Submitted to: European Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/1996
Publication Date: N/A
Interpretive Summary: Unculturable phytoplasmas (formerly called mycoplasmalike organisms) are the evident cause of many destructive diseases in several hundred plant species including several monocot plants. Based on restriction fragment length polymorphism (RFLP) analysis (finger printing) of 16S ribosomal RNA (16Sr) gene sequences the unculturable phytoplasmas have been classified into 11 major 16Sr groups. Group 16SrXI contains two phytoplasma strains which are associated with rice yellow dwarf and sugarcane white leaf diseases. This study indicated that a phytoplamsma associated with annual blue grass white leaf disease in southern Italy and a phytoplasma associated with Bermuda grass white leaf disease in Asia are new members (subgroups) of group 16SrXI. More new subgroups within each of 11 major phytoplasma 16Sr groups have been identified. This information permits us to differentiate phytoplasmas at a finer level and has contributed to the establishment of a comprehensive classification scheme for the uncultured phytoplasmas. The results will be of benefit to scientists and disease diagnoticians to gain understanding of the pathogen diversity and the relationship of this diversity to occurrence and spread of disease in host plants.
Technical Abstract: A phytoplasma was detected in annual blue grass (Poa annua), exhibiting white leaf symptoms, that were grown in the fields near Casseta in southern Italy. Based on restriction fragment length polymorphism (RFLP) analysis of PCR-amplified 16S rDNA sequences using selected restriction enzymes, the phytoplasma associated with annual blue grass white leaf (ABGWL) disease was identified to be a new member of phytoplasma 16S rRNA group XI (16SrXI) (type strain, rice yellow dwarf phytoplasma). The ABGWL phytoplasma is most closely related to bermuda grass white leaf (BGWL) phytoplasma found in Asia. ABGWL and BGWL phytoplasmas were designated as the third subgroup (16SrXI-C) of group XI. Other subgroups previously identified in group 16SrXI are: rice yellow dwarf (RYD) phytoplasma, 16SrXI-A and sugarcane grassy shoot and sugarcane white leaf phytoplasmas, 16SrXI-B. This is the first report that a plant pathogenic phytoplasma belonging to group 16SrXI is present on the European continent.