δ13C of bulk organic matter and cellulose reveal post-photosynthetic fractionation during ontogeny in C4 grass leaves

Yong Zhi Yu, Hai Tao Liu, Fang Yang, Lei Li, Rudi Schäufele, Guillaume Tcherkez, Hans Schnyder, Xiao Ying Gong

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The 13C isotope composition (δ13C) of leaf dry matter is a useful tool for physiological and ecological studies. However, how post-photosynthetic fractionation associated with respiration and carbon export influences δ13C remains uncertain. We investigated the effects of post-photosynthetic fractionation on δ13C of mature leaves of Cleistogenes squarrosa, a perennial C4 grass, in controlled experiments with different levels of vapour pressure deficit and nitrogen supply. With increasing leaf age class, the 12C/13C fractionation of leaf organic matter relative to the δ13C of atmosphere CO2DM) increased while that of cellulose (Δcel) was almost constant. The divergence between ΔDM and Δcel increased with leaf age class, with a maximum value of 1.60/100, indicating the accumulation of post-photosynthetic fractionation. Applying a new mass balance model that accounts for respiration and export of photosynthates, we found an apparent 12C/13C fractionation associated with carbon export of –0.50/100 to –1.00/100. Different ΔDM among leaves, pseudostems, daughter tillers, and roots indicate that post-photosynthetic fractionation happens at the whole-plant level. Compared with ΔDM of old leaves, ΔDM of young leaves and Δcel are more reliable proxies for predicting physiological parameters due to the lower sensitivity to post-photosynthetic fractionation and the similar sensitivity in responses to environmental changes.

Original languageEnglish
Pages (from-to)1451-1464
Number of pages14
JournalJournal of Experimental Botany
Volume75
Issue number5
DOIs
StatePublished - 28 Feb 2024
Externally publishedYes

Keywords

  • C plants
  • Carbon export
  • cellulose
  • photosynthesis
  • post-photosynthetic fractionation
  • respiration
  • sink–source relation
  • water use efficiency

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