Detection and identification of the two Candidatus Liberobacter species associated with citrus huanglongbing by PCR amplification of ribosomal protein genes of the beta operon

Huanglongbing, previously called greening, is a destructive disease of citr us in Asia and Africa. it is caused by an uncultured, phloem-restricted bac terium for which two species Candidatus Liberobacter asiaticum and Candidat us Liberobacter africanum have been characterized. In 1996, a polymerase ch ain reaction (PCR) detection method based on the amplification of the 16S r ibosomal operon was developed and proved to be efficient for the detection of both liberobacter species. However, in order to distinguish between Cand idatus Liberobacter asiaticum and Candidatus Liberobacter africanum, digest ion of the amplified DNA with XbaI was required. We have now developed a ne w PCR detection method based on the amplification of ribosomal protein gene s which allows direct identification of the liberobacter species by the siz e of the amplified DNA. This PCR method is as specific, and at least as sen sitive as the previously described one for detection of the two liberobacte r species. (C) 1999 Academic Press.