Use of advanced recombinant lines to study the impact and potential of mutations affecting starch synthesis in barley.

The effects on barley starch and grain properties of four starch synthesis mutations were studied during the introgression of the mutations from diverse backgrounds into an elite variety. The (ADPglucose transporter), (granule-bound starch synthase), (debranching enzyme isoamylase 1) and (starch synthase IIa) mutations were introgressed into NFC Tipple to give mutant and wild-type BCF families with different genomic contributions of the donor parent. Comparison of starch and grain properties between the donor parents, the BCF families and NFC Tipple allowed the effects of the mutations to be distinguished from genetic background effects. The and mutations had marked effects on starch properties regardless of genetic background. The mutation conditioned low grain weight and starch content, but the mutation did not. The mutation conditioned low grain weight and starch content, but exceptionally high β-glucan contents. The 1 mutation promotes synthesis of soluble α-glucan (phytoglycogen). Its introgression into NFC Tipple increased grain weight and total α-glucan content relative to the donor parent, but reduced the ratio of phytoglycogen to starch. This study shows that introgression of mutations into a common, commercial background provides new insights that could not be gained from the donor parent.