Exploring molecular evolution of Rubisco in C3 and CAM Orchidaceae and Bromeliaceae

Abstract

Background: The CO 2-concentrating mechanism associated to Crassulacean acid metabolism (CAM) alters the catalytic context for Rubisco by increasing CO 2 availability and provides an advantage in particular ecological conditions. We hypothesized about the existence of molecular changes linked to these particular adaptations in CAM Rubisco. We investigated molecular evolution of the Rubisco large (L-) subunit in 78 orchids and 144 bromeliads with C 3 and CAM photosynthetic pathways. The sequence analyses were complemented with measurements of Rubisco kinetics in some species with contrasting photosynthetic mechanism and differing in the L-subunit sequence. Results: We identified potential positively selected sites and residues with signatures of co-adaptation. The implementation of a decision tree model related Rubisco specific variable sites to the leaf carbon isotopic composition of the species. Differences in the Rubisco catalytic traits found among C 3 orchids and between strong CAM and C 3 bromeliads suggested Rubisco had evolved in response to differing CO 2 concentration. Conclusions: The results revealed that the variability in the Rubisco L-subunit sequence in orchids and bromeliads is composed of coevolving sites under potential positive adaptive signal. The sequence variability was related to δ 13 C in orchids and bromeliads, however it could not be linked to the variability found in the kinetic properties of the studied species.

Recent advances in understanding and improving photosynthesis

“…Hermida-Carrera et al . 26 found similar results when comparing rubisco catalytic traits of orchids and bromeliads with and without CCMs. These results suggest that equipping C 3 crops with CCMs could be another strategy for fueling their photosynthetic capacity.…”

Extremely low nucleotide diversity among thirty-six new chloroplast genome sequences fromAldama(Heliantheae, Asteraceae) and comparative chloroplast genomics analyses with closely related genera

“…Positive selection for rbcL is widespread among land plants ( Kapralov & Filatov, 2007 ; Yao et al, 2019 ; Shen et al, 2020 ) and several studies have demonstrated that positive selection on specific amino-acids in rubisco is linked to plant adaptation to different environmental stresses, facilitating adaptive radiation into diverse ecological niches ( Hermida-Carrera et al, 2017 ). Examples include adaptations to dry or wet climates ( Kapralov & Filatov, 2006 ; Galmés et al, 2014 ), to high altitude environments ( Hu et al, 2015 ) and in transitions from C 3 to C 4 photosynthesis ( Christin et al, 2008 ; Kapralov, Smith & Filatov, 2012 ; Hermida-Carrera et al, 2020 ), including in Flaveria (Asteraceae, tribe Tageteae) ( Kapralov et al, 2011 ).…”

Setting the evolutionary timeline: Tillandsia landbeckii in the Chilean Atacama Desert

“…The T. purpurea accession grouped together with one T. marconae and all T. landbeckii accessions might have captured its plastome via reticulate evolutionary processes. The second T. marconae accession (HEID103591/ Rauh20899) has been analyzed earlier in a broader context of the evolution of CAM metabolism in Bromeliaceae (Hermida-Carrera et al 2020). For this taxon and respective accession CAM metabolisms has been confirmed and maternal phylogenetic affinity with T. purpurea has been documented sequencing the rbcL gene (Hermida-Carrera et al 2020).…”