Nested-PCR assays for detection of phytoplasmas in strawberry

Flower and fruit virescence and phyllody are known to be associated with the presence of phytoplasmas in symptomatic tissues. During surveys in North and South Italy symptomatic and asymptomatic strawberry samples were examined by nested polymerase chain reaction (PCR) to verify the presence of phytoplasmas using 16S ribosomal DNA primers. Most of the symptomatic samples yielded DNA bands of 1.2 kb when nested-PCR was performed on invisible products obtained from direct PCR. Negative results were obtained when asymptomatic strawberry samples and controls devoid of DNA template were used. Further nested-PCR assays carried out with primer pair R16(I)F1/R1, that specifically amplifies DNA from phytoplasmas belonging to the aster yellows group, indicate that the phytoplasmas detected in strawberries belong to this phytoplasma group.