Abstract
Intense efforts have been devoted to describe the biochemical pathway of plant sulphur (S) assimilation from sulphate. However, essential information on metabolic regulation of S assimilation is still lacking, such as possible interactions between S assimilation, photosynthesis and photorespiration. In particular, does S assimilation scale with photosynthesis thus ensuring sufficient S provision for amino acids synthesis? This lack of knowledge is problematic because optimization of photosynthesis is a common target of crop breeding and furthermore, photosynthesis is stimulated by the inexorable increase in atmospheric CO2. Here, we used high-resolution 33S and 13C tracing technology with NMR and LC-MS to access direct measurement of metabolic fluxes in S assimilation, when photosynthesis and photorespiration are varied via the gaseous composition of the atmosphere (CO2, O2). We show that S assimilation is stimulated by photorespiratory metabolism and therefore, large photosynthetic fluxes appear to be detrimental to plant cell sulphur nutrition.
Highlights
Intense efforts have been devoted to describe the biochemical pathway of plant sulphur (S) assimilation from sulphate
We found that leaf cysteine inherited carbon atoms derived from photosynthesis as shown by the clear 13C-enrichment regardless of gas-exchange conditions, including at low photorespiration (Fig. 2a)
LCMS analyses with fragmentation showed that the intramolecular isotopic distribution was highly heterogeneous, with a strong 13C enrichment in the methyl group and very little 13C in other C-atoms (Fig. 2a, Supplementary Fig. 1). Such a pattern suggests a higher turnover of the methyl group and is typical of photorespiration, which leads to the production of highly 13C-enriched glycine, serine and one-carbon units
Summary
Intense efforts have been devoted to describe the biochemical pathway of plant sulphur (S) assimilation from sulphate. Essential information on metabolic regulation of S assimilation is still lacking, such as possible interactions between S assimilation, photosynthesis and photorespiration. We show that S assimilation is stimulated by photorespiratory metabolism and large photosynthetic fluxes appear to be detrimental to plant cell sulphur nutrition. The relationship with photosynthesis has never been tested experimentally and it is presently uncertain as to whether S assimilation can be impacted by environmental conditions that affect photosynthetic metabolism. The question of a possible correlation between photosynthesis and S assimilation in the short term is important since in the field, photosynthesis can vary considerably depending on environmental conditions, and plant S nutrition could be affected . Changes in S metabolism when photosynthesis varies could stem from metabolic interactions with photorespiration
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
