Authors: B. LlorenteS. Torres-MontillaL. MorelliI. Florez SarasaM. EzquerroL. D’andreaE. MajerA. TroncosoA. R. FernieJ. A. DaròsM. Rodriguez Concepcion

Institutions:

  • Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, 08193 Barcelona, Spain
  • ARC Center of Excellence in Synthetic Biology, Department of Molecular Sciences, Macquarie University, Sydney NSW 2109, Australia
  • CSIRO Synthetic Biology Future Science Platform, Sydney NSW 2109, Australia
  • Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas-Universitat Politècnica de València, 46022 Valencia, Spain
  • Sorbonne Universités, Université de Technologie de Compiègne, Génie Enzymatique et Cellulaire (GEC), UMR-CNRS 7025, CS 60319, 60203 Compiègne Cedex, France
  • Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476 Potsdam-Golm, Germany
  • Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain

Publication: biorxiv.org

Date: October 2019

Full paper: https://www.biorxiv.org/content/10.1101/819177v1.full

Abstract:
Plastids, the defining organelles of plant cells, undergo physiological and morphological changes to fulfill distinct biological functions. In particular, the differentiation of chloroplasts into chromoplasts results in an enhanced storage capacity for carotenoids with industrial and nutritional value such as beta-carotene (pro-vitamin A). Here, we show that synthetically inducing a burst in the production of phytoene, the first committed intermediate of the carotenoid pathway, elicits an artificial chloroplast-to-chromoplast differentiation in leaves. Phytoene overproduction initially interferes with photosynthesis, acting as a metabolic threshold switch mechanism that weakens chloroplast identity. In a second stage, phytoene conversion into downstream carotenoids is required for the differentiation of chromoplasts. Our findings reveal that lowering the photosynthetic capacity of chloroplasts and increasing the production of carotenoids are not just the consequence but an absolute requirement for chromoplast differentiation, which additionally involves a concurrent reprogramming of nuclear gene expression and plastid morphology for improved carotenoid storage.