Overexpression of a sorghum SnRK1βγ2 gene increases the biomass in Setaria viridis but not in rice

Abstract

Sorghum as a C₄ crop has been shown to be both drought tolerant and photosynthetically productive. In this study, we demonstrated that sorghum SbSnRK1βγ2(SbSNF4-2), the γ subunit of the sucrose non-fermenting 1 (SNF1)/SNF1-related protein kinase 1 (SnRK1) heterotrimeric complex, increased the plant height and biomass in Setaria viridis, a C4 relative of sorghum, but not in rice, a C3 relative, when overexpressed driven by the maize ubiquitin promoter. However, the overexpression did not increase the tiller number in S. viridis, although it caused modest increases in the tiller number in both sorghum and rice. In addition, SbSnRK1βγ2did not affect the panicle weight in sorghum, but its overexpression doubled the panicle weight in S. viridis in all four evaluated transgenic lines. Overall, the overexpression ofSbSnRK1βγ2 tripled the biomass production in S. viridis, indicating SbSnRK1βγ2’s potential in any future cellulosic biofuel production and S. viridis’ utility as an alternative genetic vehicle to functionally characterise sorghum genes.