# Why leaves become isotopically lighter than photosynthetic carbon isotope discrimination explains: on the importance of post-photosynthetic fractionation

## TL;DR

This paper explains why leaf carbon isotope values are lighter than expected, highlighting the role of post-photosynthetic fractionation in C4 grasses.

## Contribution

It identifies post-photosynthetic fractionation as a key factor affecting carbon isotope composition in C4 grass leaves during development.

## Key findings

- Carbon isotope values in C4 grass leaves become lighter than predicted by photosynthetic discrimination.
- Post-photosynthetic fractionation occurs during leaf ontogeny, affecting bulk organic matter and cellulose.
- This fractionation is significant and must be considered in carbon isotope studies of C4 plants.

## Abstract

This article comments on:

Yu YZ, Liu HT, Yang F, Li L, Schäufele R, Tcherkez G, Schnyder H, Gong XY. 2024. δ13C of bulk organic matter and cellulose reveal post-photosynthetic fractionation during ontogeny in C4 grass leaves. Journal of Experimental Botany 75, 1451–1464