Engineering High-Amylose and High-Dietary-Fibre Barley Grains Through Multiplex Genome Editing of Four Starch-Synthetic Genes

Barley, rich in beneficial ingredients, has been recognised as a healthy food and is widely used in the production of healthy foods for humans. The current study identified a new barley mutant with the <i>SSIIa</i>, <i>SSIIIa</i>, <i>SBEIIa</i>, and <i>SBEIIb</i> genes inactivated in the genome-edited offspring of targeted mutagenesis of starch synthetic genes using multiplex genome editing. The grain compositions and starch properties of the <i>ssIIa/ssIIIa/sbeIIa/sbeIIb</i> mutant were analysed and compared with the corresponding parameters of <i>ssIIa</i>, <i>ssIIIa</i>, <i>sbeIIa/sbeIIb</i>, <i>ssIIa/sbeIIa/sbeIIb</i>, and non-genome-edited lines (NE), respectively. <i>ssIIa/ssIIIa/sbeIIa/sbeIIb</i> exhibited the highest contents of β-glucan and amylose content among all mutants and NE, but not the most prominent in resistant starch, fructan, and fibre contents. The loss of <i>SSIIa</i>, <i>SSIIIa</i>, <i>SBEIIa</i>, and <i>SBEIIb</i> genes also resulted in significant changes in starch properties. This study enriched the genotypes of healthy barley and provided a theoretical basis for improving barley quality.