Characterization of Starch Granules from Waxy, Nonwaxy, and Hybrid Seeds of Amaranthus hypochondriacus L.

Abstract

Perisperm starch granules of the dicotyledonous plant Amaranthus hypochondriacus L. were prepared from two homozygous lines (WxWx and wxwx) and their hybrid (Wxwx). The hybrid line was obtained by natural hybridization. By Sephadex G-75 column chromatography of isoamylase-debranched starches, the amylose content of WxWx starch was 16.9%, that of Wxwx was 10.7, and wxwx was zero. SDS-polyacrylamide gel electrophoresis showed that starch granules from two genotypes (WxWx and Wxwx) contained a Wx protein (MW = 68,000) which was supposed to be a starch granule-bound starch synthase and was associated with amylose synthesis, as observed in nonwaxy maize. The intensities of the stained protein bands were apparently correlated with the number of the Wx alleles. The Wx protein was not detected in the wxwx starch. These findings suggest that the Wx allele produces the Wx protein and amylose in the perisperm of A. hypochondriacus, with incomplete dominance over the wx allele. The Wx allele did not affect the fine structure of amylopectin and had little if any effect on susceptibility to glucoamylase and pasting properties of starch granules from these genotypes.