Interaction of temperature and irradiance effects on photosynthetic acclimation in two accessions of Arabidopsis thaliana

Thijs L Pons

doi:10.1007/s11120-012-9756-3

Abstract

The effect of temperature and irradiance during growth on photosynthetic traits of two accessions of Arabidopsis thaliana was investigated. Plants were grown at 10 and 22 °C, and at 50 and 300 μmol photons m−2 s−1 in a factorial design. As known from other cold-tolerant herbaceous species, growth of Arabidopsis at low temperature resulted in increases in photosynthetic capacity per unit leaf area and chlorophyll. Growth at high irradiance had a similar effect. However, the growth temperature and irradiance showed interacting effects for several capacity-related variables. Temperature effects on the ratio between electron transport capacity and carboxylation capacity were also different in low compared to high irradiance grown Arabidopsis. The carboxylation capacity per unit Rubisco, a measure for the in vivo Rubisco activity, was low in low irradiance grown plants but there was no clear growth temperature effect. The limitation of photosynthesis by the utilization of triose-phosphate in high temperature grown plants was less when grown at low compared to high irradiance. Several of these traits contribute to reduced efficiency of the utilization of resources for photosynthesis of Arabidopsis at low irradiance. The two accessions from contrasting climates showed remarkably similar capabilities of developmental acclimation to the two environmental factors. Hence, no evidence was found for photosynthetic adaptation of the photosynthetic apparatus to specific climatic conditions.

Highlights

Photosynthetic acclimation to different levels of growth irradiance has been studied extensively (Boardman 1977; Anderson et al 1995; Walters 2005)
Reduced growth irradiance typically causes a reduction in the amount of Rubisco, other Calvin cycle enzymes and components of the electron transport chain, all expressed per unit leaf area
The change in the balance is achieved by an increase in light harvesting complex (LHC) relative to core chlorophyll, which is reflected in a lower chlorophyll a/b ratio (Anderson et al 1995; Hikosaka and Terashima 1995)

Summary

Introduction

Photosynthetic acclimation to different levels of growth irradiance has been studied extensively (Boardman 1977; Anderson et al 1995; Walters 2005). Chlorophyll content remains generally rather constant (Hikosaka and Terashima 1996), causing a change in the balance between light harvesting and photosynthetic capacity in favor of the former. The change in the balance is achieved by an increase in light harvesting complex (LHC) relative to core chlorophyll, which is reflected in a lower chlorophyll a/b ratio (Anderson et al 1995; Hikosaka and Terashima 1995). The reduced amount of photosynthetic proteins per area in shade requires a lower number of chloroplasts. This in turn requires less space in mesophyll cells (Terashima et al 2011), which makes the shade-grown leaf thinner. Shade leaves have reduced costs per area in terms of nitrogen (Pons and Anten 2004) and of carbon as the leaf dry mass per area (LMA) is lower (Poorter et al 2009)

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