Aktivitas Enzim Metabolisme Sukrosa dan Glikolisis pada Tanaman Padi Transgenik Overekspresi Gen SoSPS1

Abstract

Sucrose Phosphate Synthase (SPS) is a key enzyme in the sucrose biosynthesis pathway. Overexpression of the SPS gene has been reported to enhance sucrose accumulation and growth in various plant species. However, its effects on the dynamics of sucrose-metabolising and glycolytic enzymes in rice remain insufficiently explored. This study aimed to analyze the activities of sucrose metabolism enzymes, including SPS, invertases (acid and neutral), sucrose synthase (SuSy), and hexokinase (HXK) in transgenic rice plants overexpressing the SoSPS1 gene. The experiment was conducted using, four transgenic rice lines and wild type, T4, T6, T8, and T9, with four replicates. The results showed that overexpression of the SoSPS1 gene led to significant increases in plant height and biomass, as well as markedly enhanced SPS activity in all transgenic rice plants compared to the wild type. Invertase activity (A-INV and N-INV) did not differ significantly among genotypes. In contrast, SuSy activity increased significantly in transgenic lines T6, T8, and T9, suggesting that sucrose degradation in response to the genetic modification is primarily regulated through SuSy. The increase in SuSy activity was accompanied by increased HXK activity in the same lines (T6, T8, and T9), indicating that HXK subsequently phosphorylated hexose sugars produced from sucrose breakdown. Overall, this study demonstrates that overexpression of SoSPS1 influences carbon flux and sugar metabolism, providing deeper insights into the relationship among sucrose biosynthesis, sugar sensing, and biomass enhancement in transgenic rice.