Gibberellic acid reverses glucose-inhibited photosynthesis and growth via reduced glutathione and hormonal crosstalk in chromium-treated mustard

Chromium (Cr) contamination jeopardizes agricultural productivity by impairing photosynthesis and growth in plants. This study investigates the potential of gibberellic acid (GA) in mitigating the adverse effects of Cr exposure in mustard ( Brassica juncea L.) plants and elucidates the underlying mechanism involved. Mustard plants were treated with 100 µM Cr to induce stress, followed by individual and combined foliar applications of 10 µM GA and 6 % glucose (Glu) to assess their effects on photosynthesis, growth, oxidative stress and hormonal regulation. Photosynthesis and growth of Cr-treated plants were inhibited, partially due to Glu accumulation. GA application enhanced Glu utilization, reduced reactive oxygen species (ROS) production, and optimized ethylene and nitric oxide (NO) levels. The optimized ethylene and NO signaled increased proline, GSH and antioxidant enzyme activity, thus promoting photosynthesis and growth under Cr stress. This study highlights the role of GA with Glu in counteracting Cr toxicity through complex hormonal interactions, emphasizing its potential as a phytoremediation strategy to improve the growth and productivity of crops in Cr-contaminated soils. The mechanisms underlying GA-mediated stress alleviation could pave the way for developing targeted approaches to enhance plant resilience against heavy metal stress.