Homologs of animal eyes absent (eya) genes are found in higher plants

Homologs of the eyes absent (eya) gene in animals function at multiple stag es in the development of organs. Their functional roles in the genetic netw ork that regulates eye development in Drosophila have recently been extensi vely analyzed. A rice homolog of eya was identified from a cDNA library mad e from embryo RNA. The corresponding gene (OSEya1) encodes a conserved ED1 domain and a short N-terminal peptide. The ED1 domain of OSEya1 shows 25% i dentity and 36% similarity to the product of Drosophila eya. Mammalian and squid eya homologs show about 35% similarity to OSEya1. Homologous sequence s were also found in the alfalfa EST database (53% identity and 65% similar ity to OSEya1) and in the Arabidopsis genome sequence (63% identity). There fore, eya homologs are present in both monocots and dicots. Three regions i n the ED1 domain are well conserved in animals and plants. Plant eya produc ts deduced from the nucleotide sequences also have short N-terminal peptide s. The OSEya1 gene is located between the wx gene and the telomere on the s hort arm of chromosome 6. OSEya1 is expressed in the embryo, shoot apex, an d caryopsis in rice. Expression in the embryo increases during embryogenesi s until 7 days after pollination, with preferential localization in leaf pr imordia and the shoot apical meristem. Expression in the influorescence was observed in floral meristems. The functions of OSEya1 in higher plants are discussed and compared with those of their animal homologs. OSEya1 might r egulate the morphogenesis of lateral organs as a subunit of a transcription factor.