Understanding starch biosynthesis in potatoes for metabolic engineering to improve starch quality: A detailed review

Potato tubers accumulate substantial quantities of starch, which serves as their primary energy reserve. As the predominant component of potato tubers, starch strongly influences tuber yield, processing quality, and nutritional attributes. Potato starch is distinguished from other food starches by its unique granule morphology and compositional attributes. It possesses large, oval granules with amylose content ranging from 20 to 33 % and high phosphorus levels, which collectively determine the unique physicochemical characteristics. These physicochemical properties direct the utility of potato starch across diverse food and industrial applications. This review synthesizes current knowledge on the molecular factors controlling potato starch biosynthesis and structure-function relationships. Key topics covered are starch granule morphology, the roles and regulation of major biosynthetic enzymes, transcriptional and hormonal control, genetic engineering strategies, and opportunities to tailor starch functionality. Elucidating the contributions of different enzymes in starch biosynthesis has enabled targeted modification of potato starch composition and properties. However, realizing the full potential of this knowledge faces challenges in optimizing starch quality without compromising plant vigor and yield. Overall, integrating multi-omics datasets with advanced genetic and metabolic engineering tools can facilitate the development of elite cultivars with enhanced starch yield and tailored functionalities.