A Novel Isoform of Sucrose Synthase Is Targeted to the Cell Wall during Secondary Cell Wall Synthesis in Cotton Fiber    

Abstract

Sucrose (Suc) synthase (Sus) is the major enzyme of Suc breakdown for cellulose biosynthesis in cotton (Gossypium hirsutum) fiber, an important source of fiber for the textile industry. This study examines the tissue-specific expression, relative abundance, and temporal expression of various Sus transcripts and proteins present in cotton. A novel isoform of Sus (SusC) is identified that is expressed at high levels during secondary cell wall synthesis in fiber and is present in the cell wall fraction. The phylogenetic relationships of the deduced amino acid sequences indicate two ancestral groups of Sus proteins predating the divergence of monocots and dicots and that SusC sequences form a distinct branch in the phylogeny within the dicotspecific clade. The subcellular location of the Sus isoforms is determined, and it is proposed that cell wall-localized SusC may provide UDP-glucose for cellulose and callose synthesis from extracellular sugars.

Critical Roles of Vacuolar Invertase in Floral Organ Development and Male and Female Fertilities Are Revealed through Characterization of GhVIN1-RNAi Cotton Plants

“…Prior to its use for metabolism and biosynthesis, Suc needs to be degraded into hexoses by either Suc synthase (Sus; EC 2.4.1.13) or invertase (INV; EC 3.2.1.26). Sus cleaves Suc in the presence of UDP into UDP-Glc and Fru and is largely involved in cell wall and starch biosynthesis in sink organs (Brill et al, 2011) and maintaining sink strength (Pozueta-Romero et al, 1999;Xu et al, 2012), especially in crop species (Ruan, 2014). INV, on the other hand, hydrolyzes Suc into Fru and Glc and plays essential roles in plant development and stress responses (Koch, 2004;Ruan, 2014).…”

New Insights into Roles of Cell Wall Invertase in Early Seed Development Revealed by Comprehensive Spatial and Temporal Expression Patterns of GhCWIN1 in Cotton

“…Prior to its use for metabolism and biosynthesis, Suc must be degraded into hexoses, by either Suc synthase (Sus; EC 2.4.1.13) or invertase (b-fructosidase; EC 3.2.1.26). Sus cleaves Suc into UDP-Glc and Fru and is largely involved in cell wall and starch biosynthesis (Chourey et al, 1998;Brill et al, 2011) and maintaining sink strength (Pozueta-Romero et al, 1999;Xu et al, 2012). Invertase, on the other hand, irreversibly hydrolyzes Suc into Fru and Glc and plays vital roles in plant development and stress responses Li et al, 2012).…”

Characterization of <italic>in vivo</italic> phosphorylation modification of differentially accumulated proteins in cotton fiber-initiation process

“…However, the detailed molecular mechanism of the transporting process is still unclear [22]. Here, we found that the threonine 27 of sucrose synthase 1 precursor protein is phosphorylated in initiating cotton fiber cells ( Table 1).…”