Dynamic Acclimation of Photosynthesis Increases Plant Fitness in Changing Environments      

Abstract

Plants growing in different environments develop with different photosynthetic capacities—developmental acclimation of photosynthesis. It is also possible for fully developed leaves to change their photosynthetic capacity—dynamic acclimation. The importance of acclimation has not previously been demonstrated. Here, we show that developmental and dynamic acclimation are distinct processes. Furthermore, we demonstrate that dynamic acclimation plays an important role in increasing the fitness of plants in natural environments. Plants of Arabidopsis (Arabidopsis thaliana) were grown at low light and then transferred to high light for up to 9 d. This resulted in an increase in photosynthetic capacity of approximately 40%. A microarray analysis showed that transfer to high light resulted in a substantial but transient increase in expression of a gene, At1g61800, encoding a glucose-6-phosphate/phosphate translocator GPT2. Plants where this gene was disrupted were unable to undergo dynamic acclimation. They were, however, still able to acclimate developmentally. When grown under controlled conditions, fitness, measured as seed output and germination, was identical, regardless of GPT2 expression. Under naturally variable conditions, however, fitness was substantially reduced in plants lacking the ability to acclimate. Seed production was halved in gpt2™ plants, relative to wild type, and germination of the seed produced substantially less. Dynamic acclimation of photosynthesis is thus shown to play a crucial and previously unrecognized role in determining the fitness of plants growing in changing environments.

Acclimation of metabolism to light in Arabidopsis thaliana: the glucose 6‐phosphate/phosphate translocator GPT2 directs metabolic acclimation

“…We previously demonstrated that developmental and dynamic acclimation are, to some extent, distinct processes in Arabidopsis thaliana (Athanasiou et al . 2010). …”

“…2010). Arabidopsis accession Wassilewskija‐4 (Ws‐4) shows a strong dynamic acclimation of photosynthetic capacity, increasing P max by up to 40% when moved from a low to a higher irradiance and this ability to acclimate dynamically plays a major role in determining plant's fitness in naturally fluctuating environments (Athanasiou et al .…”

“…Arabidopsis accession Wassilewskija‐4 (Ws‐4) shows a strong dynamic acclimation of photosynthetic capacity, increasing P max by up to 40% when moved from a low to a higher irradiance and this ability to acclimate dynamically plays a major role in determining plant's fitness in naturally fluctuating environments (Athanasiou et al . 2010). Regulation of acclimation to high light (HL) has been suggested to involve redox signals from electron transport, changes in carbohydrate/nutrient status and hormone levels, and requires communication between the chloroplast, cytosol and nucleus (retrograde and anterograde signalling) (Hausler et al .…”

“…We previously showed that a gene ( At1g61800 ) encoding a glucose 6‐phosphate/phosphate translocator GPT2 is required for acclimation of mature leaves to an increase in light; in a T‐DNA insertion knockout of GPT2 ( gpt2.2 ), increases in light intensity do not lead to substantial increases in P max following a fourfold increase in light from 100 to 400  μ mol m −2  s −1 (Athanasiou et al . 2010). The non‐acclimating gpt2.2 line is therefore a useful tool to study the dynamic acclimation response in Arabidopsis .…”

“…Only under variable growth conditions has a clear growth phenotype been demonstrated (Athanasiou et al . 2010). …”