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Synthetic conversion of leaf chloroplasts into carotenoid-rich plastids reveals mechanistic basis of natural chromoplast development.

Briardo LlorenteSalvador Torres-MontillaLuca MorelliIgor Florez-SarasaJosé Tomás MatusMiguel EzquerroLucio D'AndreaFakhreddine HouhouEszter MajerBelén PicóJaime Cebolla-CornejoAdrian TroncosoAlisdair Robert FernieJosé-Antonio DaròsManuel Rodriguez-Concepcion
Published in: Proceedings of the National Academy of Sciences of the United States of America (2020)
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 (provitamin 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, a process that involves a concurrent reprogramming of nuclear gene expression and plastid morphology for improved carotenoid storage. We hence demonstrate that loss of photosynthetic competence and enhanced production of carotenoids are not just consequences but requirements for chloroplasts to differentiate into chromoplasts.
Keyphrases
  • gene expression
  • induced apoptosis
  • dna methylation
  • arabidopsis thaliana
  • cell cycle arrest
  • wastewater treatment
  • oxidative stress
  • risk assessment
  • radiation therapy
  • endoplasmic reticulum stress
  • cell wall