A disease associated with phytoplasma in Parthenium hysterophorus

A disease on parthenium weed (Parthenium hysterophorus L.) was observed in June 2008 in Danzhou of Hainan Province. Infected weeds showed phytoplasma-like associated symptoms such as severe stunting, excessive proliferation of shoots, inflorescence-clustering, green petal, small leaves and witches'-broom. The original cause of phytoplasma was further confirmed by polymerase chain reaction (PCR). PCR products of 1.8 kb were obtained using the universal primers pair (P1/P7) designed to amplify the entire 16S rDNA and the 16/23S intergenic spacer region in a direct PCR assay. The primers pair R16F2n/R2 was used to amplify a PCR product of 1.2 kb. Restriction fragment length polymorphism (RFLP) was used to analyze the partial 16S rDNA sequences (1.2 kb) of all phytoplasma DNA digested with five endonucleases (Kpn I, Hpa II, Taq I, Rsa I, EcoR I). The RFLP patterns of the strain were found to be identical with that of the reference peanut witches'-broom phytoplasma. Based on the RFLP data, it is suggested that the phytoplasma strain belongs to subgroup 16SrII-A. This is the first demonstration of a 16SrII-A group phytoplasma associated with parthenium weed.