Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 16, 1999
Publication Date: N/A
Interpretive Summary: Phytoplasmas are bacteria-like organisms that infect many plants and often cause serious crop losses. Strawberry plants also can be infected with phytoplasmas, causing fruit losses as well as plant death. It has been only recently that research has focused on identifying and characterizing phytoplasmas from commercial strawberry and associating their presence with disease symptoms. In the course of this work, we have identified two such phytoplasmas, clover yellow edge and STRAWB2 phytoplasmas. This is the first report of the occurrence of clover yellow edge phytoplasma in Maryland and the first report of the occurrence of STRAWB2 phytoplasma outside of Florida where it was first identified. This information will be of use to scientists and extension personnel who are concerned with diseases of strawberry.
Plants of commercial strawberry (Fragaria x ananassa) that were either chlorotic and severely stunted or exhibiting fruit phyllody were collected in Maryland. These plants were assessed for phytoplasma infection by use of nested polymerase chain reactions (PCRs) primed by phytoplasma universal primer pairs R16mF2/R1 and F2n/R2 or P1/P7 and F2n/R2 for amplification of phytoplasma 16S rDNA (16S rRNA gene) sequences. Phytoplasma-characteristic 1.2 kbp DNA sequences were amplified from all diseased plants. No DNAs were amplified from healthy plants. Restriction fragment length polymorphism patterns of rDNA digested with AluI, KpnI, HhaI, HaeIII, HinfI, HpaII, MseI, RsaI, and Sau3A1 endonucleases indicated that the chlorotic and stunted plants were infected by a phytoplasma that belonged to subgroup 16SrIII-B (clover yellow edge (CYE) phytoplasma subgroup) and that the plant exhibiting fruit phyllody was infected by a phytoplasma that belonged to subgroup 16SrI-K (STRAWB2 phytoplasma subgroup). STRAWB2 phytoplasma was first reported from strawberry plants grown in Florida and characterized as representative of a new subgroup of the aster yellows group, 16SrI; this is the first report of this phytoplasma occurring in strawberry outside of Florida. CYE phytoplasma was first experimentally transmitted to commercial strawberry and F. virginiana in Ontario; this is the first report of natural CYE phytoplasma infection of strawberry in Maryland.