Abstract: To investigate the biological function of the mevalonate-5-phosphate kinase (PMK) gene in the flower of Panax notoginseng under different cultivation modes and at different flowering stages, the flowers from two different agroforestry systems (Pinus armandii-Panax notoginseng and Pinus yunnanensis-Panax notoginseng) were used as materials. Primers were designed based on transcriptome data, and the PMK gene was obtained using techniques such as PCR and RT-qPCR, and named PnPMK. The results showed that the full-length PnPMK gene was 414 bp, encoding 138 amino acids. The protein had a molecular mass of 15 155.81 u and a theoretical isoelectric point of 7.62, indicating it was a weakly basic protein. It exhibited weak hydrophobicity, contained no signal peptide, and was predicted to possess a transmembrane domain, primarily localizing to the plasma membrane and mitochondria. Phylogenetic tree analysis indicated that the PMK protein sequence of Panax notoginseng was most closely related to that of Panax ginseng, with a similarity of 77.21%. Real-time quantitative PCR analysis showed that the expression of the PnPMK gene differed between the two agroforestry systems. In the Pinus armandii-Panax notoginseng system, the gene exhibited a higher relative expression level in the flowers at the full-bloom stage, whereas in the Pinus yunnanensis-Panax notoginseng system, its relative expression level was higher in the flowers at the initial-bloom stage. The relative expression level of the PnPMK gene showed a significant positive correlation with temperature, and significant negative correlations with relative humidity and altitude, but no significant correlation with atmospheric pressure. Different agroforestry system modes and flowering stages had a significant impact on the expression of the PnPMK gene in the flowers of Panax notoginseng.

Key words: under forest, Panax notoginseng, flower, PMK gene, cloning, expression pattern