The dual role of LESION SIMULATING DISEASE 1 as a condition-dependent scaffold protein and transcription regulator.

Weronika Czarnocka,Patrick Willems,Anna Rusaczonek,Bernd Mueller‐Roeber,Magdalena Szechyńska‐Hebda,Frank Van Breusegem,Stanisław Karpiński,Katrien Van Der Kelen,Salma Balazadeh,Sara Shahnejat‐Bushehri

doi:10.1111/pce.12994

Abstract

Since its discovery over two decades ago as an important cell death regulator in Arabidopsis thaliana, the role of LESION SIMULATING DISEASE 1 (LSD1) has been studied intensively within both biotic and abiotic stress responses as well as with respect to plant fitness regulation. However, its molecular mode of action remains enigmatic. Here, we demonstrate that nucleo-cytoplasmic LSD1 interacts with a broad range of other proteins that are engaged in various molecular pathways such as ubiquitination, methylation, cell cycle control, gametogenesis, embryo development and cell wall formation. The interaction of LSD1 with these partners is dependent on redox status, as oxidative stress significantly changes the quantity and types of LSD1-formed complexes. Furthermore, we show that LSD1 regulates the number and size of leaf mesophyll cells and affects plant vegetative growth. Importantly, we also reveal that in addition to its function as a scaffold protein, LSD1 acts as a transcriptional regulator. Taken together, our results demonstrate that LSD1 plays a dual role within the cell by acting as a condition-dependent scaffold protein and as a transcription regulator.

Highlights

Because of their sessile nature, plants growing in a natural environment are continuously exposed to a broad range of both biotic and abiotic stresses
In order to evaluate the subcellular localization of LESION SIMULATING DISEASE 1 (LSD1), we fused it with green fluorescent protein (GFP) under the control of the endogenous (LSD1pro) or constitutive cauliflower mosaic virus 35S (CaMV 35S) promoter (35Spro)
Our results indicating that LSD1 interacts with proteins involved in cell cycle and cell wall formation as well as controls the

Summary

Introduction

Because of their sessile nature, plants growing in a natural environment are continuously exposed to a broad range of both biotic and abiotic stresses. Cell death is an organized process of the cells' self-elimination It plays a crucial role in plant development (Fukuda 2000; Domínguez & Cejudo 2014), immune defence (Jabs, Dietrich, & Dangl 1996) and acclimatory responses (Mühlenbock et al 2007). In this context, CD is the ultimate end of the cell life cycle and maintains cell homeostasis in various plant organs and tissues during unfavourable environmental conditions. While the molecular mechanisms of CD are rather well documented in animal systems, the molecular processes underlying plant CD remain largely enigmatic

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