COMPARISON OF PHYTOPLASMAS INFECTING WINTER OILSEED RAPE IN THE CZECH-REPUBLIC WITH ITALIAN BRASSICA PHYTOPLASMAS AND THEIR RELATIONSHIP TOTHE ASTER YELLOWS GROUP

Winter oilseed rape grown in several areas in South Bohemia showed sym ptoms of stunting, leaf reddening and extensive malformation of floral parts. Phytoplasmas were consistently observed by using electron micr oscopy only in phloem tissue of symptomatic plants. DNA isolated from infected and healthy control plants was used in PCR experiments. Prime r pairs R16F2/R2, P1/P7 and rpF2/R2, amplifying, respectively, 16S rDN A, 16S rDNA plus spacer region and the beginning of the 23S and riboso mal protein gene L22 specific for phytoplasmas, were used. According t o RFLP and sequence analyses of PCR products, the phytoplasma from rap e was classified in the aster yellows phytoplasma group, subgroup 16Sr I-B. The PCR products from the Czech phytoplasma-infected rape also ha d RFLP profiles identical to those of phytoplasma strains from Italian Brassica. This first molecular characterization of phytoplasmas infec ting rape compared with strains from Brassica does not, however, clear ly indicate differences among isolates of the same 16SrI-B subgroup. F urther studies on other chromosomal DNA portions could help the resear ch on host specificity or on geographical distribution of these phytop lasmas.