DETECTION AND DIFFERENTIATION OF GRAPEVINE YELLOWS PHYTOPLASMAS BELONGING TO THE ELM YELLOWS GROUP AND TO THE STOLBUR SUBGROUP BY PCR AMPLIFICATION OF NONRIBOSOMAL DNA

Primer pairs were designed from a cloned DNA probe of a strain of flav escence doree (FD) phytoplasma and from a cloned DNA probe of a strain of stolbur phytoplasma. Among an array of reference phytoplasma strai ns maintained in periwinkle, pair FD9f/r amplified a 1.3 kb DNA fragme nt only with phytoplasma strains of elm yellows (EY) group, i.e. two s trains of FD and two strains of EY. Tru9I restriction analysis of the fragment amplified by FD9f/r revealed a diversity among EY-group phyto plasmas. The FD strains differed from the strains isolated from elm. T he profile of the phytoplasmas infecting the grapevine samples from Ca talonia and most of the samples from Northern Italy were identical to that of a FD strain. Three other profiles were detected in grapevine f rom Palatinate, in Germany. The two primer pairs derived from a stolbu r strain, STOL4f/r and STOL11f2/r1, specifically amplified a 1.7 kb an d a 0.9 kb DNA fragment, respectively, with all strains in the stolbur subgroup. However, the pair STOL4f/r did not recognise strain MOL. Bo th pairs allowed to detect phytoplasmas in diseased grapevines from Fr ance, Italy, Spain and Israel. Attempts to differentiate between phyto plasmas in the stolbur subgroup by restriction analyses failed. The pa irs FD9/r and STOL112/r1 could be used in the same reaction (multiplex PCR) to detect BY-group phytoplasmas, stolbur-subgroup phytoplasmas o r both phytoplasmas simultaneously when template DNAs were mixed.