β-aminobutyric acid alleviates the inhibition of production of soybean with exposure to phenanthrene stress via multilayer defense to maintain consistency

Polycyclic aromatic hydrocarbons (PAHs), as organic pollutants widely present in the environments, pose a serious threat to the growth and development of industrial crops. In this study, through screening five exogenous substances capable of effectively alleviating plant stress, 200 μmol/L β-aminobutyric acid (BABA) was identified as the most effective exogenous agent for mitigating phytohormone stress in soybeans. Subsequently, the regulatory mechanisms of BABA in soybean ( Glycine max ) under Phenanthrene (PHE) stress were systematically investigated through combined exogenous BABA application and virus-induced gene silence (VIGS) targeting critical glutathione cycle genes (GR1/GSH1). BABA treatment activated GSH1 and GR gene, enhanced redox signaling, and stimulated key genes and enzymatic activities in phase II detoxification and glyoxalase pathways. Concurrently, modulation of the antioxidant system significantly reduced PHE-induced reactive oxygen species (ROS) accumulation in soybean. Furthermore, activation of photosystem II (PSII) electron transport enhanced photosynthetic pigment content and protected chloroplast structural integrity, preventing ROS accumulation caused by photosynthetic inhibition in plant cells. Consequently, suppression of soybean biomass was alleviated with enhanced root activity, collectively improving PHE stress tolerance. BABA, environmentally friendly biostimulant, was firstly applied to mitigate the inhibitory effects of PAH contamination on industrial crops via foliar spraying, the specific mechanism of which was elucidated. It further highlights the potential as an environmentally management strategy to safeguard the productivity of industrial crops in PAH-contaminated environments. • BABA is firstly proved to alleviate growth inhibition of soybean under PHE stress. • 2. BABA regulates phase II and glyoxalase system to alleviate PHE stress. • 3. BABA mediates redox signaling to relieve ROS accumulation. • 4. The glutathione cycle plays a crucial role in the regulation of BABA. • 5. BABA prevents PSII to avoid disrupts of chloroplast structure by PHE.