Mini foxtail millet as a new C4 model species (Nat. Plants) ($)

The three most widely adopted plant models all use C3 photosynthesis, but discoveries made in these plants are not always applicable to C­4 plants. Foxtail millet (Setaria italica) has been emerging as a potential C4 model species, but its use for genomics research is challenging due to long generation time and recalcitrance to genetic transformation. Through a large-scale mutagenesis screen, Yang et al. have characterized a mini rapid-cycling mutant of foxtail millet -named xiaomi – as a promising new model system for C­4 plants. xiaomi mutants harbour a point mutation in the Phytochrome C (PHYC) gene leading to a premature stop codon and impairing the essential function of this light receptor in photoperiodic flowering. The small stature and fast life cycle of xiaomi enables completion of 5-6 generations within one year and with similar space requirements to the equivalent amount of Arabidopsis. The authors assembled and annotated a high-quality reference genome for xiaomi and an online dynamic gene expression atlas. Finally, they established an efficient Agrobacterium-mediated genetic transformation system using embryonic calli. Future research with xiaomi could help investigate many characteristics of C4 plants for improvement of agricultural species. (Summary by Katy Dunning @plantmomkaty) Nature Plants 10.1038/s41477-020-0747-7