# Stress Hormone Signal Transduction in Arabidopsis

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA, SAN DIEGO · 2023 · $53,314

## Abstract

Administrative Supplement to R01GM060396
Project Summary of the Parental Award
 Abscisic acid (ABA) is a central stress hormone in Arabidopsis that down-regulates cell proliferation and
causes cell cycle arrest. Early signal transduction networks that down-regulate cell proliferation are of key
importance for controlling mitogenesis and their mis-regulation is linked to many human diseases. The long-
term goal of this research is to achieve a quantitative understanding of the network of events that mediate early
abscisic acid signaling making use of the potent Arabidopsis and guard cell systems. We will characterize
newly identified key cellular signaling mechanisms hypothesized to control the early ABA signaling module
consisting of ABA receptors, PP2C protein phosphatases and SnRK2 and Raf-like protein kinases. Aims:
Aim I. PP2C phosphatases dephosphorylate and shut off SnRK2 protein kinases and thus ABA signaling.
Whether SnRK2 kinase re-activation is accomplished by auto-phosphorylation or by other protein kinases
remained unknown. Our recent findings show that dephosphorylated SnRK2 kinases cannot re-activate
themselves. These findings reveal that re-activation of the SnRK2 kinases, which orchestrate downstream ABA
signaling, requires phosphorylation of a specific site in SnRK2 kinases. Via a genetic redundancy screen, we
have identified the long-sought SnRK2 re-activation mechanism as Raf-like-kinases (Raf-Ks). We will
determine the mechanisms by which Raf-Ks integrate within ABA receptor - PP2C - SnRK2 and osmotic stress
signaling using interdisciplinary approaches, including new dynamic SNRK2-FRET activity nano-sensors.
Aim II. Through our recent development of an innovative genome-wide artificial microRNA-screening platform,
that is designed to silence redundant homologous genes, we have identified previously uncharacterized E3
ligase F-Box proteins that are required for ABA signal transduction. Candidate F-Box targets have been
isolated through a dominant F-Box decoy approach. The functions of the identified F-Box proteins and their
targets, including GASA signaling peptides, will be determined in the dynamic ABA signaling network through a
combination of guard cell signaling, genetic, proteomic, biochemical and ubiquitination analyses.
Aim III. Through a forward genetics screen, we have identified a chromatin remodeling factor SYD, as required
for ABA responses. We will investigate the hypothesis that rapid ABA-triggered chromatin remodeling plays a
critical role in directing the massive ABA-induced SnRK2-driven transcriptional response, based on new
findings, including genomic scale rapid differential ABA-induced chromatin accessibility shifts. Mechanisms by
which Snf2 chromatin remodeling factors mediate the ABA-induced chromatin accessibility response and how
SYD functions in specificity of ABA-induced SnRK2-driven transcriptional reprogramming will be determined.
 Results from these integrated approaches will provide new and mechan...

## Key facts

- **NIH application ID:** 10797147
- **Project number:** 3R01GM060396-23S1
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN DIEGO
- **Principal Investigator:** JULIAN I SCHROEDER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $53,314
- **Award type:** 3
- **Project period:** 2000-02-01 → 2024-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10797147

## Citation

> US National Institutes of Health, RePORTER application 10797147, Stress Hormone Signal Transduction in Arabidopsis (3R01GM060396-23S1). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10797147. Licensed CC0.

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