Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2000
Publication Date: 6/1/2000
Citation: Horken, K.M., Edwards, M.C. 2000. Characterization of an rna-directed rna polymerase from barley. Phytopathology. 90(6):S36.
Technical Abstract: Certain cultivars of barley, including Morex, have been observed to recover from viral infection following an initial shock phase. Post-transcriptional gene silencing (PTGS) may be involved in the mitigation of this shock phase. The only host gene implicated in PTGS encodes an RNA-directed RNA polymerase (RDRP) thought to generate a sequence-specific nucleic acid signal perpetuating silencing. Using rapid amplification of cDNA ends (RACE), a full-length clone of RDRP from the monocot H. vulgare (cv. Morex) was assembled. Sequence analysis of several RACE clones revealed that at least two homologous RDRP genes are expressed in barley. These RDRP genes are constitutively expressed since the cDNA clones were derived from mRNA isolated from healthy tissue. The 3.35 kb open reading frame encodes a 1117 amino acid protein similar in length to the proteins found in L. esculentum and N. tabacum Alignment of the predicted amino acid sequence with other partial plant RDRP sequences revealed a high degree of similarity (up to 67% amino acid identity) even between distantly related plants. The involvement of these barley RDRP genes in the recovery phenomenon is under further study.