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The inactivation of starch branching IIb (SBEIIb) in rice is traditionally associated with elevated apparent amylose content, increased peak gelatinization temperature, and a decreased proportion of short amylopectin branches. To elucidate further the structural and functional role of this enzyme, the phenotypic effects of down-regulating SBEIIb expression(More)
(1,3;1,4)-β-D-glucans (mixed-linkage glucans) are found in tissues of members of the Poaceae (grasses), and are particularly high in barley (Hordeum vulgare) grains. The present study describes the isolation of three independent (1,3;1,4)-β-D-glucanless (betaglucanless; bgl) mutants of barley which completely lack (1,3;1,4)-β-D-glucan in all the tissues(More)
Arabinoxylan arabinofuranohydrolases (AXAHs) are family GH51 enzymes that have been implicated in the removal of arabinofuranosyl residues from the (1,4)-β-xylan backbone of heteroxylans. Five genes encoding barley AXAHs range in size from 4.6 kb to 7.1 kb and each contains 16 introns. The barley HvAXAH genes map to chromosomes 2H, 4H, and 5H. A small(More)
Eukaryotic messenger RNAs are translated with unequal efficiencies in vivo and in vitro and the molecular basis of this phenomenon is not understood. As an approach to understanding the role of the 5' untranslated leader sequence in regulating mRNA translational efficiency, chimaeric mRNAs have been generated by joining a heterologous leader to(More)
In this study of barley starch synthesis, the interaction between mutations at the sex6 locus and the amo1 locus has been characterized. Four barley genotypes, the wild type, sex6, amo1, and the amo1sex6 double mutant, were generated by backcrossing the sex6 mutation present in Himalaya292 into the amo1 'high amylose Glacier'. The wild type, amo1, and sex6(More)
Studies in Arabidopsis and rice suggest that manipulation of starch synthase I (SSI) expression in wheat may lead to the production of wheat grains with novel starch structure and properties. This work describes the suppression of SSI expression in wheat grains using RNAi technology, which leads to a low level of enzymatic activity for SSI in the developing(More)
The awn, an apical extension from the lemma of the spikelet, plays important roles in seed dispersal, burial, and photosynthesis. Barley typically has long awns, but short-awn variants exist. The short awn 2 (lks2) gene, which produces awns about 50% shorter than normal, is a natural variant that is restricted to Eastern Asia. Positional cloning revealed(More)
The genetic diversity of six starch biosynthetic genes (Wx, SSI, SSIIa, SBEI, SBEIIa and SBEIIb) in indica and japonica rices opens an opportunity to produce a new variety with more favourable grain starch quality. However, there is limited information about the effects of these six gene allele combinations on starch structure and properties. A recombinant(More)
The distribution of starch synthase I and starch branching enzyme IIb between the starch granule and amyloplast stroma plays an important role in determining endosperm amylose content of cereal grains. Starch synthase IIa (SSIIa) catalyses the polymerisation of intermediate length glucan chains of amylopectin in the endosperm of cereals. Mutations of SSIIa(More)
The cereal cell wall polysaccharide (1-3,1-4)-β-glucan is a linear polymer of glucose containing both β1-3 and β1-4 bonds. The structure of (1-3,1-4)-β-glucan varies between different cereals and during plant growth and development, but little is known about how this is controlled. The cellulose synthase-like CslF6 protein is an integral membrane protein(More)
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