Identification and Biocontrol of Pathogenic Fungi Causing Root Rot of Polygonatum cyrtonema Hua

Polygonatum cyrtonema (P. cyrtonema) Hua is an important economic crop with both edible and medicinal value. However, frequent root rot severely restricts its industrial development, resulting in sharp yield reduction and quality deterioration. To clarify the primary pathogenic fungi causing root rot of P. cyrtonema Hua, 58 fungal strains from naturally diseased P. cyrtonema Hua plants in different habitats were isolated in this study. By combining morphological observation and molecular identification based on 18S rDNA and ITS rDNA sequences, the species of 22 pathogenic fungi were identified, among which 10 strains belonged to the genus Fusarium, accounting for 45.45% of the identified isolates. The pathogenicity of 21 pathogenic fungi was verified according to Koch's postulates, with findings indicating that Fusarium species exhibited significant pathogenic potential. Meanwhile, six previously identified endophytic Paenibacillus strains isolated from P. cyrtonema Hua were employed to perform dual culture assays and antifungal evaluations of their fermentation supernatants against representative strains including F. concentricum F2, Neopestalotiopsis sp. F3 and F. oxysporum F8. The results indicated that the antagonistic activity exhibited by the six strains exceeded 50%, with the inhibition rates of their fermentation supernatants against strains F2, F3 and F8 surpassing 73%. This study confirmed that Fusarium is the dominant pathogenic fungal group causing root rot of P. cyrtonema Hua. Furthermore, highly effective antagonistic endophytes were preliminarily identified, offering candidate strains and a theoretical foundation for the green management of root rot in P. cyrtonema Hua.