Phytoplasmas detected in cherry trees with lethal yellows (CLY) symptoms and in jujube trees with witches'-broom (JWB) symptoms in China were previously classified as a new subgroup in the 16S rRNA group V (elm yellows [EY] and related phytoplasmas) on the basis of restriction fragment length polymorphism (RFLP) analysis of PCR-amplified 16S rDNA sequences. Based on phylogenetic analysis of the 16S rRNA gene sequences of these two phytoplasmas and representatives of known phytoplasma groups, the CLY and JWB phytoplasmas form a distinct phylogenetic subgroup within the elm yellows phytoplasma subclade, which is consistent with the differentiation based on RFLP analysis of the same gene sequence. Further characterization by RFLP analysis of ribosomal protein gene sequence and coral genomic DNA using selected DNA probes derived from EY phytoplasma indicates that CLY and JWB phytoplasmas are closely related, but distinct strains. It is proposed that CLY and JWB phytoplasmas represent a new taxon distinct, at the rank of subspecies, from other members of the 16S rRNA group V. A CLYJWB subgroup-specific primer pair were designed and used to detect CLY and JWB phytoplasmas.
