Resistant cultivar Ningqi-1 defends against Fusarium solani by activating stress-resistant substances and potential lignin biosynthesis pathways
Root rot is a major bottleneck limiting the sustainable development of the Lycium barbarum industry. To elucidate the defense strategies of L. barbarum in response to Fusarium solani, a key causal agent of root rot in Ningxia, the resistant cultivar Ningqi-1 and the susceptible cultivar Ningqi-5 were selected as research materials. We systematically compared the physiological responses and gene expression profiles of the two cultivars following pathogen inoculation. Morphologically, although both cultivars exhibited severe aboveground symptoms the roots of Ningqi-5 showed significantly deeper infection than those of Ningqi-1, with extensive hyphal colonization and cellular disruption, leading to more severe tissue maceration. Physiologically, infection with F. solani QT113 caused greater declines in photosynthetic parameters and root vitality, as well as higher malondialdehyde accumulation in Ningqi-5 compared to Ningqi-1, while the increases in antioxidant enzymes in both leaves and roots were significantly lower in Ningqi-1, indicating more severe membrane lipid peroxidation in the susceptible cultivar. At the transcriptional level, Ningqi-1 primarily activated phenylpropanoid biosynthesis and amino sugar and nucleotide sugar metabolism pathways, suggesting a potential for enhanced cell wall reinforcement and antioxidant capacity to establish effective defenses. In contrast, Ningqi-5 relied mainly on plant-pathogen interaction and MAPK signaling pathways to regulate phytoalexin synthesis and hypersensitive response, with its defense strategy tending more toward energy reallocation and stress regulation. Collectively, these findings indicate that the contrasting resistance of Ningqi-1 and Ningqi-5 is rooted in genetically programmed divergence in defense prioritization between structural fortification and compensatory stress responses.