Structural analysis of starch from normal and shx (shrunken endosperm) barley (Hordeum vulgare L.)

The shx shrunken endosperm mutation of barley is the only one described with its primary effect on Type I, primer-independent soluble starch synthase (SSS). The mutant produces grains with only 31% of the normal dry weight of starch, associated with a decrease in A-granule dimensions. We investigated the structure of shx and normal cv. Bomi barley amylose and amylopectin. Surprisingly, both amylose and amylopectin from the two genotypes were very similar in all aspects examined. These findings are discussed in the light of the potential roles for the various forms of SSS and branching enzyme.