Anti-RPF2 monoclonal antibody, clone FQS21364(C)

Rpf2 (Ribosome Production Factor 2) is involved in ribosome biogenesis, and functions as one of the pre-rRNA processing factors. Although properties of the Rpf2 protein in yeast have been described in detail, there have been no reports on Rpf2 homologues in higher eukaryotes. To investigate the function of Rpf2 homologues in higher plants, we identified genes encoding Rpf2-like proteins from Arabidopsis and rice and designated them AtRpf2 and OsRpf2, respectively. The predicted amino acid sequence revealed that both genes contain the Brix domain, a characteristic domain associated with ribosome biogenesis, and a sigma 70-like RNA binding motif, a eukaryotic RNA binding domain unique to a superfamily of proteins required for ribosome biogenesis. Both gene transcripts were detected in all organs and tissues tested and the expression patterns were consistent with the typical expression pattern of previously described ribosomal protein genes. Transient expression of GFP::AtRpf2 and GFP::OsRpf2 revealed predominant nucleolar localization within the nucleus of both fusion proteins in onion epidermal cells and tobacco BY-2 cells. These results suggest that Rpf2-like proteins in higher plants are also involved in ribosome biogenesis and function as pre-rRNA processing factors.

Winter oilseed rape grown in several areas in South Bohemia showed symptoms of stunting, leaf reddening and extensive malformation of floral parts. Phytoplasmas were consistently observed by using electron microscopy only in phloem tissue of symptomatic plants. DNA isolated from infected and healthy control plants was used in PCR experiments. Primer pairs R16F2/R2, P1/P7 and rpF2/R2, amplifying, respectively, 16S rDNA, 16S rDNA plus spacer region and the beginning of the 23S and ribosomal protein gene L22 specific for phytoplasmas, were used. According to RFLP and sequence analyses of PCR products, the phytoplasma from rape was classified in the aster yellows phytoplasma group, subgroup 16SrI-B. The PCR products from the Czech phytoplasma-infected rape also had RFLP profiles identical to those of phytoplasma strains from Italian Brassica. This first molecular characterization of phytoplasmas infecting rape compared with strains from Brassica does not, however, clearly indicate differences among isolates of the same 16SrI-B subgroup. Further studies on other chromosomal DNA portions could help the research on host specificity or on geographical distribution of these phytoplasmas.