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Title: FIRST REPORT OF BARLEY AS HOST OF A PHYTOPLASMA BELONGING TO GROUP 16SRI, SUBGROUP B, AND RIBOSOMAL PROTEIN SUBGROUP B

Author
item URBANAVICIENE, I - VILNIUS LITHUANIA
item JOMANTIENE, RASA - VILNIUS LITHUANIA
item Davis, Robert

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2004
Publication Date: 3/1/2005
Citation: Urbanaviciene, I., Jomantiene, R., Davis, R.E. 2005. First report of barley as host of a phytoplasma belonging to group 16SrI, subgroup B, and ribosomal protein subgroup B. Plant Disease. 89:339.

Interpretive Summary: Barley is a major grain crop that is economically important in central Europe and other regions of the world. Diseases that affect barley have the potential for seriously reducing the productivity of this crop, and may have potential to spread to other grain crops. In this work, we found that a phytoplasma is the apparent cause of a newly recognized barley disease, which we have named barley deformation (BaDef) disease. Phytoplasmas are tiny wall-less bacteria that are transmitted from plant to plant by insects, mainly leafhoppers. Because phytoplasmas cannot be isolated and identified in pure culture in the laboratory, we used molecular methods to identify and characterize the BaDef phytoplasma. The findings will be of interest to diagnostics laboratories, grain producers and processors, and research scientists monitoring disease incidence and spread in grain crops.

Technical Abstract: Numerous diseased plants of barley (Hordeum vulgaris L.) exhibiting twisted, abnormally thin and yellowed awns, reduced spikelets, and general stunting and yellowing were observed in fields in the Vilnius and Kaisiadorys regions of Lithuania. The possible association of a phytoplasma with the disease, termed barley deformation (BaDef), was assessed using the polymerase chain reaction (PCR), and a phytoplasma associated with the disease was through restriction fragment length polymorphism (RFLP) analysis of a 1.2 kbp 16S rDNA fragment, amplified in PCR primed by primer pair R16F2n/R16R2, and through analysis of 1.2 kbp rp gene sequences amplified in PCR primed by primer pair rpF1/rpR1. On the basis of collective RFLP patterns of amplified 16S rDNA and rp gene sequences, the BaDef phytoplasma was classified as a member of group 16SrI (group I, aster yellows phytoplasma group), subgroup B, rp subgroup B. Ribosomal protein subgroup B was distinguished from other rp subgroups based on the presence of a recognition site for HpaII. The 1.8 kbp rDNA product of PCR primed by P1/P7 and the 1.2 kbp rpF1/rpR1 PCR product were cloned and sequenced, and the sequences were deposited in the GenBank Database under Accession No. AY734454 for the BaDef 16S rDNA and Accession No. AY735448 for the BaDef rp gene sequence. Previously, only oat proliferation (OatP) phytoplasma, a member of subgroup 16SrI-A, had been reported in oats in Europe; BaDef may increase the threat of phytoplasmal diseases of cereal crops in the region.