranean Limonium species, inhabiting severe stress environments. Significant kinetic differences between closely related species depended on two amino acid substitutions at functionally important residues 309 and 328 within the Rubisco large subunit. The Rubisco of species facing the largest CO2 restrictions during drought had relatively high affinity for CO2 (low Michaelis-Menten constant for CO2 Kc) but low maximum rates of carboxylation (kcatc), while the opposite was found for species that maintained higher CO2 concentrations under similar conditions. Rubisco kinetic characteristics were correlated with photosynthetic rate in both well-watered and drought-stressed plants. Moreover, the drought-mediated decrease in plant biomass accumulation was consistently lower in species with higher Rubisco carboxylase catalytic efficiency (kcatc/Kc). The present study is the first demonstration of Rubisco adaptation during species diversification within closely related C3 plants, revealing a direct relationship between Rubisco molecular evolution and the biomass accumulation of closely related species subjected to unfavourable conditions.
authors.affiliation: Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears, Balearic Islands, Spain.
authors.forename: Jeroni
authors.initials: J
authors.lastname: Galmés
authors.forename: P John
authors.initials: PJ
authors.lastname: Andralojc
authors.forename: Maxim V
authors.initials: MV
authors.lastname: Kapralov
authors.forename: Jaume
authors.initials: J
authors.lastname: Flexas
authors.forename: Alfred J
authors.initials: AJ
authors.lastname: Keys
authors.forename: Arántzazu
authors.initials: A
authors.lastname: Molins
authors.forename: Martin A J
authors.initials: MA
authors.lastname: Parry
authors.forename: Miquel À
authors.initials: MÀ
authors.lastname: Conesa
mesh_terms: D055162:Biocatalysis; D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D004777:Environment; D019143:Evolution, Molecular; D005843:Geography; D006239:Haplotypes; D007700:Kinetics; D008969:Molecular Sequence Data; D010788:Photosynthesis; D018515:Plant Leaves / Q000502:physiology; D029606:Plumbaginaceae / Q000201:enzymology* / Q000254:growth & development*; D021122:Protein Subunits / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism*; D013030:Spain; D013045:Species Specificity; D013696:Temperature
chemical_list: D021122:Protein Subunits; D002245:Carbon Dioxide; D002244:Carbon; D012273:Ribulose-Bisphosphate Carboxylase
keywords: Limonium; Mediterranean; Rubisco; carboxylase catalytic efficiency; drought; evolution; improved photosynthesis; water stress