Related Experiment Video
Updated: Jan 12, 2026

Measuring Gene Expression in Bombarded Barley Aleurone Layers with Increased Throughput
Published on: March 30, 2018
Salicylic acid and ROS signaling modulate hypocotyl elongation in darkness via NPR1 and EX1
Mengshuang Li1,2, Mengping Li1,3, Shan Qi1,2
1Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
Abstract:
During early seedling growth in darkness, germinating seeds must balance growth and defense to ensure a successful transition from a heterotrophic to a photoautotrophic state. However, the molecular mechanisms regulating this process in etiolated seedlings remain poorly understood. Here, we investigate the role of salicylic acid (SA), a key defense hormone, in controlling hypocotyl elongation under dark conditions. SA inhibited hypocotyl growth in a dose-dependent manner, with a more substantial effect in the Arabidopsis npr1 mutant, revealing NPR1's role in maintaining growth under SA-accumulating conditions. In etiolated npr1 seedlings, auxin-responsive genes, including multiple SMALL AUXIN UP-REGULATED RNA (SAUR) and EXPANSIN genes, were down-regulated. Overexpression of SAUR19 or SAUR63 fully rescued SA-induced growth inhibition. We also identified EXECUTER1 (EX1), a mediator of singlet oxygen (1O2) signaling, as a contributor to this process. SA-driven lipid peroxidation increased 1O2 levels in darkness, triggering EX1-mediated retrograde signaling that represses auxin-related genes.
Related Concept Videos
Cell Signaling in Plants
Short-distance Transport of Resources
Hedgehog Signaling Pathway
Gene Regulation During Sporulation
Plant Hormones
Photoreceptors and Plant Responses to Light

