Identification of a new root rot-causing pathogen in Polygonatum cyrtonema Hua and screening of phytochemicals for its control

Polygonatum cyrtonema Hua is a perennial herb belonging to the Liliaceae family, with significant medicinal and dietary value. However, root rot， a server disease, has led to a decline in yield and quality of this species. In this study, a fungus was isolated from symptomatic samples of root rot and identified as Fusarium commune through molecular and morphological analyses. After re-isolation, the identification of F. commune as the causative agent of root rot was confirmed by fulfilling Koch's postulates in subsequent tests.. Biological characteristics indicated that the optimal growth conditions for F. commune were a temperature of 25℃, pH of 8, carbon source of soluble starch, nitrogen source of peptone, and a photoperiod of 24 hours. In order to reduce the use of chemical fungicides and explore natural substances to control the disease, the sensitivity of F. commune to seven phytochemicals was studied. Four phytochemicals showed apparent inhibitory activity and honokiol displaying the highest antifungal activity, having a 50% of the maximal effect concentration (EC50) of 8.2628 ± 0.27 mg/L. These findings provide a scientific basis for the control of root rot in P. cyrtonema Hua.