Design of a Polymerase Chain Reaction for Specific Detection of Corn Stunt Spiroplasma

Corn stunt disease is a major limiting factor in production of corn (Zea mays) in the Americas. To develop a polymerase chain reaction (PCR) assay specific for detection of the causal agent, Spiroplasma kunkelii, PCR primers were designed on the basis of unique regions of the nucleotide sequence of the S. kunkelii spiralin gene. DNA was amplified in PCRs containing template DNAs derived from laboratory strains of S. kunkelii and from naturally diseased corn plants collected in the field. No DNA amplification was observed in PCRs containing template DNAs derived from other Spiroplasma species tested or from healthy corn or corn infected by maize bushy stunt phytoplasma. The availability of a sensitive and specific PCR for detection and identification of S. kunkelii should facilitate studies of the ecology of this pathogen, as well as its influence in the incidence, spread, and severity of corn stunting diseases.