Supplementary data from: Bimodal retrograde signaling disrupts a suppressor network and activates a key transcriptional activator to direct stress responses

The intricate communication between plastids and the nucleus, shaping stress-responsive gene expression, has long intrigued researchers. This study combines genetics, biochemical analysis, cellular biology, and protein modeling to uncover how the plastidial metabolite MEcPP activates the stress-response regulatory hub known as the Rapid Stress Response Element (RSRE). Specifically, we identify the HAT1/TPL/IMPα-9 suppressor complex, where HAT1 directly binds to RSRE and its activator, CAMTA3, masking RSRE and sequestering the activator. Stress-induced MEcPP disrupts this complex, exposing RSRE and releasing CAMTA3, while enhancing Ca2+ influx and raising nuclear Ca2+ levels crucial for CAMTA3 activation and the initiation of RSRE- containing gene transcription. This coordinated breakdown of the suppressor complex and activation of the activator highlights the dual-channel role of MEcPP in plastid-to-nucleus signaling. It further signifies how this metabolite transcends its expected..., , # Supplementary data from: Bimodal retrograde signaling disrupts a suppressor network and activates a key transcriptional activator to direct stress responses

Dataset DOI: [10.5061/dryad.83bk3jb5q](10.5061/dryad.83bk3jb5q)

## Description of the data and file structure

### Files and variables

#### File: Movie_S1_ceh1_merge.avi

**Description:** Nuclear, and sub-PM Ca2+ dynamics in epidermal cells of ceh1 true leaf. (Alternative YouTube link: [https://youtube.com/shorts/E71BWpXc-iI](https://youtube.com/shorts/E71BWpXc-iI))

#### File: Movie_S2_WT_merged.avi

**Description:** Nuclear, and sub-PM Ca2+ dynamics in epidermal cells of WT true leaf. (Alternative YouTube link: [https://youtube.com/shorts/9vs_glB8xZc](https://youtube.com/shorts/9vs_glB8xZc))

#### File: Movie_S3_exoMEcPP_WT.avi

**Description:** Cytosolic, nuclear, and sub-PM Ca2+ dynamics in epidermal cells of true leaf treated with MEcPP. (Alternative YouTube link: [https://youtu.be/hA29CgXzOFM](https://youtu.be/hA29CgXzOFM...,