The AkCSLA3-AkMSR1 module mediates Konjac glucomannan biosynthesis in Amorphophallus konjac

Background Konjac glucomannan (KGM) is a high-viscosity, water-soluble dietary fiber that accumulates predominantly in the corms of Amorphophallus konjac ( A. konjac ). Due to its excellent gel-forming and water-retention properties, KGM is widely used in the food industry. The biosynthesis of KGM involves the coordinated action of cellulose synthase-like (CSL) enzymes and mannan synthesis-related (MSR) proteins. However, the regulatory mechanisms and functional interactions between these components remain poorly understood in A. konjac. Results In this study, we systematically characterized the AkCSLA gene family in A. konjac and identified 11 family members. Transcriptomic analysis revealed that AkCSLA2 and AkCSLA3 were highly expressed during the corm expansion and maturation stages, which correspond to the periods of active KGM accumulation. Subcellular localization assays in Nicotiana benthamiana showed that both AkCSLA2 and AkCSLA3 proteins localized to the plasma membrane, endoplasmic reticulum, and Golgi apparatus. Protein interaction analyses using yeast two-hybrid and co-immunoprecipitation assays demonstrated that AkMSR1, a homologue of Arabidopsis MSR1, specifically interacted with AkCSLA3, but not with AkCSLA2. Functional studies in Pichia pastoris revealed that co-expression of AkCSLA3 and AkMSR1 significantly increased the production of mannose and glucose, with mannose content elevated more than threefold compared to expression of AkCSLA3 alone. Conclusion This study identifies the AkCSLA3-AkMSR1 module as a crucial regulatory mechanism in KGM biosynthesis, wherein AkMSR1 acts as a specific cofactor to enhance the glucomannan synthesis mediated by AkCSLA3. This research provides novel insights into the molecular regulation of KGM biosynthesis and presents potential targets for the genetic enhancement of KGM content in A. konjac.