Spatial transcriptomics identifies distinct domains regulating yield-component traits of the wheat ear

Cereals form complex, highly ordered inflorescences composed of grain-producing florets that form within spikelets. Wheat spikelets are arranged in alternating rows along a central rachis, in a pattern determined during early development. While several genes controlling spikelet formation have been identified, it is still unclear how they interact to regulate inflorescence morphology and the development of supporting structures, including meristems and the rachis. Here, we used spatial transcriptomics to investigate the transcriptional landscape of a developing wheat inflorescence. We identified two spatially distinct regions that regulate spikelet architecture, including a primordium region characterized by <i>RAMOSA2</i> and a boundary region that expresses <i>ALOG1</i> and bract suppressors. Developmental assays indicate that spikelets differentiate from meristems and are accompanied by formation of the central vasculature that expresses spikelet number and fertility genes. The combined spatial transcriptome and genetic data reveal key regulators of spikelet development, including target genes for improving spikelet number and yield.