Dynamic photo‐inhibition and carbon gain in a C₄and a C₃grass native to high latitudes

Abstract

C 4 plants are rare in the cool climates characteristic of high latitudes and altitudes, perhaps because of an enhanced susceptibility to photo-inhibition at low temperatures relative to C 3 species. In the present study we tested the hypothesis that low-temperature photo-inhibition is more detrimental to carbon gain in the C 4 grass Muhlenbergia glomerata than the C 3 species Calamogrostis Canadensis . These grasses occur together in boreal fens in northern Canada. Plants were grown under cool (14/10 ∞ ∞ ∞ ∞ C day/night) and warm (26/22 ∞ ∞ ∞ ∞ C) temperatures before measurement of the light responses of photosynthesis and chlorophyll fluorescence at different temperatures. Cool growth temperatures led to reduced rates of photosynthesis in M. glomerata at all measurement temperatures, but had a smaller effect on the C 3 species. In both species the amount of xanthophyll cycle pigments increased when plants were grown at 14/10 ∞ ∞ ∞ ∞ C, and in M. glomerata the xanthophyll epoxidation state was greatly reduced. The detrimental effect of low growth temperature on photosynthesis in M. glomerata was almost completely reversed by a 24-h exposure to the warm-temperature regime. These data indicate that reversible dynamic photo-inhibition is a strategy by which C 4 species may tolerate cool climates and overcome the Rubisco limitation that is prevalent at low temperatures in C 4 plants.

Photosynthetic, hydraulic and biomass properties in closely related C3 and C4 species

“…bidentis plants saturated at much lower irradiances. Superior net photosynthetic rates of C 4 were also evident in a comparison between the cold adapted co‐occurring C 3 Calamogrostis canadensis and C 4 Muhlenbergia glomerata grasses native to high latitudes (Kubien and Sage ). The C 4 M .…”

“…glomerata showed about 40 and 80% more net photosynthesis rate, measured at leaf temperatures of 20 and 30°C, respectively, when compared with the co‐occurring C 3 C . canadensis , both grown at warm conditions (26/22°C) (Kubien and Sage ). The difference in net assimilation rates between C 4 and C 3 plants under increasing both PPFD and leaf temperature is partly due to the difference in photorespiration between these two functional groups.…”

Chilling and frost tolerance in Miscanthus and Saccharum genotypes bred for cool temperate climates

“…In addition, even if they express cold-tolerant isoforms of C 4 cycle enzymes (as shown for Echinochloa crus-galli , for example; Simon and Hatch, 1994), cold-tolerant C 4 species may be limited by Rubisco capacity at low temperatures (Kubien and Sage, 2004 b ; Sage et al , 2011). In addition to placing a low ceiling on photosynthetic capacity, a Rubisco limitation may restrict photochemical quenching and predispose C 4 species to photoinhibition in chilly conditions (Kubien et al , 2003; Kubien and Sage, 2004 a ; Long and Spence, 2013). …”

High temperature acclimation of C4 photosynthesis is linked to changes in photosynthetic biochemistry

“…1972; Pearcy 1977; Björkman, Badger & Armond 1980). Others were mostly interested in the performance of C 4 photosynthesis at low temperature (Pietrini & Massacci 1998; Kubien & Sage 2004a,b; Naidu & Long 2004). Little or no work has been done comparing the acclimation of C 4 photosynthesis to growth temperatures which are more reflective of the variations that plants are most likely to experience within or between growing seasons.…”