Isolation and Characterization of Three Homeodomain-Leucine Zipper Genes, Phz1, Phz2, and Phz4 from Pimpinella brachycarpa Shoot Tips

Isolation and Characterization of Three Homeodomain-Leucine Zipper Genes, Phz1, Phz2, and Phz4 from Pimpinella brachycarpa Shoot Tips

By screening a Pimpinella brachycarpa shoot tip cDNA library with the soybean homeo-domain-leucine zipper (HD-Aip) gene, Gmhl, as a probe, we isolated three cDNA clones, Phz1, Phz2, and Phz4, encoding polypeptides that contain a homeodomain and a closely linked leucine zipper motif. In both nucleotide and deduced amino acid sequences, Phz1, Phz2, and Phz4 were highly homologous to two Arabidopsis thaliana HD-Zip genes, a soybean HD-Zip gene and a tomato HD-Zip gene in an HD-Aip motif. Genomic Southern blot analysis indicated that Phz2 and Phz4 are members of a multigene family. RNase protection assay revealed that Phz2 and Phz4 are expressed at all organs including leaves, petioles, roots and shoot tips. So far, these HD- Zip proteins have been found only in dicotyledonous plants. Thus, it may be speculated that Phz1, Phz2, and Phz4 proteins could impart functional characters unique to the dicotyledonous plants that would express them in processes common to those plants.