Unravelling the Metabolic and Hormonal Machinery During Key Steps of Somatic Embryogenesis: A Case Study in Coffee

Rayan Awada (1, 2, 3, 4, 5) , Claudine Campa (1, 2, 3, 4, 5) , Estelle Gibault , Eveline Déchamp (1, 2, 3, 4) , Frédéric Georget (1, 2, 3, 4, 5) , Maud Lepelley , Cécile Abdallah (1, 2, 3, 4, 5) , Alexender Erban (6) , Frederico Martinez-Seidel (6) , Joachim Kopka (6) , Laurent Legendre (7) , Sophie Léran (1, 2, 3, 4, 5) , Geneviève Conejero (8, 9, 10) , Jean-Luc Verdeil (8, 9, 10) , Dominique Crouzillat , David Breton , Benoit Bertrand (1, 2, 3, 4, 5) , Hervé Etienne (1, 2, 3, 4, 5)

1 UMR IPME - UMR - Interactions Plantes Microorganismes Environnement
2 Cirad - Centre de Coopération Internationale en Recherche Agronomique pour le Développement
3 IRD [Bolivie] - Institut de Recherche pour le Développement
4 UM - Université de Montpellier
5 UMR DIADE - Diversité, adaptation, développement des plantes
6 MPI-MP - Max-Planck-Institut für Molekulare Pflanzenphysiologie
7 LEM - Laboratoire d'Ecologie Microbienne - UMR 5557
8 UMR AGAP - Amélioration génétique et adaptation des plantes méditerranéennes et tropicales
9 PHIV - Plateforme d'histocytologie et d'imagerie cellulaire végétale
10 BPMP - Biochimie et Physiologie Moléculaire des Plantes

Somatic embryogenesis (SE) is one of the most promising processes for large-scale dissemination of elite varieties. However, for many plant species, optimizing SE protocols still relies on a trial-and-error approach. Using coffee as a model plant, we report here the first global analysis of metabolome and hormone dynamics aiming to unravel mechanisms regulating cell fate and totipotency. Sampling from leaf explant dedifferentiation until embryo development covered 15 key stages. An in-depth statistical analysis performed on 104 metabolites revealed that massive re-configuration of metabolic pathways induced SE. During initial dedifferentiation, a sharp decrease in phenolic compounds and caffeine levels was also observed while auxins, cytokinins and ethylene levels were at their highest. Totipotency reached its highest expression during the callus stages when a shut-off in hormonal and metabolic pathways related to sugar and energetic substance hydrolysis was evidenced. Abscisic acid, leucine, maltotriose, myo-inositol, proline, tricarboxylic acid cycle metabolites and zeatin appeared as key metabolic markers of the embryogenic capacity. Combining metabolomics with multiphoton microscopy led to the identification of chlorogenic acids as markers of embryo redifferentiation. The present analysis shows that metabolite fingerprints are signatures of cell fate and represent a starting point for optimizing SE protocols in a rational way.

Mots clés: cell imaging; cell fate; coffee; histology; hormone content; metabolomics; somatic embryogenesis; totipotency

Mots clés: histologie; physiologie hormonale; imagerie cellulaire; cellule totipotente; embryogénèse somatique

Domaines: Biologie végétale

Rayan Awada, Claudine Campa, Estelle Gibault, Eveline Déchamp, Frédéric Georget, et al.. Unravelling the Metabolic and Hormonal Machinery During Key Steps of Somatic Embryogenesis: A Case Study in Coffee. International Journal of Molecular Sciences, 2019, 20 (19), pp.4665. ⟨10.3390/ijms20194665⟩. ⟨hal-02352508⟩