MEDIATOR18 influences Arabidopsis root architecture, represses auxin signaling and is a critical factor for cell viability in root meristems

Javier Raya-González, Araceli Oropeza-Aburto, Jesús S. López-Bucio, Ángel A. Guevara-García, Lieven de Veylder, José López-Bucio, Luis Herrera-Estrella

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The Mediator (MED) complex plays a key role in the recruitment and assembly of the transcription machinery for the control of gene expression. Here, we report on the role of MEDIATOR18 (MED18) subunit in root development, auxin signaling and meristem cell viability in Arabidopsis thaliana seedlings. Loss-of-function mutations in MED18 reduce primary root growth, but increase lateral root formation and root hair development. This phenotype correlates with alterations in cell division and elongation likely caused by an increased auxin response and transport at the root tip, as evidenced by DR5:GFP, pPIN1::PIN1-GFP, pPIN2::PIN2-GFP and pPIN3::PIN3-GFP auxin-related gene expression. Noteworthy, med18 seedlings manifest cell death in the root meristem, which exacerbates with age and/or exposition to DNA-damaging agents, and display high expression of the cell regeneration factor ERF115. Cell death in the root tip was reduced in med18 seedlings grown in darkness, but remained when only the shoot was exposed to light, suggesting that MED18 acts to protect root meristem cells from local cell death, and/or in response to root-acting signal(s) emitted by the shoot in response to light stimuli. These data point to MED18 as an important component for auxin-regulated root development, cell death and cell regeneration in root meristems.

Original languageEnglish
Pages (from-to)895-909
Number of pages15
JournalPlant Journal
Volume96
Issue number5
DOIs
StatePublished - Dec 2018

Keywords

  • Arabidopsis thaliana
  • auxin signaling
  • cell death
  • regeneration
  • root development

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