A Repetitive DNA Sequence Differentiates Xanthomonas campestris pv. oryzae from Other Pathovars of X. campestris. Jan E. Leach. Departments of Plant Pathology, Throckmorton Hall, Kansas State University, Manhattan 66506-5502. Frank F. White(1), Marsha L. Rhoads(1), and Hei Leung(2). Departments of Plant Pathology, (1)Throckmorton Hall, Kansas State University, Manhattan 66506-5502, and (2)Washington State University, Pullman 99164 U.S.A. MPMI 3:238-246. Accepted 19 February 1990. Copyright 1990 The American Phytopathological Society.

Two repetitive DNA sequences were detected in the genome of Xanthomonas campestris pv. oryzae. An EcoRI-HindIII restriction fragment (2.4 kilobases) containing one highly repetitive sequence was cloned (pJEL101). Approximately 81 copies of the repetitive sequence in pJEL101 were dispersed throughout the genome as determined by quantitative filter hybridizations. Repetitive sequences related to pJEL101 were detected in all strains of X. c. pv. oryzae from different geographic areas. Strains representing five of 25 other X. campestris pathovars appeared to contain multiple copies of a related element. Only X. c. pv. oryzicola, another rice pathogen, contained a relatively high copy number of pJEL101 sequences compared to X. c. pv. oryzae, although the hybridization banding pattern was different. The pJEL101 sequence is a useful probe for pathovar identification as well as strain and population analyses.