First Report of Powdery Mildew on Cardamine violifolia in China

Area of Science:

• Plant Pathology
• Mycology
• Medicinal Botany

Background:

• Cardamine violifolia, a selenium-accumulating medicinal plant, is economically important.
• Selenium is vital for its antioxidant, anti-inflammatory, anti-cancer, and immune functions.
• Powdery mildew outbreaks can cause significant yield loss and disrupt plant metabolism.

Purpose of the Study:

• To identify and characterize the causal agent of a powdery mildew outbreak on Cardamine violifolia in China.
• To confirm the pathogenicity of the isolated fungus on C. violifolia.
• To provide information for disease management and prevent economic losses.

Main Methods:

• Morphological analysis of fungal structures (conidiophores, conidia, appressoria).
• Molecular identification using ITS region sequencing and phylogenetic analysis (maximum likelihood).
• Pathogenicity testing following Koch's postulates.

Main Results:

• The outbreak affected approximately 25% of C. violifolia plants, causing severe leaf and stem damage.
• Morphological and molecular analyses identified the pathogen as Erysiphe cruciferarum, with 99.2% ITS sequence identity.
• Pathogenicity tests confirmed E. cruciferarum as the causative agent, inducing typical powdery mildew symptoms on inoculated plants.

Conclusions:

• This is the first report of Erysiphe cruciferarum infecting Cardamine violifolia in China.
• Cardamine violifolia is confirmed as a suitable host for E. cruciferarum.
• Growers need to be informed to implement management strategies and mitigate economic impacts.