Carbon-13 tracking after 13CO2 supply revealed diurnal patterns of wood formation in aspen
Plant Physiol. 2015; 168(2):478-489

Mahboubi A, Linden P, Hedenström M, Moritz T, Niittylä T

Abstract
Wood of trees is formed from carbon assimilated in the photosynthetic tissues. Determining the temporal dynamics of carbon assimilation, subsequent transport into developing wood and incorporation to cell walls would further our understanding of wood formation in particular and tree growth in general. To investigate these questions we designed a 13CO2 labelling system to study carbon transport and incorporation to developing wood of hybrid aspen (Populus tremula x tremuloides). Tracking of 13C incorporation to wood over a time course using nuclear magnetic resonance spectroscopy revealed diurnal patterns in wood cell wall biosynthesis. Dark period had a differential effect on 13C incorporation to lignin and cell wall carbohydrates. No 13C was incorporated into aromatic amino acids of cell wall proteins in the dark suggesting that cell wall protein biosynthesis ceased during the night. The results show previously unrecognised temporal patterns in wood cell wall biosynthesis, suggest diurnal cycle as a possible cue in the regulation of carbon incorporation to wood and establish a new 13C labelling method for the analysis of wood formation and secondary growth in trees.

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