Programmed Cell Death Controlled by ANAC033/SOMBRERO Determines Root Cap Organ Size in Arabidopsis

• Published in: Current biology Vol. 24; no. 9; pp. 931 - 940
• Main Authors: Fendrych, Matyáš, Van Hautegem, Tom, Van Durme, Matthias, Olvera-Carrillo, Yadira, Huysmans, Marlies, Karimi, Mansour, Lippens, Saskia, Guérin, Christopher J., Krebs, Melanie, Schumacher, Karin, Nowack, Moritz K.
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 05.05.2014
• Subjects: Arabidopsis; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Autolysis; Cell Death - genetics; Cell Proliferation; Deoxyribonucleases - genetics; Deoxyribonucleases - metabolism; DNA Fragmentation; Gene Expression Regulation, Plant; Homeostasis; Organ Size; Plant Development; Plant Root Cap - growth & development; Plant Root Cap - physiology; Transcription Factors - genetics; Transcription, Genetic
• ISSN: 0960-9822; 1879-0445; 1879-0445
• DOI: 10.1016/j.cub.2014.03.025

The root cap is a plant organ that ensheathes the meristematic stem cells at the root tip. Unlike other plant organs, the root cap shows a rapid cellular turnover, balancing constant cell generation by specific stem cells with the disposal of differentiated cells at the root cap edge. This cellular turnover is critical for the maintenance of root cap size and its position around the growing root tip, but how this is achieved and controlled in the model plant Arabidopsis thaliana remains subject to contradictory hypotheses. Here, we show that a highly organized cell death program is the final step of lateral root cap differentiation and that preparation for cell death is transcriptionally controlled by ANAC033/SOMBRERO. Precise timing of cell death is critical for the elimination of root cap cells before they fully enter the root elongation zone, which in turn is important in order to allow optimal root growth. Root cap cell death is followed by a rapid cell-autonomous corpse clearance and DNA fragmentation dependent on the S1-P1 type nuclease BFN1. Based on these results, we propose a novel concept in plant development that recognizes programmed cell death as a mechanism for maintaining organ size and tissue homeostasis in the Arabidopsis root cap. [Display omitted] •An active cell death process is integral to Arabidopsis root cap differentiation•Acquisition of cell death competency depends on ANAC033/SOMBRERO•Cell death is followed by cell-autonomous corpse cleanup involving the nuclease BFN1•Cell death controls root cap organ size and facilitates optimal root growth Fendrych et al. show that a highly organized cell death program, controlled by ANAC033/SOMBRERO, is an integral part of root cap development in Arabidopsis thaliana. This cell death program includes expression of BFN1 as preparation for cell-autonomous corpse clearance and facilitates optimal root growth by controlling root cap organ size.