Transcriptomic insights into how L-phenylalanine enhances Yarrowia lipolytica biocontrol of pear blue mold.

Our previous study demonstrated that L-phenylalanine (L-Phe) can induce enhanced biocontrol efficacy of Yarrowia lipolytica against postharvest blue mold in pear fruit. This work also clarified the physiological mechanisms underlying the L-Phe-mediated improvement in biocontrol performance; however, the detailed molecular mechanisms responsible for this enhancement require further investigation. Results showed that Y. lipolytica cultured with 5 mmol/L L-Phe significantly reduced decay incidence in pear fruit without adversely affecting postharvest quality. In addition, L-Phe induction increased the production of volatile organic compounds by Y. lipolytica, effectively inhibiting the mycelial growth of Penicillium expansum. During storage, L-Phe treatment enhanced the oxidative stress tolerance of Y. lipolytica by alleviating ROS accumulation in yeast cells at fruit wound sites, which promoted better colonization of Y. lipolytica in wounds. Furthermore, L-Phe induction increased the activities of chitinase (CHI) and β-1,3-glucanase (GLU) in Y. lipolytica, indicating enhanced cell wall metabolic activity. Transcriptome analysis revealed significant metabolic reprogramming in L-Phe-treated cells, with key pathways, including propanoate metabolism, glycerolipid metabolism, lysine degradation, butanoate metabolism, and tryptophan metabolism, being significantly upregulated. These changes improved both oxidative stress adaptation and energy utilization efficiency in the yeast. Overall, L-Phe induction effectively enhances the biocontrol capacity of Y. lipolytica, providing new insights into improving the performance of antagonistic microorganisms in postharvest disease control.