Deciphering the causal agent of Fusarium root rot on Chrysanthemum morifolium

Root rot is one of the most important soil-borne fungal disease on Chrysanthemum morifolium . Fusarium root rot, an emerging disease affecting Chrysanthemum morifolium , has been observed with an incidence rate of 20% to 40%. To reveal the pathogen causing Fusarium root rot on Chrysanthemeum morifolium , from 2023 to 2024, a total of 110 Fusarium strains were isolated from the chrysanthemum diseased samples in 17 major production regions in Shanxi Province, China using five-point sampling method. Pathogenicity tests confirmed that all tested isolates were capable of infecting C. morifolium roots. Notably, Fusarium oxysporum isolate YS2-5 exhibited the highest pathogenicity. The activities of cell wall-degrading enzymes (CWDEs) were measured following F. oxysporum infection. Compared with that of control samples, a significant increase in CWDEs activity was detected in infected samples, suggesting that F. oxysporum disrupts the host cell wall structure. Metabolomic analysis revealed a differential accumulation of metabolites, including flavonoids, terpenoids, phenolic acids, and coumarins, which may play important roles in plant signal transduction and defense responses. In particular, jasmonic acid contents were significantly up-regulated, indicating their potential involvement in immune and defense pathways during pathogen infection. This study represents the characterization of the pathogen responsible for C. morifolium root rot and provides novel insights into the metabolic responses of C. morifolium to F. oxysporum infection. These findings offer valuable clues for the development of effective disease management strategies in the future.