Breeding low-glycemic index barley for functional food

•Naked (hull-less) barley lines with lower GI values than oats were selected for UK agronomy from large segregating bulks.•The naked lines are a valuable resource for breeding and product testing for commercial supply chain development for food barley.•A QTL for β glucan content associated with the CslF6 gene (but not associated with nud) can be targeted in marker assisted selection. Low glycemic index (GI) grains with high levels of β glucan soluble fibre are beneficial for health. Naked barley (Hordeum vulgare L.) cultivars generally have higher grain β glucan contents than hulled barley, but lower yields. Naked grain requires no pearling or processing for use in wholegrain health foods and it is widely recognised that consumption of wholegrain barley is beneficial for health. Nearly all commercially available UK barley cultivars are hulled and have been bred for low (