Identification and characterization of a novel Wx-B1 allele in a waxy wheat (Triticum aestivum L.)

The composition of starch, which includes amylose and amylopectin, greatly affects the quality and characteristics of flour. The balance between these components is crucial in determining the properties and structure of starch. The waxy (Wx) gene encodes granule-bound starch synthase I (GBSSI), which is responsible for amylose biosynthesis in the endosperm. Gunji-3 was created through a cross between the waxy-type wheat cultivar Shinmichal 1 and the bread wheat cultivar Keumkang. Upon comparing the Wx-B1 allele encoding GBSSI in Gunji-3 with the Wx-B1 allele in Shinmichal 1 and Wx-B1b, a total of four SNPs and one deletion were identified in Gunji-3. Additionally, when comparing amino acid sequences with Wx-B1 alleles, differences at three positions were found, indicating that the mutant carried a new Wx-B1 allele named Wx-B1o. The physicochemical properties of Gunji-3 starch were characterized by a lower amylose content of 2.30% compared to 7.45% in Shinmichal 1 and 27.67% in Keumkang. Additionally, it exhibited a higher water retention capacity of 84.66% compared to 75.91% in Shinmichal 1 and 66.07% in Keumkang. The newly introduced waxy-type wheat could provide an essential basis for understanding wheat's starch characteristics and various breeding programs.