The objective of this study was to determine the genetic relatedness among the
Cercospora and
Pseudocercospora species closely related to
Cercospora apii by using a polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) analysis of the internal transcribed spacer (ITS) region. A single PCR fragment (about 550 bp) was obtained from all
Cercospora species categorized as the
C. apii-group,
Pseudocercospora purpurea,
Pseudocercospora conyzae, and
Pseudocercospora cavarae. Cercospora caricis yielded a 680 bp PCR fragment. The similarity in the PCR fragment size and RFLP profiles among the
C. apii-group isolates, including
Pseudocercospora purpurea, and
Pseudocercospora conyzae strongly suggests that these species are conspecific. Synonymy with
C. apii (lectotype) at a subspecific rank has been proposed. Amplified ITS regions of genomic DNA extracted from spinach leaves showing 12 and 23% leaf spot disease symptoms caused by
Cercospora beticola yielded two PCR fragments (i.e., one from the fungus and one from the host plant) and were resolved by electrophoresis of the PCR product in 3% LMP agarose. Digestion of the total PCR product with
HinfI restriction enzyme yielded RFLP profiles similar to those obtained from amplified DNA from the causative agent,
C. beticola. The method described in this preliminary study offers rapid detection and diagnosis of fungal infections in plants for disease prediction and management and screening of plant materials for quarantine purposes.
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