Mutation of MEDIATOR 18 and chromate trigger twinning of the primary root meristem in Arabidopsis

• Published in: Plant, cell and environment Vol. 43; no. 8; pp. 1989 - 1999
• Main Authors: Ruiz‐Aguilar, Bricia, Raya‐González, Javier, López‐Bucio, Jesús Salvador, Reyes de la Cruz, Homero, Herrera‐Estrella, Luis, Ruiz‐Herrera, León Francisco, Martínez‐Trujillo, Miguel, López‐Bucio, José
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-08-2020; Wiley Subscription Services, Inc
• Subjects: Antibiotics; Arabidopsis; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; auxin; Cell activation; Chromate; Chromates; Chromium; Chromium - pharmacology; Gene Expression Regulation, Plant; Genotoxic chemicals; Genotoxicity; Homeodomain Proteins - genetics; Indoleacetic Acids - metabolism; Mediator complex; Mediator Complex - genetics; Mediator Complex - metabolism; Meristem - drug effects; Meristem - genetics; Meristems; Mutation; Plant Roots - drug effects; Plant Roots - genetics; Plant Roots - growth & development; Plants, Genetically Modified; Pollutants; Regeneration; Replenishment; Roots; Soil stresses; Splitting; Stem cells; Transcription; Transcription Factors - genetics; Ultraviolet radiation; stem cells; Mediator complex; chromate; auxin; regeneration
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/pce.13786

Plants adapt to soil injury and biotic stress via cell regeneration. In Arabidopsis, root tip damage by genotoxic agents, antibiotics, UV light and cutting induces a program that recovers the missing tissues through activation of stem cells and involves ethylene response factor 115 (ERF115), which triggers cell replenishment. Here, we show that mutation of the gene encoding an MED18 subunit of the transcriptional MEDIATOR complex and chromate [Cr(VI)], an environmental pollutant, synergistically trigger a developmental program that enables the splitting of the meristem in vivo to produce twin roots. Expression of the quiescent centre gene marker WOX5, auxin‐inducible DR5:GFP reporter and the ERF115 factor traced the changes in cell identity during the conversion of single primary root meristems into twin roots and were induced in an MED18 and chromate‐dependent manner during the root twinning events, which also required auxin redistribution and signalling mediated by IAA14/SOLITARY ROOT (SLR1). Splitting of the root meristem allowed dichotomous root branching in Arabidopsis, a poorly understood process in which stem cells may act to enable whole organ regeneration.
This manuscript describes the twinning of the primary root meristem, also termed root fasciation, in Arabidopsis med18 mutants treated with chromate. Root regeneration takes place through cell re‐specification programs, which correlates with quiescent centre, auxin re‐distribution and cell renewal.