J Exp Bot.: auth.: group Fankhauser

J Exp Bot. 2021 Feb 5;erab038. doi: 10.1093/jxb/erab038. Online ahead of print.

Phytochromes control metabolic flux, and their action at the seedling stage determines adult plant biomass

Johanna Krahmer 1 2Ammad Abbas 1Virginie Mengin 3Hirofumi Ishihara 3Andrés Romanowski 1James J Furniss 1 4Thiago Alexandre Moraes 3Nicole Krohn 3Maria Grazia Annunziata 3Regina Feil 3Saleh Alseekh 3Toshihiro Obata 3 5Alisdair R Fernie 3Mark Stitt 3Karen J Halliday 1Affiliations expand


Phytochrome (phy) photoreceptors are known to regulate plastic growth responses to vegetation shade. However, recent reports also suggest an important role for phys in carbon resource management, metabolism, and growth. Here, we use 13CO2 labelling patterns in multi-allele phy mutants to investigate the role of phy in the control of metabolic fluxes. We also combine quantitative data of 13C incorporation into protein and cell wall polymers, gas exchange measurements and system modelling to investigate why biomass is decreased in adult multi-allele phy mutants. Phy influences the synthesis of stress metabolites like raffinose and proline, and the accumulation of sugars, possibly through regulating vacuolar sugar transport. Remarkably, despite their modified metabolism and vastly altered architecture, growth rates in adult phy mutants resemble those of wild-type plants. Our results point to delayed seedling growth and smaller cotyledon size as the cause of the adult-stage phy mutant biomass defect. Our data signify a role for phy in metabolic stress physiology, carbon partitioning and illustrate that phy action at the seedling stage sets the trajectory for adult biomass production.

Keywords: 13C labelling; growth modelling; metabolic flux; phytochrome; plant growth; stress metabolites.