Chain Length Distribution of Amylopectins of Double‐ and Triple‐Mutants Containing the Waxy Gene in the Inbred Oh43 Maize Background

Abstract

Abstract Starch granules were isolated from mature kernels of double‐ and triple‐mutant combinations of the waxy ( w x ) gene with other starchmodifying genes in the inbred Oh43 maize background. The amylose content and the distribution of unit chain‐length of amylopectin were determined by enzymatic‐chromatographic methods. Starches of the mutants containing the wx gene comprised 100% amylopectin. Amylopectin of the amylose‐extender;waxy ( ae wx ) mutant had an increased proportion of long B chains and decreased proportion of short B chains, compared with wx amylopectin, whereas amylopectin of the dull;waxy ( du wx ) mutant had a decreased proportion of long B chains and an increased proportion of short B chains. Therefore, the ae wx and du wx mutants amylopectins were novel. The A:B chain ratios for amylopectins examined, namely for ae wx , amylose‐extender;waxy;floury‐2 ( ae wx fl 2 ), amylose‐extender;waxy;sugary‐1 ( ae wx su 1 ), amylose‐extender;waxy;sugary‐2 ( ae wx su 2 ), brittle‐1;waxy ( bt 1 wx ). dull;waxy ( du wx ), and sugary‐2;waxy ( su 2 wx ) amylopectins, were in a range of 1.1 to 1.4 and similar to the wx amylopectin. Thus, starches of double‐mutant combinations of the wx gene with other starch‐modifying genes are good sources for elucidating the fine structure of amylopectin, in regards to long‐ and short‐B chains, which is affected by a single recessive gene coupled with the wx gene.