In short photoperiods plants accumulate starch more rapidly in the light and degrade it more slowly at night, ensuring that their starch reserves last until dawn. To investigate the accompanying changes in the timing of growth, Arabidopsis was grown in a range of photoperiods and analysed for rosette biomass, photosynthesis, respiration, ribosome abundance, polysome loading, starch, and over 40 metabolites at dawn and dusk. The dataset was used to model growth rates in the daytime and night, and to identify metabolites that correlate with growth. Modelled growth rates and polysome loading were high in the daytime and at night in long photoperiods, but decreased at night in short photoperiods. Ribosome abundance was similar in all photoperiods. It is discussed how the amount of starch accumulated in the light period, the length of the night and maintenance costs interact to constrain growth at night in short photoperiods, and alter the strategy for optimising ribosome use. Significant correlations were found in the daytime and the night between growth rates and the levels of the sugar-signal trehalose 6-phosphate and the amino acid biosynthesis intermediate shikimate, identifying these metabolites as hubs in a network that coordinates growth with diurnal changes in the carbon supply.
Ronan Sulpice, Anna Flis, Alexander A. Ivakov, Federico Apelt, Nicole Krohn, Beatrice Encke, Christin Abel, Regina Feil, John E. Lunn, and Mark Stitt
Mol. Plant (2013) http://dx.doi.org/10.1093/mp/sst127