ISOLATION AND CHARACTERIZATION OF 3 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 homeodomain-leucine zipper (HD-Zip) gene, Gmh1, as a probe, we isolated three cDNA clones, Phz1, Phz2, and Phz4, encoding polypeptid es that contain a homeodomain and a closely linked leucine zipper moti f. In both nucleotide and deduced amino acid sequences, Phz1, Phz2, an d 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-Zip motif. G enomic 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 dic otyledonous plants. Thus, it may be speculated that Phz1, Phz2, and Ph z4 proteins could impart functional characters unique to the dicotyled onous plants that would express them in processes common to those plan ts.