Distinct Species Exist Within the Cercospora apii Morphotype

Area of Science:

• Mycology
• Plant Pathology

Background:

• The genus Cercospora includes numerous species, with Cercospora apii sensu lato representing a complex of morphologically similar fungi.
• Cercospora apii and Cercospora beticola are key pathogens causing leaf spot on celery and sugar beet, respectively.

Purpose of the Study:

• To differentiate morphologically similar Cercospora strains from celery and sugar beet using molecular and cultural methods.
• To confirm the distinctness of Cercospora apii and Cercospora beticola and identify potential new species.

Main Methods:

• Multilocus sequence data analysis.
• Amplified fragment length polymorphism (AFLP) analysis.
• Characterization of cultural characteristics.
• Development of a polymerase chain reaction (PCR)-based diagnostic protocol.

Main Results:

• Cercospora apii and Cercospora beticola were confirmed as distinct species despite morphological similarities and host cross-infectivity.
• A third, previously undescribed Cercospora species was identified on celery in Korea and Venezuela.
• A PCR-based protocol was developed to accurately distinguish between these three Cercospora species.

Conclusions:

• Cercospora apii and Cercospora beticola are functionally distinct pathogens that should be maintained as separate species.
• The discovery of a new Cercospora species highlights the potential for further undescribed diversity within this genus affecting celery.
• The developed PCR diagnostic protocol provides a valuable tool for accurate identification and management of Cercospora leaf spot diseases.