# Rose Bengal Is a Precise Pharmacological Tool Triggering Chloroplast‐Driven Programmed Cell Death in Plants, Dependent on Calcium and Mitochondria, and Associated With Early Transcriptional Reprogramming

## TL;DR

Rose Bengal triggers chloroplast-based programmed cell death in plants, involving calcium and mitochondria, and can be used to study stress responses.

## Contribution

Rose Bengal is identified as a precise tool for studying chloroplast-driven PCD, linking it to calcium, mitochondria, and transcriptional changes.

## Key findings

- RB-induced PCD is light and chloroplast dependent, involving calcium signaling and mitochondria.
- RB treatment causes early transcriptional reprogramming, switching off primary metabolism and activating stress response pathways.
- RB induces both light-dependent PCD and light-independent necrotic cell death, highlighting its dual effects.

## Abstract

Programmed cell death (PCD) mediates plant development and environmental interactions. Photosynthesis‐derived singlet oxygen (1O2) is one of key reactive oxygen species (ROS) implicated in acclimation and PCD responses to environmental stress conditions. Using
Arabidopsis thaliana
cell suspension culture system, we characterized the PCD induced by Rose Bengal (RB), a photosensitizer generating 1O₂ upon light exposure. Obtained results reiterated that RB‐induced PCD is light and chloroplast dependent. Further, we demonstrate that PCD induced by RB involves calcium signaling and mitochondria, thus sharing common features with other forms of regulated cell death in plants. The PCD induced by RB was associated with early transcriptional reprogramming, involving switching off the primary metabolism and activation of stress response and cell death related pathways (e.g., oxidative stress, hypoxia, immunity, and salicylic acid). The constructed gene regulatory network featured 1O2‐responsive genes and suggested involvement of transcription factor ANAC102 in retrograde regulation of RB‐induced PCD. Interestingly, treatment with RB also induced light independent toxicity, showing features of uncontrolled, necrotic cell death. Presented findings highlight RB as a valuable tool for studying 1O2‐induced PCD that may advance future work on chloroplast‐mediated oxidative stress responses and enhancing plant resilience to climate change‐related stressors through targeted modulation of ROS pathways.