Far-red perception by vegetative organs and not fruits drives fruit growth responses in tomato plants

Although fruit-localised phytochromes can influence starch and sugar metabolism, their involvement in modulating fruit growth responses to far-red is unknown. We explored whether fruit growth responses to far-red are driven by local far-red perception within the fruits, or by a systemic response initiated in the vegetative organs.

We applied far-red exclusively to the fruiting trusses, from anthesis to ripening, to the vegetative organs, to both, or to neither. We quantified plant development and fruit growth responses to far-red and carried out a transcriptomic analysis to establish the temporal dynamics of far-red perception and signalling in leaves and fruits. Supplementing far-red to the vegetative organs led to a significant increase in ripe fruit weight and sugar concentration, regardless of the light conditions experienced by the trusses, whereas far-red supplementation to the generative organs alone had no measurable effect.