8. Awn development

Barley exhibits a particularly diverse array of awn traits, including straight, hooded, crooked, triple, and leafy awns (Huang et al., 2021a). In botany, they are considered to be the extensions of the lemma tissue in cereal florets. They are highly active in photosynthesis and account for 30-50% of grain weight in barley. In addition to performing photosynthesis and contributing directly to grain yield, awns can also enhance seed dispersal during evolution and protect against pests and birds in farm production. However, the sharpness of awns can also pose challenges in harvesting and as green fodder. Non-awned varieties typically yield less, making short and hooded awns attractive alternatives that balance yield and practicality (Liao et al., 2025). Barley has a rich collection of natural and induced mutants in awn traits. Several genetic loci controlling awn traits have been cloned and their biological function been studied (Huang et al., 2021a; 2021b). We have recently identified a novel inverted hooded awn (IHA) trait and conducted bulked segregant analysis coupled with whole genome sequencing (BSA-seq) to investigate the inheritance of IHA, its genetic relationships with other awn traits. The Iha locus has been mapped to chromosome 3H, with close link with the Ari-a, and Sca1 loci. Gene cloning and functional study of the Iha locus is on-going (Huang et al., 2025). These findings have advanced our understanding of the complex genetic basis of awn development in barley and would facilitate development of new strategies in barley breeding programs aiming at selection of unique cultivars with diverse awn types.