A domestication gene links plant architecture and nitrogen metabolism to enhance yield in foxtail millet.
basic_science · Level V
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- Record sourced from PubMed, PMID 42321213.
- Also identified by DOI 10.1038/s41467-026-74682-w.
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Abstract
Foxtail millet (Setaria italica) has lagged in yield compared with major cereals, largely due to suboptimal architecture. Here, we report a telomere-to-telomere (T2T) genome assembly of the dwarf, multi-tillering cultivar Dungu and identify SiSD1 (Semi Dwarf 1) via map-based cloning. This gene encodes GA20ox2, the rice SD1 ortholog involved in gibberellin biosynthesis. The loss-of-function sisd1 reduces bioactive gibberellins and remodels nitrogen metabolism, conferring semi-dwarfism, increased tillering, and higher yield. Critically, the semi-dominantly heterozygous SiSD1/sisd1 in F<sub>1</sub> hybrids optimally balances stature, tillering, and nitrogen acquisition to drive yield heterosis. Genotype surveys confirm the prevalence of this allele in elite commercial hybrids, including the high-yield hybrid Zhangzagu series. Mechanistically, the SiSLR1-SiERF7/073 module precisely regulates SiSD1 transcription. D157E substitution in SiSD1 relative to its wild progenitor attenuates GA biosynthesis and has been favored during domestication. Collectively, SiSD1 functions as a pleiotropic integrator of development and nitrogen physiology, and deployment of its heterozygosity offers a targeted breeding strategy for crop improvement.