Fig. 2
Ramified spike and turgidum-type of spike branching in tetraploid wheats. a, Illustration of structure of standard spike (WT) in T. durum LD222 (left), ramified spike (indicated as gradation from horizontal spikelets, HS, to ramified spike, RS) in T. durum R-107 (middle) and the turgidum-type of spike branching (indicated as branched head, BHt) in T. turgidum K-40750 (right). b, Schematic representation of the WFZP-A gene structures and the mutation identified. The light red box indicates the AP2/ERF domain. c-k, Scanning electron microscopy images of LD222 (WT), R-107 (bh) and K-40750 (bh t) inflorescences at various developmental stages. c and d, Spikelet differentiation stage in the wild type (c) and bh (d). e, Early floret differentiation stages when the spikelet meristem produces FMs in WT. f, Differentiation of secondary AxMs (indicated by asterisks) in the bh mutant. h and i, The development of glumes (gl*, indicated by arrows) and floret meristems (fm*s) by secondary AxMs in the bh and bh t mutants. g, Floret differentiation stage in the WT-inflorescence. h, development of an ectopic spikelet at place of a basal floret. j and k, Development of ectopic branch-like structures (b) in the bh and bh t mutants. Bars = 100 μm. f, floret with floret organ primordia; fm, floret meristem; gl, glume; im, inflorescence meristem; l, lemma, sm, spikelet meristem; sm*, spikelet meristem of an ectopic spikelet