Seasonal variations drive short-term dynamics and partitioning of recently assimilated carbon in the foliage of adult beech and pine

• Published in: The New phytologist Vol. 213; no. 1; pp. 140 - 153
• Main Authors: Desalme, Dorine, Priault, Pierrick, Gérant, Dominique, Dannoura, Masako, Maillard, Pascale, Plain, Caroline, Epron, Daniel
• Format: Journal Article
• Language: English
• Published: England New Phytologist Trust 01.01.2017; Wiley Subscription Services, Inc; Wiley
• Subjects: 13C pulse labelling; Carbon - metabolism; carbon allocation; Carbon Isotopes - metabolism; Fagus - metabolism; Fagus sylvatica; Kinetics; leaf carbon (C) residence time; Life Sciences; Pinus - metabolism; Pinus pinaster; Plant Leaves - metabolism; Seasons; soluble C compounds; starch; Starch - metabolism; tree phenology; Pinus pinaster; soluble C compounds; 13C pulse labelling; starch; tree phenology; carbon allocation; leaf carbon (C) residence time; Fagus sylvatica
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.14124

13CO2 pulse-labelling experiments were performed in situ on adult beeches (Fagus sylvatica) and pines (Pinus pinaster) at different phenological stages to study seasonal and interspecific short-term dynamics and partitioning of recently assimilated carbon (C) in leaves. Polar fraction (PF, including soluble sugars, amino acids and organic acids) and starch were purified from foliage sampled during a 10-d chase period. C contents, isotopic compositions and 13C dynamics parameters were determined in bulk foliage, PF and starch. Decrease in 13C amount in bulk foliage followed a two-pool exponential model highlighting 13C partitioning between ‘mobile’ and ‘stable’ pools, the relative proportion of the latter being maximal in beech leaves in May. Early in the growing season, new foliage acted as a strong C sink in both species, but although young leaves and needles were already photosynthesizing, the latter were still supplied with previous-year needle photosynthates 2 months after budburst. Mean 13C residence times (MRT) were minimal in summer, indicating fast photosynthate export to supply perennial organ growth in both species. In late summer, MRT differed between senescing beech leaves and overwintering pine needles. Seasonal variations of 13C partitioning and dynamics in field-grown tree foliage are closely linked to phenological differences between deciduous and evergreen trees.