Abstract: To investigate the regulatory effects of the activator protein PeFOC1 derived from Fusarium oxysporum on safflower seed germination and seedling growth under salt and drought stress, 250 mmol/L NaCl and 10% PEG-6000 were used to simulate salt stress and drought stress conditions, respectively. Treatments included0.1 mg/L (P1), 1 mg/L (P2), and 10 mg/L (P3) of PeFOC1, along with a control group (CK). Parameters such as germination potential, germination index, and seedling growth traits (plant height, root length, stem diameter, fresh weight, and dry weight) were analyzed. The expression of key immune-related genes (CtNPR, CtEDS1) were detected via qRT-PCR. The results demonstrated that comparedwith the untreated stress control group, treatment with 1 mg/LPeFOC1 (P2) significantly enhanced the seed germination potential under both salt and drought stress conditions, with increases of 37.15% and 61.54%, respectively. Meanwhile, P2 treatment markedly promoted root growth, with the root dry weight increasing bymore than 148% under salt stress. Analysis of immune gene expression revealed that under salt stress, 10 mg/L PeFOC1 most significantly up-regulated CtNPR and CtEDS1 (reaching 3.43-fold and 7.7-fold of CK, respectively). In contrast, under drought stress, 1 mg/LPeFOC1 specifically induced high expression of CtNPR and CtEDS1 (reaching 8.7-fold and 5.37-fold of CK, respectively). These findings demonstrate that PeFOC1 coordinately regulates safflower seed germination, seedling physiological adaptation, and immune response through a stress type-dependent concentration strategy, providing new insights and a theoretical basis for stress-resistant cultivation of safflower and the development of biological anti-stress agents.

Key words: Safflower (Carthamus tinctorius L.), abiotic stress, seed germination, immune response, PeFOC1