Dr Virginie Mengin

Dr Virginie Mengin is working in Christine Raines’ research group at the University of Essex on the Capitalise project. She used to work in Mark Stitt’s group at the Max Planck Institute of Molecular Plant Physiology where she gained knowledge about central carbon metabolism, plant physiology, light signalling, and chronobiology. She is now focusing on engineering plants with altered expression of enzymes and proteins involved in the Calvin-Benson-Bassham cycle and following selected metabolite changes within crop natural accessions grown in artificial or natural conditions.

Title: Tuning the Calvin Benson Bassham cycle in selected crops

Webinar date: Tuesday 5th April 2022  14.00 CET

Abstract: In seed crops grown under optimal conditions, the energy conversion efficiency (which is determined by overall canopy photosynthesis minus respiration) is far from its maximum potential level and makes photosynthesis an important target for improvement to raise yield potential.

In the Calvin-Benson (CB) cycle, CO2 assimilation rates in steady state are typically limited by carboxylation capacity of the cycle (determined by Rubisco activity) or by the capacity for regeneration of carboxylation reaction substrate, ribulose 1,5 bisphosphate (RuBP). Detailed models of C3 photosynthetic carbon metabolism predicted a strong limitation of photosynthesis by sedoheptulose-1,7-bisphosphatase (SBPase) and, to a lesser extent, fructose-1,6-bishphosphate aldolase (FBPA). Previous work from the Raine’s lab indicated that, consistent with these predictions, transgenic overexpression of SBPase and FBPA improved photosynthesis and growth in the model species Arabidopsis and in tobacco. These results are highly significant as they provide direct evidence that there is potential to take a biotechnological approach to increase yield by improving RuBP regeneration.

In the context of the CAPITALISE project, we are aiming to re-tune the CB cycle in target crops, i.e., tomato and barley. For that we are looking at improving transcriptional rates of key CBB enzymes (i.e., SBPase, FBPA, and Rubisco Activase). Because current European regulations forbid the usage of traditional genetically modified organism for agriculture, we decided to investigate the cis-regulatory modules (CRMs) around our genes of interest to find potential repressors of expression (silencers) that could be later edited out using CRISPR-Cas methods. We are using a combination of shotgun and targeted approaches to identify these motifs and test them using YFP reporter in transient assays before testing in planta for improved transcription rate, enzymatic activity, photosynthesis, and yield.