Tilling of the gene HvHox1 reveals new alleles of the two-rowed/six-rowed locus Vrs1. (A) Model of the gene HvHox1 (Vrs1) designed from output files of the software PARSESNP . Gene structure and distribution as well the type of mutation discovered in a 1,270-bp region covering the entire open reading frame (ORF) of the gene are illustrated: exons = red open boxes, introns = red lines, conserved homeodomain-leucine zipper I-class homeobox domain (obtained from the BLOCKS database, ) = green boxes above the gene structure model. Mutations are indicated as small arrowheads below the gene structure model: purple = non-functional mutations, i.e., intron-located or synonymous mutations; black = non-synonymous mutations; and red = a splice junction mutation. Numbered arrowheads indicate mutations leading to phenotypic changes in M2 individuals 11910-1 (1), 3930-1 (2), 8408-1 (3), and 11657-1 (4), respectively. Detailed views of total inflorescences (B-E) and lateral spikelet morphology (F-I) are given for wild-type (two-rowed) 'Barke' (B, F), a six-rowed (hex-v) mutant (8408-1) (C, G), an Intermedium spike-d (Int-d) mutant (11657-1) (D, H), and mutant 3930-1 (E, I). Mutant 8408-1 possessed fully fertile and awned lateral spikelets (G), whereas the lateral spikelets of mutant 11657-1 exhibited shorter awns and only partial fertility, mostly in the basal lateral spikelets (H). The lateral spikelets of 3930-1 were significantly enlarged and tip-pointed compared to 'Barke,' but were sterile and not awned (I).