Abstract:

This study aims to investigate the regulatory effects of exogenous cinnamic acid on the proliferation， growth， infectivity and key pathogenic factors of Fusarium oxysporum， in order to provide a theoretical foundation for understanding the mechanisms underlying cinnamic acid-mediated consecutive replant problems caused by F. oxysporum of Lanzhou lily wilt and for developing control strategies. The in vitro culture method was employed， with cinnamic acid concentration gradients set at 0 mg·L^-1， 0.24 mg·L^-1， 2.40 mg·L^-1， and 24.00 mg·L^-1， to analyze the physiological growth indicators related to the proliferation and infection of F. oxysporum， as well as the transcriptional expression levels of key pathogenic genes such as FochsV and FUBT. The results indicated that low concentrations （0.24 mg·L^-1， 2.40 mg·L^-1） of cinnamic acid promoted the growth and high concentrations （24.00 mg·L^-1） of cinnamic acid inhibited the growth of F. oxysporum： 0.24 mg·L^-1 cinnamic acid significantly promoted colony growth and increased sporulation and markedly enhanced the activities of four cell wall-degrading enzymes （chitinase， cellulase， xylanase and pectinase）. The expression of FochsV gene showed a trend of promotion at low concentrations and inhibition at high concentrations over time， while the expression of FUBT gene displayed difference on the 7th day， showing promotion at high concentrations and inhibition at low concentrations. The overall activity of antioxidant reductase in the fungal cells were promoted at low concentrations and inhibited at high concentrations. In contrast， at 24.00 mg·L^-1 cinnamic acid significantly inhibited fungal growth， enzyme activities， and the expression of key pathogenic genes. Based on the accumulation characteristics of cinnamic acid in the soil under long-term consecutive replant of Lanzhou lily （0-9 years）， it is inferred that the accumulation of cinnamic acid is a key soil chemical regulatory factor exacerbating the incidence of wilt in this vegetable crop.

Key words: Fusarium oxysporum, cinnamic acid, antioxidant enzyme, cell wall degrading enzyme, gene expression analysis