First Report of Rhexocercosporidium panacis Causing Rusty Root of Panax ginseng in Northeastern China

Area of Science:

• Plant Pathology
• Mycology
• Plant-Microbe Interactions

Background:

• Asian ginseng (Panax ginseng) is susceptible to various root diseases.
• Rusty root disease, characterized by superficial reddish-brown lesions, affects ginseng roots in northeastern China.

Purpose of the Study:

• To identify the causal agent of rusty root disease in Asian ginseng.
• To confirm the pathogenicity of the isolated fungus on Asian ginseng roots.

Main Methods:

• Symptomatic ginseng roots were collected and cultured on potato dextrose agar.
• Fungal isolates were purified, characterized morphologically, and identified using ITS and β-tubulin gene sequencing.
• Pathogenicity was tested by inoculating healthy ginseng roots with pure cultures of the isolated fungus.

Main Results:

• Rhexocercosporidium panacis was consistently isolated from symptomatic ginseng roots.
• Molecular analysis confirmed 99%-100% homology with known R. panacis isolates.
• Inoculation studies successfully reproduced the rusty root symptoms in Asian ginseng.

Conclusions:

• Rhexocercosporidium panacis is identified as the causative agent of rusty root disease in Asian ginseng.
• This is the first report of R. panacis causing disease in Panax ginseng, expanding its known host range.