Cloning and expression analyses of cDNA encoding an ADP-ribosylation factor from wheat: tissue-specific expression of wheat ARF

We isolated and characterized a cDNA clone encoding a small GTP-binding pro tein, which has a high similarity to mammalian ADP-ribosylation factor (ARF ), from a cDNA library prepared from immature spikes of wheat (Triticum aes tivum L.). The cDNA contained an open reading frame that encodes a polypept ide of 181 amino acids with a calculated molecular mass of 20.7 kDa. The de duced amino acid sequence showed a quite high homology to known ARFs from o ther organisms. In particular, the wheat ARF was completely identical to th e rice ARF1. Genomic Southern hybridization suggested that wheat ARF is enc oded by at least two or three copies of ARF genes. Northern analyses showed that the accumulation of the ARF transcripts was nearly constant throughou t various environmental stresses in both shoots and roots. However the RNA transcript was preferentially expressed in roots rather than in shoots. A s imilar expression pattern was also observed at the protein level by Western analysis. The relative abundance of the ARF proteins in root and flower ti ssues may indicate a high level of vesicular transporting activity in the r oots and flowers of wheat plants. (C) 2001 Elsevier Science Ireland Ltd. Al l rights reserved.