Establishment of an Efficient High-yield Sporulation Protocol for Mycocentrospora acerina causing Leaf Blight of Asarum heterotropoides Fr. Schmidt var. mandshuricum (Maxim.) Kitag.

Mycocentrospora acerina is responsible for inducing severe leaf blight on Asarum heterotropoides. However, its poor sporulation under standard culture conditions significantly limits research on pathogenicity and disease management. This study aimed to develop an efficient high-yield and reproducible sporulation protocol by optimizing cultural conditions and nutritional factors. The results indicate that near-ultraviolet (Near-UV) light serves as a critical inducer of sporulation for M. acerina. In contrast to the standard culture on PDA medium at 20℃, where the pathogen fails to produce conidia, exposure to Near-UV light effectively stimulated sporulation, yielding a relatively robust production of 1.37×10³ conidia/mL after 21 days. Furthermore, V8 medium provided the optimal substrate conditions, yielding 4.56×10³ conidia/mL under the same cultural conditions after 14 days, a value significantly higher than those on other tested media. The optimized protocol (Near-UV light, V8 medium, 20℃, pH 7.0, 1 g/L glucose, and 1 g/L potassium nitrate) achieved a conidial yield of 1.0×10⁵ conidia/mL after 14 days. The conidia produced using the optimized sporulation protocol were morphologically identical to wild-type conidia and exhibited similar germination and pathogenicity. This established sporulation protocol provides vital materials for further studies, including infection, pathogenicity mechanism, and host-pathogen interaction dynamics and lays a theoretical basis for developing targeted strategies to control A. heterotropoides leaf blight.