Establishment of Growth Scale in Brachypodium distachyon

Brachypodium distachyon (Brachypodium) has become an emerging model plant for temperate grass plants. In almost all the model organisms, definition of growth scale throughout its lifecycle is an essential framework to describe and compare biological observations. Moreover, life cycle staging could be a powerful tool to provide appropriately staged material, which is vital for temporal phenotyping and omics analyses, such as transcriptomics and metabolomics, to unify the data among independent research projects as well as to integrate different bio- and information resources. Here, we propose a growth scale (BdZ scale) and image library for a universal staging framework in Brachypodium, which was emerged as a model system for studying biological systems of temperate grasses, including cereal crops such as wheat. To demonstrate the utility of our BdZ scale, we compared metabolome profiles based on simultaneous quantitative measurement of 517 metabolites at different growth stages between standard accession Bd21 and Bd3-1, as well as wheat cultivar Chinese Spring. The results efficiently elucidated the differences in the growth stages and also the difference between the species / accessions within defined morphological developmental stages. Our work should provide a conceptual framework for comparative analysis and for knowledge integration between this model grass and staple food crops such as wheat and barley.