Phenylalanine priming enhances thermotolerance in Pinellia ternata by integrating phenylpropanoid metabolism, redox homeostasis and hormonal signaling

Heat stress poses a major constraint to the commercial cultivation of Pinellia ternata . This study evaluates phenylalanine (Phe) as a natural metabolic priming agent to improve heat stress resilience. Plants were pre-treated with 10 and 30 mM Phe prior to heat exposure and assessed for survival, metabolic reprogramming, oxidative damage, photosynthetic performance, hormonal modulation, and transcriptomic responses. Phe treatment significantly enhanced the survival of P. ternata , increasing survival rates from 4.8% in untreated controls to 18.5% and 27.2% following 10 and 30 mM Phe treatments, respectively. Metabolomic profiling revealed enhanced flux through the phenylpropanoid pathway, leading to the accumulation of key bioactive compounds, including acetyleugenol, benzaldehyde, rosmarinic acid, and salicylic acid. Phe-treated plants exhibited reduced oxidative damage, as evidenced by lower reactive oxygen species levels and lipid peroxidation, coupled with enhanced antioxidant enzyme activities and improved photosynthetic efficiency under heat stress. Hormonal analysis showed increased salicylic acid and zeatin levels in Phe-treated plants, while suppressing excessive abscisic acid accumulation under heat stress conditions. Transcriptomic data indicated a mitigation of extensive heat-induced gene expression changes while maintaining the expression of genes associated with cell wall remodeling and hormone signaling. Overall, these findings demonstrate that Phe-mediated priming enhances thermotolerance via coordinated metabolic, redox, and hormonal regulation, providing a cost-effective strategy for improving heat stress resilience in P. ternata .