Trichoderma asperellum Ta1 Alleviates Root Rot Caused by Fusarium solani and Promotes the Growth of Panax notoginseng

<i>Panax notoginseng</i> is a traditional medicinal and food-homologous plant in China; however, root rot, primarily caused by <i>Fusarium solani</i>, has become a devastating disease that severely compromises the yield and quality of <i>P. notoginseng</i>. In this study, a strain of <i>Trichoderma asperellum</i> (designated as Ta1) was isolated from the rhizosphere soil of healthy <i>P. notoginseng</i>. In vitro, Ta1 exhibited strong antagonistic activity against <i>F. solani</i>, with a growth inhibition rate of 65.53%, and the spore germination of <i>F. solani</i> was inhibited. In pot experiments, Ta1 reduced the incidence of root rot, and the biocontrol efficiency was around 59.55%. Additionally, Ta1 improved the growth vigor of <i>P. notoginseng</i> plants, resulting in significant increases in key agronomic traits, photosynthetic parameters, levels of primary metabolites, concentrations of plant growth-promoting hormones, and the accumulation of bioactive saponins. Transcriptomic and metabolomic analyses revealed that Ta1 upregulates key genes involved in the biosynthesis of phenylpropanoids, monoterpenoids, and diterpenoids, as well as in jasmonic acid signaling. Given its dual functions in disease control and growth promotion, Ta1 represents a promising biological control agent with great potential for application in <i>P. notoginseng</i> cultivation, contributing to the enhancement of its yield and quality.