show Abstracthide Abstractwe present an atlas of global gene expression as well as the evolutionary divergence covering embryo, endosperm and seed coat development in wheats and their diploid ancestors, providing insights into the evolution of gene expression in embryogenesis and grain development of wheat species. Overall design: We investigate the dynamics and evolution of gene expression throughout seven stages of embryo development (including the two cell, pre-embryo, transition, leaf early, leaf middle, leaf late and mature embryo), two stages of endosperm (transition stage endosperm and leaf late stage endosperm), and one pericarp stage (leaf early stage pericarp) across five wheat and ancestral grass species (AC -hexaploid, SF-tetraploid, DV-A genome diploid, SP-B genome diploid and TA-D genome diploid), two replicates for each stage.