A CCaMK/Cyclops response element in the promoter of Lotus japonicus calcium-binding protein 1 (CBP1) mediates transcriptional activation in root symbioses

Xiaoyun Gong, Elaine Jensen, Simone Bucerius, Martin Parniske*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)
123 Downloads (Pure)

Abstract

Early gene expression in arbuscular mycorrhiza (AM) and the nitrogen-fixing root nodule symbiosis (RNS) is governed by a shared regulatory complex. Yet many symbiosis-induced genes are specifically activated in only one of the two symbioses.
The Lotus japonicus T-DNA insertion line T90, carrying a promoterless uidA (GUS) gene in the promoter of Calcium Binding Protein 1 (CBP1) is exceptional as it exhibits GUS activity in both root endosymbioses. To identify the responsible cis- and trans-acting factors, we subjected deletion/modification series of CBP1 promoter : reporter fusions to transactivation and spatio-temporal expression analysis and screened ethyl methanesulphonate (EMS)-mutagenized T90 populations for aberrant GUS expression.
We identified one cis-regulatory element required for GUS expression in the epidermis and a second element, necessary and sufficient for transactivation by the calcium and calmodulin-dependent protein kinase (CCaMK) in combination with the transcription factor Cyclops and conferring gene expression during both AM and RNS. Lack of GUS expression in T90 white mutants could be traced to DNA hypermethylation detected in and around this element.
We concluded that the CCaMK/Cyclops complex can contribute to at least three distinct gene expression patterns on its direct target promoters NIN (RNS), RAM1 (AM), and CBP1 (AM and RNS), calling for yet-to-be identified specificity-conferring factors.
Original languageEnglish
Pages (from-to)1196-1211
Number of pages16
JournalNew Phytologist
Volume235
Issue number3
Early online date29 May 2022
DOIs
Publication statusPublished - 30 Jun 2022

Keywords

  • arbuscular mycorrhizal (AM) symbiosis
  • DNA methylation
  • epigenetic modification
  • ethyl methanesulphonate (EMS) mutagenesis
  • nitrogen-fixing root nodule symbiosis
  • T-DNA insertion
  • tissue specificity
  • transcriptional regulation
  • Plant Proteins/metabolism
  • Response Elements
  • Symbiosis/genetics
  • Lotus/metabolism
  • Minocycline/metabolism
  • Mycorrhizae/physiology
  • Calcium-Binding Proteins/metabolism
  • Transcriptional Activation/genetics
  • Gene Expression Regulation, Plant

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