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Updated: Sep 9, 2025

A Hydroponic Co-cultivation System for Simultaneous and Systematic Analysis of Plant/Microbe Molecular Interactions and Signaling
Published on: July 22, 2017
The HY5-NPR1 module governs light-dependent virulence of a plant bacterial pathogen
Pengtao Liu1, Zhao Zhao1, Yaqi Tang1
1Frontiers Science Center for Molecular Design Breeding (MOE), State Key Laboratory of Agricultural and Forestry Biosecurity, MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China.
Abstract:
Light is essential for plant development, but its influence on pathogen virulence and immunity remains poorly understood. Here, we found that the Pseudomonas syringae DC3000 type III effector, AvrPtoB, exhibits virulence exclusively upon light exposure. This light-dependent regulation is controlled by the Arabidopsis transcription factor ELONGATED HYPOCOTYL 5 (HY5), a central regulator of photomorphogenesis. AvrPtoB targets HY5 in the nucleus, facilitating its ubiquitination and degradation. Genetic disruption of HY5 eliminates susceptibility to AvrPtoB and compromises plant immunity upon light exposure. HY5 enhances immunity by binding promoters of defense-related genes, activating their expression, and stabilizing the transcriptional coregulator NONEXPRESSOR OF PATHOGENESIS-RELATED (PR) GENES 1 (NPR1) by inhibiting its negative regulators NPR3/4. Both HY5-mediated immunity and light-dependent AvrPtoB virulence require NPR1. By contrast, during darkness, CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1)-mediated HY5 degradation suppresses AvrPtoB virulence and HY5-enhanced immunity. These findings elucidate a mechanism in which light modulates bacterial virulence and plant immunity via an HY5-NPR1 module, advancing our understanding of light-pathogen-host interactions.
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