Abstract: The study investigated the effects of exogenous salicylic acid (SA) on root metabolism of Panax notoginseng, explored how differentially expressed metabolites influenced the growth of the main root rot pathogens of P. notoginseng, aiming to provide novel ideas for the ecological prevention and control of P. notoginseng root rot. Different concentrations of SA were sprayed on the leaves of P. notoginseng under continuous cropping conditions to screen the optimal SA concentration for reducing root rot disease. Gas chromatography-mass spectrometry (GC-MS) was then used to analyze the changes in metabolites in the fibrous roots of P. notoginseng at the optimal SA concentration, and the effects of significantly changed metabolites on the growth of P. notoginseng root rot pathogens were further studied. The results showed that compared with the control, exogenous application of 280.00 μg/mL SA could significantly increase the seedling survival rate of P. notoginseng in continuous cropping soil, and significantly promote the growth of root length and biomass. Metabolomics analysis revealed that the metabolites in the fibrous roots of P. notoginseng mainly included nine types of substances, such as organic acids, amino acids and their derivatives, sugars and their derivatives. After exogenous application of SA, the sugar metabolism and fatty acid metabolism of P. notoginseng roots changed significantly, and the contents of D-(+)-trehalose and linoleic acid decreased significantly. Further studies showed that these two significantly down-regulated metabolites could significantly promote the growth of the main root rot fungi within a certain concentration range. The results of this study provide a theoretical basis and technical support for the ecological prevention and control of P. notoginseng root rot.

Key words: salicylic acid, trehalose, linoleic acid, Panax notoginseng root rot