The shape of an inflorescence varies among cereals, ranging from a highly branched panicle in rice to a much more compact spike in barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.). However, little is known about the molecular basis of cereal inflorescence architecture. We profiled transcriptomes at three developmental stages of the barley main shoot apex — spikelet initiation, floral organ differentiation, and floral organ growth — and compared them with those from vegetative seedling tissue. Transcript analyses identified 3688 genes differentially transcribed between the three meristem stages, with a further 1394 genes preferentially expressed in reproductive compared with vegetative tissue. Co-expression assembly and Gene Ontology analysis classified these 4888 genes into 28 clusters, revealing distinct patterns for genes such as transcription factors, histone modification, and cell-cycle progression specific for each stage of inflorescence development. We also compared expression patterns of VRS (SIX-ROWED SPIKE) genes and auxin-, gibberellic acid- and cytokinin-associated genes between two-rowed and six-rowed barley to describe regulators of lateral spikelet fertility. Our findings reveal barley inflorescence phase-specific gene expression, identify new candidate genes that regulate barley meristem activities and flower development, and provide a new genetic resource for further dissection of the molecular mechanisms of spike development.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We thank Yang Zhang (King Abdullah University of Science and Technology, Saudi Arabia) for collecting materials, Jie Zong (Shanghai Jiao Tong University, China) for providing guidance in genome analysis, and Natalie Betts (The University of Adelaide) for valuable comments and for revision of the article. This work was supported by Australian Research Council (DP170103352); an Australia-China Science and Research Fund Joint Research Centre grant ACSRF48187; Start-up funding (Australia, 13114779, 62117250) for Dabing Zhang from the School of Agriculture, Food and Wine, The University of Adelaide; and the Innovative Research Team, Ministry of Education of China; the 111 Project (B14016).