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Article Dans Une Revue Current Biology - CB Année : 2015

OCTOPUS Negatively Regulates BIN2 to Control Phloem Differentiation in Arabidopsis thaliana

Pauline Anne
  • Fonction : Auteur
  • PersonId : 775057
  • IdRef : 183373561
Marianne Azzopardi
  • Fonction : Auteur
  • PersonId : 956914
Lionel Gissot
  • Fonction : Auteur
  • PersonId : 1204825
Sébastien Beaubiat
  • Fonction : Auteur
  • PersonId : 1010187
Kian Hematy

Résumé

The phloem is a vascular strand that conducts photo-assimilates and systemic signals throughout the plant to coordinate growth. To date, few molecular genetic determinants have been identified to control both specification and differentiation of this tissue [1-3]. Among them, OCTOPUS (OPS) protein was previously identified as a polarly localized plasma membrane-associated protein of unknown biochemical function whose broad provascular expression becomes restricted to the phloem upon differentiation [2]. OPS loss-of-function mutants showed an altered vascular network in cotyledons and an intermittent phloem differentiation in the root [2, 4]. Here, we demonstrate a role for OPS as a positive regulator of the brassinosteroid (BR) signaling pathway. Indeed, transgenic lines overexpressing OPS (OPS-OE) display the hallmarks of constitutively overactivated BR mutants. Physiological and genetic analyses place OPS as a positive regulator of the BR signaling pathway upstream of the key transcription factors BES1 and BZR1. Directed protein interactions with known BR signaling proteins identified BIN2, a GSK3 protein involved in multiple signaling pathways, as a partner of OPS. This interaction recruits BIN2 to the plasma membrane, thus preventing its inhibitory activity in the nucleus. Finally, both bikinin (a potent inhibitor of GSK3 [5]) treatment and downstream dominant mutants bes1-D [6] and bzr1-D [7] can rescue phloem defects of ops in the root. Together, our data show that OPS antagonizes BIN2 to promote phloem differentiation.

Dates et versions

hal-01536504 , version 1 (11-06-2017)

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Citer

Pauline Anne, Marianne Azzopardi, Lionel Gissot, Sébastien Beaubiat, Kian Hematy, et al.. OCTOPUS Negatively Regulates BIN2 to Control Phloem Differentiation in Arabidopsis thaliana. Current Biology - CB, 2015, 25 (19), pp.2584 - 2590. ⟨10.1016/j.cub.2015.08.033⟩. ⟨hal-01536504⟩
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