INTERMEDIUM-M encodes an HvAP2L-H5 ortholog and is required for inflorescence indeterminacy and spikelet determinacy in barley

Inflorescence architecture dictates the number of flowers and hence seeds. The architectural differences between two related cereals barley and wheat are controlled by differences in determinacy of inflorescence and spikelet meristems. Here, we characterize two allelic series of mutations named intermedium-m (int-m) and double seed1 (dub1) that convert barley indeterminate inflorescences into wheat-like determinate inflorescences bearing a multi-floreted terminal spikelet and indeterminate spikelets with additional florets. We collected mRNA from developing spikes from the double ridge (DR), triple-mound-spikelet meristem (TM-SM), floret meristem (FM, a.k.a lemma primordium), stamen primordium (StP) and awn primordium (AP) stages. We then used the RNA-sequencing (RNA-seq) to sequence the mRNA samples for both variants calling for introgression mapping and differential gene expression analysis between the wildtype Bowman and two int-m Near-isogenic lines (NIL).