Metabolic profiling reveals metabolic shifts in Arabidopsis plants grown under different light conditions

ABSTRACT Plants have tremendous capacity to adjust their morphology, physiology and metabolism in response to changes in growing conditions. Thus, analysis solely of plants grown under constant conditions may give partial or misleading indications of their responses to the fluctuating natural conditions in which they evolved. To obtain data on growth condition‐dependent differences in metabolite levels, we compared leaf metabolite profiles of Arabidopsis thaliana growing under three constant laboratory light conditions: 30 [low light (LL)], 300 [normal light (NL)] and 600 [high light (HL)]µmol photons m−2 s−1. We also shifted plants to the field and followed their metabolite composition for 3 d. Numerous compounds showed light intensity‐dependent accumulation, including: many sugars and sugar derivatives (fructose, sucrose, glucose, galactose and raffinose); tricarboxylic acid (TCA) cycle intermediates; and amino acids (ca. 30% of which were more abundant under HL and 60% under LL). However, the patterns differed after shifting NL plants to field conditions. Levels of most identified metabolites (mainly amino acids, sugars and TCA cycle intermediates) rose after 2 h and peaked after 73 h, indicative of a ‘biphasic response’ and ‘circadian’ effects. The results provide new insight into metabolomic level mechanisms of plant acclimation, and highlight the role of known protectants under natural conditions. Plants have tremendous capacity to acclimate to environmental condition. Therefore, analysis solely of plants grown under constant conditions may give partial or misleading indications of their responses to the fluctuating natural conditions in which they evolved. Metabolic profiling offers a powerful way to understand the metabolic changes at global level in plants under ambient and stressful condition and we have studied systematic differences in metabolite levels between Arabidopsis thaliana grown under field and controlled conditions. Numerous compounds showed light‐intensity dependent accumulation under controlled conditions, including many sugars and sugar derivatives. When plants were shifted to field conditions, levels of many identified metabolites (mainly amino acids, sugars and TCA cycle intermediates) rose after 2 h and peaked after 73 h, indicative of a ‘biphasic response’ and ‘circadian’ effects