Starch granule initiation and growth are altered in barley mutants that lack isoamylase activity

Summary Two mutant lines of barley, Risø 17 and Notch‐2, were found to accumulate phytoglycogen in the grain. Like the sugary mutants of maize and rice, these phytoglycogen‐accumulating mutants of barley lack isoamylase activity in the developing endosperm. The mutants were shown to be allelic, and...

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Published in:	The Plant journal : for cell and molecular biology Vol. 31; no. 1; pp. 97 - 112
Main Authors:	Burton, Rachel A., Jenner, Helen, Carrangis, Luke, Fahy, Brendan, Fincher, Geoffrey B., Hylton, Chris, Laurie, David A., Parker, Mary, Waite, Darren, Van Wegen, Sonja, Verhoeven, Tamara, Denyer, Kay
Format:	Journal Article
Language:	English
Published:	Oxford, UK Blackwell Science Ltd 01-07-2002 Blackwell Science
Subjects:	Alleles Amino Acid Sequence barley Base Sequence Biological and medical sciences Chromosome Mapping Cloning, Molecular DNA, Complementary - genetics DNA, Plant - genetics Fundamental and applied biological sciences. Psychology Genes, Plant Glucans - metabolism granules Hordeum - genetics Hordeum - growth & development Hordeum - metabolism Hordeum - ultrastructure initiation isoamylase Isoamylase - genetics Metabolism Microscopy, Electron Molecular Sequence Data Mutation Photosynthesis, respiration. Anabolism, catabolism phytoglycogen Plant physiology and development Plastids - metabolism starch Starch - metabolism Monocotyledones Hordeum vulgare Enzyme Starch Glycogen Deficiency Isoamylase Metabolism Cereal crop Starch granule Enzymatic activity Gramineae Ultrastructure Glycosidases Angiospermae Hydrolases Spermatophyta Endosperm Caryopsis Mutation Biological accumulation O-Glycosidases
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Summary:	Summary Two mutant lines of barley, Risø 17 and Notch‐2, were found to accumulate phytoglycogen in the grain. Like the sugary mutants of maize and rice, these phytoglycogen‐accumulating mutants of barley lack isoamylase activity in the developing endosperm. The mutants were shown to be allelic, and to have lesions in the isoamylase gene, isa1 that account for the absence of this enzyme. As well as causing a reduction in endosperm starch content, the mutations have a profound effect on the structure, number and timing of initiation of starch granules. There are no normal A‐type or B‐type granules in the mutants. The mutants have a greater number of starch granules per plastid than the wild‐type and, particularly in Risø 17, this leads to the appearance of compound starch granules. These results suggest that, as well as suppressing phytoglycogen synthesis, isoamylase in the wild‐type endosperm plays a role in determining the number, and hence the form, of starch granules.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0960-7412 1365-313X
DOI:	10.1046/j.1365-313X.2002.01339.x