Biomass yield is one of the important traits of sorghum, which is greatly affected by leaf morphology. In this study, a lobed-leaf mutant (sblob) was screened and identified, and its F2 inbred segregating line was constructed. Subsequently, MutMap and whole-genome sequencing were employed to identify the candidate gene (sblob1), the locus of which is Sobic.003G010300. Pfam and homologous analysis indicated that sblob1 encodes a Cytochrome P450 protein and plays a crucial role in the plant serotonin/melatonin biosynthesis pathway. Structural and functional changes in the sblob1 protein were elucidated. Hormone measurements revealed that sblob1 regulates both leaf morphology and sorghum biomass through regulation of the melatonin metabolic pathway. These findings provide valuable insights for further research and the enhancement of breeding programs, emphasizing the potential to optimize biomass yield in sorghum cultivation.

Foxtail millet (Setaria italica L.) is an important food crop worldwide and serves as a model for studying C4 photosynthesis and drought resistance. However, its application in functional genomics and molecular breeding has been severely constrained by the absence of a reliable genetic transformation system. In this study, 66 varieties were systematically evaluated for embryogenic callus induction capacity, with rates ranging from 0 to 70.22%. Among these, five varieties exhibited high embryogenic potential (>50%). Jingu51, an elite cultivated variety in northern China, was selected as the transformation recipient due to its rapid embryogenic response and high induction frequency. Optimization of culture conditions revealed that Murashige & Skoog (MS) medium supplemented with 30 g·L⁻¹ sucrose, 3 g·L⁻¹ phytagel, 1 mg·L⁻¹ CuSO₄, and 1 mg·L⁻¹ 2,4-dichlorophenoxyacetic acid combined with 0.5 mg·L⁻¹ 6-benzylamino purine was optimal for embryogenic callus induction. Key parameters of Agrobacterium-mediated transformation, including 100 μM acetosyringone concentration, callus pretreatment (heat shock, followed by ice bath), bacterial density (OD₆₀₀ = 0.3), and cocultivation temperature (19 °C), were optimized. Under these conditions, a robust genetic transformation system was successfully established, yielding an average efficiency of 9.25% by PCR across multiple expression vectors; half transgenic event exhibited single copy. Notably, the genetic transformation system of Jingu51, an elite variety of foxtail millet, provided a robust platform for functional genomics research and accelerated molecular breeding efforts in this important crop.