Phenological growth stages according to the BBCH-scale as a powerful tool for differentiating among CRISPR/Cas9 mutated lineages of the model plant Setaria viridis (L.) P. Beauv. (Poaceae)

In recent years, Setaria viridis (L.) P. Beauv. has increased its popularity as a model plant for genetic studies with C4 monocotyledons. The BBCH-scale comprises a detailed phenotypic analysis, based on predefined growth stages, allowing for the construction of a comprehensive tool for morphological studies. We constructed a BBCH-scale for the ME034V wild-type accession and compared it with two independent mutants of the LONESOME HIGHWAY (LWH), which did not have noticeable morphological phenotypes. Our analysis showed that the main growth stages (0, 1, 2, and 7) showed homogeneity between the wild accession and the mutants. However, developmental changes between accessions were observable by comparing the secondaries of these main stages. There were significant differences between the wild accession and the mutants in relation to the main stages 4, 5, and 9. The total life cycle was reduced by 5 days in the svlhw-1 mutant. With a short life cycle like Setaria viridis, the observed changes can probably be attributed to genetic factors since the environmental conditions were strictly controlled. Thus, we showed that the BBCH-scale offers a powerful system to discriminate between Setaria viridis mutants that would otherwise be indistinguishable.