DisplayTitle

Molecular and Chemical Characterization of a New Waxy Allele in Barley (Hordeum vulgare L.)

¹U.S. Department of Agriculture, Agricultural Research Service, 1691 S. 2700 W., Aberdeen, ID 83210. ²Corresponding author. Phone: (208) 397-4162. Fax: (208) 397-4165. E-mail: Gongshe.Hu@ars.usda.gov ³Department of Plant, Soil, and Entomological Sciences, and Program of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, ID 83844.

Barley m38 mutant was selected for its high level of mixed-linkage (1,3),(1,4)-β-D-glucan (MLG) in the grain. This elevated level of MLG was found to be associated with decreased amylose accumulation as well as other chemical composition alterations. Molecular characterization results revealed m38 as a new allele of the Waxy gene, encoding an endosperm-specific granule-bound starch synthase I (GBSSI). Additional mapping data from amylose phenotype and GBSSI gene specific markers supported the conclusion of the GBSSI mutation in m38. The m38 locus contains a nucleotide alteration that would result in the substitution of glycine at position 263 with serine in the putative adenosine-5′-diphosphate-glucose binding domain. This amino acid substitution alters loop structures on the exterior surface of the folded protein and may affect its enzyme activity. Characterizations of m38 in this report provide for a new allele of the Waxy gene and additional evidence of pleiotropic effects on other chemical components including increased MLG, fructans, and fats and decreased amylose and protein.