Cloning and expression of cDNAs encoding ADP-ribosylation factor in carrot seedling

A homology based strategy yielded two cDNA clones designated arf-001 (1097 bp) and arf-002 (897 bp) from carrot seedlings. These genes contained open reading frames which encode the proteins of 192 and 181 amino acid residues, respectively, with the significant homology to ADP-ribosylation factors of plants, animals and microbial sources. Genomic Southern blot hybridization analyses revealed that both genes showed one main signal, respectively; however, several related genes might be present in carrot genome. The products of these genes obtained by over-expression in Escherichia coli showed the specific binding activity toward GTP. The expression of arf-001 was mainly observed in leaf and stem tissues while arf-002 was appreciably expressed in roots as analyzed by RT-PCR. The transcriptional level of arf-001 showed the transient increase by the exposure of carrot seedlings to ethylene. In contrast, arf-002 appeared to be a house-keeping gene, and its expression level was maintained at constant level upon the treatment with various stimuli and under stress conditions. These results suggest that the arf-001 and 002 play the distinct physiological roles in carrot cells.