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Regulated cell death (RCD) is crucial for plant development, as well as in decision-making in plant-microbe interactions. Previous studies revealed components of the molecular network controlling RCD, including different proteases. However, the identity, the proteolytic network as well as molecular components involved in the initiation and execution of distinct plant RCD processes, still remain largely elusive. In this study, we analyzed the transcriptome, proteome, and N-terminome of Zea mays leaves treated with the Xanthomonas effector avrRxo1, the mycotoxin Fumonisin B1 (FB1), or the phytohormone salicylic acid (SA) to dissect plant cellular processes related to cell death and plant immunity. We found highly distinct and time-dependent biological processes being activated on transcriptional and proteome levels in response to avrRxo1, FB1, and SA. Correlation analysis of the transcriptome and proteome identified general, as well as trigger-specific markers for cell death in Zea mays. We found that proteases, particularly papain-like cysteine proteases, are specifically regulated during RCD. Collectively, this study characterizes distinct RCD responses in Z. mays and provides a framework for the mechanistic exploration of components involved in the initiation and execution of cell death., (© 2023 The Authors. The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.)

Plants detect conserved microbe-associated molecular patterns (MAMPs) and modified "self" molecules produced during pathogen infection [danger associated molecular patterns (DAMPs)] with plasma membrane-resident pattern recognition receptors (PRRs). PRR-mediated MAMP and/or DAMP perception activates signal transduction cascades, transcriptional reprogramming and plant immune responses collectively referred to as pattern-triggered immunity (PTI). Potential sources for MAMPs and DAMPs are microbial and plant cell walls, which are complex extracellular matrices composed of different carbohydrates and glycoproteins. Mixed linkage β-1,3/1,4-glucan (β-1,3/1,4-MLG) oligosaccharides are abundant components of monocot plant cell walls and are present in symbiotic, pathogenic and apathogenic fungi, oomycetes and bacteria, but have not been detected in the cell walls of dicot plant species so far. Here, we provide evidence that the monocot crop plant H. vulgare and the dicot A. thaliana can perceive β-1,3/1,4-MLG oligosaccharides and react with prototypical PTI responses. A collection of Arabidopsis innate immunity signaling mutants and >100 Arabidopsis ecotypes showed unaltered responses upon treatment with β-1,3/1,4-MLG oligosaccharides suggesting the employment of a so far unknown and highly conserved perception machinery. In conclusion, we postulate that β-1,3/1,4-MLG oligosaccharides have the dual capacity to act as immune-active DAMPs and/or MAMPs in monocot and dicot plant species., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Barghahn, Arnal, Jain, Petutschnig, Brumer and Lipka.)

Glutaredoxins (GRXs) are small proteins which bind glutathione to either reduce disulfide bonds or to coordinate iron sulfur clusters. Whereas these well-established functions are associated with ubiquitously occurring GRXs that encode variants of a CPYC or a CGFS motif in the active center, land plants also possess CCxC/S-type GRXs (named ROXYs in Arabidopsis thaliana) for which the biochemical functions are yet unknown. ROXYs and CC-type GRXs from rice and maize physically and genetically interact with bZIP transcription factors of the TGA family to control developmental and stress-associated processes. Here we demonstrate that ROXYs interact with transcriptional co-repressors of the TOPLESS (TPL) family which are related to Tup1 in fungi and Groucho/TLE in animals. In ROXYs, the functionally important conserved A(L/I)W(L/V) motif at the very C terminus mediates the interaction with TPL. A ternary TGA2/ROXY19/TPL complex is formed when all three proteins are co-expressed in yeast. Loss-of-function evidence for the role of TPL in ROXY19-mediated repression was hampered by the redundancy of the five members of the TPL gene family and developmental defects of higher order tpl mutants. As an alternative strategy, we ectopically expressed known TPL-interacting proteins in order to out-compete the amount of available TPL in transiently transformed protoplasts. Indeed, ROXY19-mediated transcriptional repression was strongly alleviated by this approach. Our data suggest a yet unrecognized function of GRXs acting as adapter proteins for the assembly of transcriptional repressor complexes on TGA-regulated target promoters., (Copyright © 2016. Published by Elsevier B.V.)