遺伝的要因が澱粉の特性に及ぼす影響

Abstract

1. Starch granules were prepared from mature kernels of several single mutants, double- and triple-mutant combinations of waxy (wx) gene with other endosperm genes, and their normal counterpart in the inbred 0h43 maize (Zea mays L.) background. Starches of the mutants containing the wx gene comprised almost 100% amylopectin. jS-Amylase limit dextrins prepared from the starches were successively debranched by isoamylase and pullulanase, and followed by quantitative gel-filtration on Toyopearl HW54SF. The unit chain-length distribution of amylopectins of the normal and wx starches were similar. Amylopectin of the amylose-extender ; waxy (ae ; wx) mutant had an increased proportion of long B chains and a decreased proportion of short B chains, compared with wx amylopectin, whereas amylopectin of 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 amylopectins were novel. Amylopectin of the ae ; du; wx mutant belonged to the du ; wx type instead of the ae ; wx type. 2. Starch granules were prepared from rice (Oryza sativa L.) endosperms of dull (du), sugary (sug), and high-amylose (ae) mutants. The amylose content of the du starch was half as low as that of the nonmutant (normal) one. The sug starch contained more amylose than the normal starch. The starch in the ae mutants was characterized by a higher content of amylose and loosely branched amylopectin with longer chains compared with the normal starch.