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 describe d with its primary effect on Type I, primer-independent soluble starch synthase (SSS). The mutant produces grains with only 31% of the norma l dry weight of starch, associated with a decrease in A-granule dimens ions. We investigated the structure of shx and normal cv. Bomi barley amylose and amylopectin. Surprisingly, both amylose and amylopectin fr om the two genotypes were very similar in all aspects examined. These findings are discussed in the light of the potential roles for the var ious forms of SSS and branching enzyme.