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Poster: Diseases of Plants: Disease Detection & Diagnosis


Validation of a novel gene target for detection and quantification of Clavibacter michiganensis subsp. nebraskensis, the causal agent of Goss’s wilt
R. MCNALLY (1), C. Ishimaru (2), D. Malvick (2) (1) University of Minnesota, U.S.A.; (2) University of Minnesota, U.S.A.

Goss’s wilt of maize is a reemerging and significant disease caused by the bacterium Clavibacter michiganensis subsp. nebraskensis (Cmn). Despite its expansion in North America, molecular tools for diagnosing and studying the epidemiology of this disease remain limited. Here we report the identification of CMN_01184 as a novel gene target and demonstrate its use for development of conventional PCR (cPCR) and quantitative PCR (qPCR) assays for detection and quantification of Cmn. Primers designed for cPCR and qPCR were evaluated for specific amplification of CMN_01184 using a diverse collection of 129 bacterial and fungal isolates, including multiple corn pathogens, environmental organisms from agricultural fields, and all known subspecies of C. michiganensis. Of these, only isolates of Cmn tested positive for CMN_01184. To evaluate the utility of CMN_01184 for in situ detection of Cmn, cPCR and qPCR based on this target gene was performed on infested field soil and naturally infected corn leaves containing Cmn. CMN_01184 was amplified only in soil samples and leaves containing Cmn. Finally, in greenhouse studies, systemic infection of corn leaves by Cmn was quantified over a two-week infection period using the qPCR assay based on CMN_00184. The results demonstrate collectively that specific and sensitive PCR assays based on CMN_01184 can aid in diagnosis as well as studies of the epidemiology and ecology of Goss’s wilt.