Importance of Fluctuations in Light on Plant Photosynthetic Acclimation.

Silvere Vialet-Chabrand,Andrew J Simkin,Christine A Raines,Jack S A Matthews,Tracy Lawson

doi:10.1104/pp.16.01767

Abstract

The acclimation of plants to light has been studied extensively, yet little is known about the effect of dynamic fluctuations in light on plant phenotype and acclimatory responses. We mimicked natural fluctuations in light over a diurnal period to examine the effect on the photosynthetic processes and growth of Arabidopsis (Arabidopsis thaliana). High and low light intensities, delivered via a realistic dynamic fluctuating or square wave pattern, were used to grow and assess plants. Plants subjected to square wave light had thicker leaves and greater photosynthetic capacity compared with fluctuating light-grown plants. This, together with elevated levels of proteins associated with electron transport, indicates greater investment in leaf structural components and photosynthetic processes. In contrast, plants grown under fluctuating light had thinner leaves, lower leaf light absorption, but maintained similar photosynthetic rates per unit leaf area to square wave-grown plants. Despite high light use efficiency, plants grown under fluctuating light had a slow growth rate early in development, likely due to the fact that plants grown under fluctuating conditions were not able to fully utilize the light energy absorbed for carbon fixation. Diurnal leaf-level measurements revealed a negative feedback control of photosynthesis, resulting in a decrease in total diurnal carbon assimilated of at least 20%. These findings highlight that growing plants under square wave growth conditions ultimately fails to predict plant performance under realistic light regimes and stress the importance of considering fluctuations in incident light in future experiments that aim to infer plant productivity under natural conditions in the field.

Highlights

The acclimation of plants to light has been studied extensively, yet little is known about the effect of dynamic fluctuations in light on plant phenotype and acclimatory responses
Külheim et al (2002) compared field-grown nonphotochemical quenching (NPQ) Arabidopsis (Arabidopsis thaliana) mutants with those grown in controlled environment chambers under constant or variable light intensity and demonstrated that NPQ is important for plant fitness in the field and under fluctuating environments reproduced in growth chambers
There was significantly greater a mass integrated (Amass) in plants grown under fluctuating light regimes compared with those grown under square wave light regimes (Fig. 2B) and, as expected, a tendency for plants grown under high-light regimes to have greater rates of Amass compared with plants grown under low-light regimes

Summary

Introduction

The acclimation of plants to light has been studied extensively, yet little is known about the effect of dynamic fluctuations in light on plant phenotype and acclimatory responses. Diurnal leaf-level measurements revealed a negative feedback control of photosynthesis, resulting in a decrease in total diurnal carbon assimilated of at least 20% These findings highlight that growing plants under square wave growth conditions fails to predict plant performance under realistic light regimes and stress the importance of considering fluctuations in incident light in future experiments that aim to infer plant productivity under natural conditions in the field. The ability of plants to developmentally acclimate to a given light environment is well demonstrated in leaves grown in sun and shade conditions, which differ in photosynthetic efficiency, biochemistry (e.g. Rubisco content and change in PSII and PSI ratio), anatomy (e.g. chloroplast size and distribution), and morphology (e.g. leaf mass area and thickness; Givnish, 1988; Walters and Horton, 1994; Weston et al, 2000; Bailey et al, 2001, 2004). The study by Külheim et al (2002) was one of the first to examine the influence of dynamic and square wave growth light regimes on plant performance and growth, the dynamic light regime used in the controlled environment did not mimic that observed in the field

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Discussion

Conclusion