This study identifies *GC1* (Glume Coverage 1), encoding an atypical G protein γ subunit, as a major gene negatively regulating sorghum glume coverage. Naturally truncated *GC1* variations accumulate at higher protein levels, affecting patatin-related phospholipase SbpPLAII-1 stability. A strong positive selection signature around *GC1* is found in naked sorghum cultivars. The findings reveal a crucial domestication event via subtle glume development regulation by *GC1* C-terminus variation, establishing a strategy for future naked grain breeding.
