A set of domain-specific markers in the Arabidopsis embryo

We describe a novel set of domain-specific markers that can be used in genetic studies, and we used two examples to show loss of stem cells in a monopteros background. Multicellular organisms can be defined by their ability to establish distinct cell identities, and it is therefore of critical importance to distinguish cell types. One step that leads to cell identity specification is activation of unique sets of transcripts. This property is often exploited in order to infer cell identity; the availability of good domain-specific marker lines is, however, poor in the Arabidopsis embryo. Here we describe a novel set of domain-specific marker lines that can be used in Arabidopsis (embryo) research. Based on transcriptomic data, we selected 12 genes for expression analysis, and according to the observed expression domain during embryogenesis, we divided them into four categories (1-ground tissue; 2-root stem cell; 3-shoot apical meristem; 4-post-embryonic). We additionally show the use of two markers from the "stem cell" category in a genetic study, where we use the absence of the markers to infer developmental defects in the monopteros mutant background. Finally, in order to judge whether the established marker lines also play a role in normal development, we generated loss-of-function resources. None of the analyzed T-DNA insertion, artificial microRNA, or misexpression lines showed any apparent phenotypic difference from wild type, indicating that these genes are not nonredundantly required for development, but also suggesting that marker activation can be considered an output of the patterning process. This set of domain-specific marker lines is therefore a valuable addition to the currently available markers and will help to move toward a generic set of tissue identity markers.