Detection of phytoplasmas in dieback, yellow crinkle, and mosaic diseases of papaya using polymerase chain reaction techniques

Oligonucleotide primers complementary to regions specific to plant-pathogenic mycoplasma-like organisms (phytoplasmas) were used in polymerase chain reactions on tissue samples from dieback, yellow crinkle, and mosaic affected papaya plants. The primer pair P068/P069, which hybridise to internal regions of the 16S rRNA gene, amplified an approximately 560 bp product in dieback, yellow crinkle and mosaic affected papaya. The primer pair P3/P7, which hybridise to the spacer region between the 16S and 23S rRNA genes, amplified an approximately 300 bp fragment in yellow crinkle and mosaic affected papaya, with no product from dieback affected plants. No PCR product was obtained with either set of primers from healthy plants: An identical AluI restriction enzyme profile was obtained with all three 560 bp products. This study provides the first evidence for the association of phytoplasmas with papaya mosaic and Australian papaya dieback.