The genetics of inflorescence architecture in Hordeum

The barley (Hordeum vulgare) spike exists in two alternative forms: six‐rowed or two rowed. The genetic basis of this difference lies in the single gene Vrs1, the recessive allele of which is responsible for the six‐rowed phenotype. The gene encodes a homeodomain‐leucine zipper I class transcription factor. Its paralog HvHox2 is well conserved among the cereals, whereas Vrs1 acquired its…