An Overview of Sucrose Synthases in Plants

Abstract

Sucrose is the end product of photosynthesis and the primary sugar transported in the phloem of most plants. Sucrose synthase (SuSy) is a glycosyl transferase enzyme that plays a key role in sugar metabolism, primarily in sink tissues. SuSy catalyzes the reversible cleavage of sucrose into fructose and either uridine diphosphate glucose (UDP-G) or adenosine diphosphate glucose (ADP-G). The products of sucrose cleavage by SuSy are available for many metabolic pathways, such as energy production, primary-metabolite production, and the synthesis of complex carbohydrates. SuSy proteins are usually homotetramers with an average monomeric molecular weight of about 90 kD (about 800 amino acids long). Plant SuSy isozymes are mainly located in the cytosol or adjacent to plasma membrane, but some SuSy proteins are found in the cell wall, vacuoles, and mitochondria. Plant SUS gene families are usually small, containing between four to seven genes, with distinct exon-intron structures. Plant SUS genes are divided into three separate clades, which are present in both monocots and dicots. A comprehensive phylogenetic analysis indicates that a first SUS duplication event may have occurred before the divergence of the gymnosperms and angiosperms and a second duplication event probably occurred in a common angiosperm ancestor, leading to the existence of all three clades in both monocots and dicots. Plants with reduced SuSy activity have been shown to have reduced growth, reduced starch, cellulose or callose synthesis, reduced tolerance to anaerobic-stress conditions and altered shoot apical meristem function and leaf morphology. Plants overexpressing SUS have shown increased growth, increased xylem area and xylem cell-wall width, and increased cellulose and starch contents, making SUS high-potential candidate genes for the improvement of agricultural traits in crop plants. This review summarizes the current knowledge regarding plant SuSy, including newly discovered possible developmental roles for SuSy in meristem functioning that involve sugar and hormonal signaling.

Acid invertase confers heat tolerance in rice plants by maintaining energy homoeostasis of spikelets

“…Thus, different functions in affecting heat tolerance might exist between sucrose synthase and acid invertase in rice plants. Sucrose synthase is a glycosyl transferase and reversibly converts sucrose in the presence of UDP into UDP‐glucose and fructose (Stein & Granot, ). In contrast, invertase is a hydrolase that irreversibly hydrolyses sucrose into glucose and fructose (Roitsch & Gonzalez, ).…”

Plant Cell Walls Tackling Climate Change: Biotechnological Strategies to Improve Crop Adaptations and Photosynthesis in Response to Global Warming

“…Nucleotide sugars, such as uridine diphosphate glucose (UDP-Glc), constitute the precursors for synthesis of CW polysaccharides [35]. Metabolic pathways of sucrose catabolism and provision of UDP-Glc for CW have been well reported [36][37][38]. CW synthesis requires sucrose as the source of C and energy ( Figure 2).…”

Spatiotemporal shading regulates anthocyanin, proanthocyanidin, and sucrose accumulation in black soybean seeds

“…Abiotic stress has been reported to affect sucrose translocation due to an impaired photosynthesis process and reductions in the associated enzymes (Bellaloui, 2012). Previous studies have also reported that, under stress conditions in soybean, the sucrose synthase enzyme decline severalfold (Stein & Granot, 2019).…”