Organ-enriched gene expression during floral morphogenesis in wild barley.

Floral morphology varies considerably between dicots and monocots. The ABCDE model explaining how floral organ development is controlled was formulated using core eudicots and applied to grass crops. Barley (Hordeum. vulgare) has unique floral morphogenesis. Wild barley (H. vulgare ssp. spontaneum), which is the immediate ancestor of cultivated barley (H. vulgare ssp. vulgare), contains a rich reservoir of genetic diversity. However, the wild barley genes involved in floral organ development are still relatively uncharacterized. In this study, we generated an organ-specific transcriptome atlas for wild barley floral organs. Genome-wide transcription profiles indicated that 22 838 protein-coding genes were expressed in at least one organ. These genes were grouped into seven clusters according to the similarities in their expression patterns. Moreover, 5619 genes exhibited organ-enriched expression, 677 of which were members of 47 transcription factor families. Gene ontology analyses suggested that the functions of the genes with organ-enriched expression influence the biological processes in floral organs. The co-expression regulatory network showed that the expression of 690 genes targeted by MADS-box proteins was highly positively correlated with the expression of ABCDE model genes during floral morphogenesis. Furthermore, the expression of 138 genes was specific to the wild barley OUH602 genome and not the Morex genome; most of these genes were highly expressed in the glume, awn, lemma, and palea. This study revealed the global gene expression patterns underlying floral morphogenesis in wild barley. On the basis of the study findings, a molecular mechanism controlling floral morphology in barley was proposed.