Amylose content is not affected by overexpression of the Wx-B1 gene in durum wheat

With 6 figures and 1 table Abstract The granule-bound starch synthase (GBSS), known as waxy protein, is the sole enzyme responsible for amylose synthesis, whereas amylopectin is produced by concerted action of several isoforms, including starch synthases, branching and debranching enzymes. Durum wheat contains two waxy genes, which encode the Wx-A1 and Wx-B1 proteins, respectively. In order to investigate the effect of the overexpression of the waxy genes on amylose content and starch properties, durum wheat transgenic lines overexpressing the Wx-B1 gene were produced. Amylose content of the transgenic lines did not show any increase compared to the untransformed cultivar. One of the transgenic lines was crossed with a mutant waxy genotype of durum wheat lacking all the waxy protein isoforms. The screening of F2 segregant plants permitted the identification of lines possessing various combinations of waxy genes, including the line containing only the construct used in the transformation. In this line, the normal vitreous seed phenotype, because of the presence of amylose, was restored confirming a correct functioning of the transgene.