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GrainGenes Reference Report: TPJ-31-97

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Reference	TPJ-31-97
Title	Starch granule initiation and growth are altered in barley mutants that lack isoamylase activity
Journal	Plant Journal
Year	2002
Volume	31
Pages	97-112
Author	Burton RA [ Show all 12 ]
Abstract	Summary: Two mutant lines of barley, Riso 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 Riso 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
Gene	Isa1 (Hordeum)
Keyword	[ Hide all but 1 of 36 ] a-type adp glucose amylopectin biosynthesis amyloplasts appearance b-type barley barley mutant biogenesis debranching enzyme endosperm endosperm starch enzyme gene glycogen granule growth isoamylase lead leads lesions maize mutant mutant lines phytoglycogen plastid reduction rice rice endosperm starch starch granule starches structure synthase synthesis wild-type

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