THE MAIZE HOMEOBOX GENE LIGULELESS3 IS ECTOPICALLY EXPRESSED IN AN OAT X MAIZE CHROMOSOME 3 ADDITION LINE RESULTING IN AN OAT PHENOCOPY OF THE MAIZE LG3 MUTANT

¹ Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108 USA

² Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331 USA

³ Department of Biology, St. Mary's College, Winona, MN 55987 USA

⁴ USDA-ARS, Department of Agronomy and Plant Genetics, St. Paul, MN 55108 USA

Grass leaves are divided into three parts: the basal sheath and distal blade divided by the ligular region which is composed of two wedged-shaped auricles and the ligule. The maize liguleless3 (lg3) gene encodes a homeodomain protein. Dominant mutations of the lg3 + gene result in a blade-to-sheath transformation at the midrib of the leaf. Ectopic expression of the maize lg3 gene is believed to cause the phenotype. The maize lg3 gene maps to chromosome three. Wide hybridization between oat and maize has been used to generate oat x maize addition lines. Many oat x maize addition lines have been isolated using this approach. Molecular analysis of these lines identified one line as containing maize chromosome 3. Morphological examination of this line showed that it exhibits a blade-to-sheath transformation similar to the dominant Lg3 mutations of maize. RNA expression analysis of this line demonstrated that the maize lg3 gene is ectopically expressed in oat. These data indicate that ectopic expression of the maize homeobox gene lg3 in oat results in an oat phenocopy of the maize Lg3 mutant.