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Divergence in δ 13 C of dark respired CO 2 and bulk organic matter occurs during the transition between heterotrophy and autotrophy in Phaseolus vulgaris plants
Author(s) -
Bathellier Camille,
Badeck FranzW.,
Couzi Philippe,
Harscoët Sébastien,
Mauve Caroline,
Ghashghaie Jaleh
Publication year - 2008
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2007.02246.x
Subject(s) - phaseolus , autotroph , organic matter , heterotroph , botany , chemistry , divergence (linguistics) , environmental chemistry , biology , ecology , bacteria , paleontology , linguistics , philosophy
Summary• Substantial evidence has been published in recent years demonstrating that postphotosynthetic fractionations occur in plants, leading to 13 C‐enrichment in heterotrophic (as compared with autotrophic) organs. However, less is known about the mechanism responsible for changes in these responses during plant development. • The isotopic signature of both organic matter and respired CO 2 for different organs of French bean ( Phaseolus vulgaris ) was investigated during early ontogeny, in order to identify the developmental stage at which isotopic changes occur. Isotopic analyses of metabolites and mass balance calculations helped to constrain the metabolic processes involved. • At the plant scale, apparent respiratory fractionation was constantly positive in the heterotrophic phase ( c . 1‰) and turned negative with autotrophy acquisition (down to –3.08‰). Initially very close to that of the dry seed (–26.83 ± 0.69‰), isotopic signatures of organic matter and respired CO 2 diverged (in opposite directions) in leaves and roots after onset of photosynthesis. Respired CO 2 reached values up to –20‰ in leaves and became 13 C‐depleted down to –29‰ in roots. • It was concluded that isotopic differences between organs occurred subsequent to metabolic changes in the seedling during the transition from heterotrophy to autotrophy. They were especially related to respiration and respiratory fractionation.