Temperature dependence of in vitro Rubisco kinetics in species of Flaveria with different photosynthetic mechanisms

Abstract

There is general consensus in the literature that plants with different photosynthetic mechanisms (i.e. C3 vs. C4) have Rubiscos characterised by different kinetic performances. However, potential differences in the temperature dependencies of Rubisco kinetic parameters between C3 and C4 plants are uncertain. Accordingly, six species of Flaveria with contrasting photosynthetic mechanisms (C3, C3/C4 and C4) were selected and their Rubisco Michaelis-Menten constants for CO2 and RuBP (K c and K RuBP), carboxylase catalytic turnover rate ([Formula: see text]) and CO2/O2 specificity factor (S c/o) were measured between 10 and 40 °C. The results confirmed different Rubisco characteristics between C3 and C4 plants. Rubisco from the C3 species had higher E a for K c and [Formula: see text] than that from C4 species, which were translated into differences in the temperature response of the carboxylase catalytic efficiency ([Formula: see text]/K c). However, E a did not differ for S c/o or K RuBP. Although a mechanism remains uncertain, it appears that the Asp/Glu-149-Ala and Met-309-Ile substitutions lead to differences in the temperature responses of catalysis between C3 and C4 Rubiscos in Flaveria. Therefore, the above observations are consistent with the fact that C3 species have a higher photosynthetic efficiency and ecological dominance in cool environments, with respect to C4 species in temperate environments.

Rubisco Catalytic Properties and Temperature Response in Crops

“…The k cat c from Z. mays and S. officinarum was 2-fold higher than that of the C 3 species, albeit at the expense of 3 times less affinity for CO 2 (Table I). This finding agrees with previously described trends between C 3 and C 4 species (Ghannoum et al, 2005;Kubien et al, 2008;Ishikawa et al, 2009) and with the fact that C 4 species present lower k cat c /K c Perdomo et al, 2015a).…”

“…The number and diversity of plant species for which Rubisco kinetic parameters have been tested in vitro at a range of physiologically relevant temperatures are still very scarce (Laing et al, 1974;Badger and Collatz, 1977;Badger, 1980;Monson et al, 1982;Hall and Keys, 1983;Jordan and Ogren, 1984;Lehnherr et al, 1985;Uemura et al, 1997;Zhu et al, 1998;Sage et al, 2002;Galmés et al, 2005;Haslam et al, 2005;Yamori et al, 2006;Perdomo et al, 2015a;Prins et al, 2016) and mostly restricted to a few kinetic parameters; actually, there is no study examining the temperature dependencies of the main kinetic constants in the same species. The limited data reported so far suggest the existence of interspecific differences in the temperature dependence of some Rubisco kinetic parameters, like k cat c (Chabot et al, 1972;Weber et al, 1977;Sage, 2002) or S c/o (Zhu et al, 1998;Galmés et al, 2005).…”

“…The limited data reported so far suggest the existence of interspecific differences in the temperature dependence of some Rubisco kinetic parameters, like k cat c (Chabot et al, 1972;Weber et al, 1977;Sage, 2002) or S c/o (Zhu et al, 1998;Galmés et al, 2005). Actually, differences in the energy of activation of k cat c and S c/o seem to be ascribed to the thermal conditions typically encountered by the species in their native habitat (Galmés et al, 2005) as well as to the photosynthetic mechanism (Perdomo et al, 2015a).…”

Surveying Rubisco diversity and temperature response to improve crop photosynthetic efficiency

“…Recent work has begun to make important inroads into this area (Perdomo et al, 2015;Prins et al, 2016). Analysis of the correlations between parameters at the three measurement temperatures largely agreed with previous observations regarding the trade-off between increasing carboxylation rate (k cat c ) and decreasing CO 2 affinity (increasing K c air ).…”

“…This is an important gap in our knowledge that will be important when targeting improvements to key crops. This study focused on C 3 species, and the potential for C 4 Rubiscos to respond differently has received increased interest recently (Boyd et al, 2015;Perdomo et al, 2015); however, there remains a need to characterize more Rubiscos from C 4 species for thermal response.…”