New paper published – A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling

Text by Lauri Laanisto

It´s a deeply methodological paper comparing the Rubisco responses measured in different ways. And more or less a follow-up paper to the one from last year, also led by Jeroni (link to blog post). A necessary stepping stone to put in place before big breakthroughs can be made. (Hopefully) soon…

Even though I had a hard time understanding the paper (although in the end I felt like I got some comprehension of the topic), I had a little part to play in this study. I carried out the phylogenetic analysis, showing that evolutionary background per se does not affect the Rubisco kinetics, it depends on species range, its photosynthetic mechanism, exact methods by which it was measured. It´s nice that sometimes the negative results can help coauthors out…

Citation: Galmés, J., Hermida-Carrera, C., Laanisto, L., & Niinemets, Ü. (2016). A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling. Journal of Experimental Botany, erw267.DOI: 10.1093/jxb/erw267 (link to full text)

Abstract:

The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis–Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kccat) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species’ climate and photosynthetic mechanism, with differences in ∆Ha for kccat among C3 plants from cool and warm environments, and in ∆Ha for kccat and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species’ growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species’ thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to realized photosynthesis.

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