A chromosome map of the European stone fruit yellows phytoplasma

A physical map of the European stone fruit yellows phytoplasma strain GSFY1 chromosome was constructed using PFGE-purified genomic DNA from diseased t obacco and tomato plants. The map was generated with single and double dige stions of the chromosome with SmaI, BssHII, ApaI, BamHI and XhoI restrictio n endonucleases and the fragments were resolved by PFGE, Reciprocal double digestions were used to locate 26 restriction sites on the chromosome, Sout hern blot analysis was also used to assist in the arrangement of the contig uous restriction fragments obtained. From the restriction fragments generat ed by double digestion, the circular chromosome was calculated to be approx imately 635 kb, Loci of two rRNA operons, the operon containing the tuf gen e, genes encoding an immunodominant membrane protein and a putative nitrore ductase, and randomly cloned DNA fragments IH184 and AT67 were placed on th e map, Digestion of chromosomal DNA of strain GSFY1 with MluI gave a comple x restriction pattern, suggesting that this isolate consists of a populatio n with heterogeneity with respect to MluI restriction sites, The GSFY1 phys ical map was different from that of the closely related apple proliferation phytoplasma but the genetic arrangement was similar.