Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

Genetics Of Tillering In Barley

Gary J Muehlbauer , Hatice Bilgic , Shane Heinen , Timothy Dabbert , Seungho Cho

  Department of Agronomy and Plant Genetics, 1991 Buford Circle, University of Minnesota, St. Paul, MN 55108 USA

Barley (Hordeum vulgare L.) shoot architecture is based upon the actions of the apical and axillary meristems. The shoot apical meristem produces all above-ground organs including: leaves, nodes, internodes, inflorescence and axillary meristems. Vegetative axillary meristems form in the leaf axil of lower leaves at the crown and produce tillers. Three stages characterize tiller development: (1) initiation of an axillary meristem; (2) development of the axillary bud; and (3) outgrowth of the axillary bud into a tiller. Three classes of barley mutants are available for study: (1) mutants that do not tiller; (2) mutants that exhibit fewer tillers than wildtype; and (3) mutants that exhibit more tillers than wildtype. My laboratory is studying four low-tillering barley mutants including: uniculm2 (cul2), uniculm4 (cul4), low number of tillers (lnt) and absent lower laterals (als). Histological examination of these mutants shows that each restricts tiller number in a unique fashion. We used the Barley1 Affymetrix GeneChip to examine transcript accumulation in these mutants compared to wildtype at four key stages of axillary meristem initiation and development. Our results show each mutant exhibits large sets of genes that are differentially expressed compared to wildtype. Interestingly, these differentially expressed genes are composed largely of distinct gene groups, indicating that there is not a signature expression profile for these low-tillering mutant phenotypes. Our results also implicate a variety of developmental processes with each mutant. Finally, we are using the GeneChip data to identify markers linked to each gene and possibly identify the genes.