Tissue-specific transcriptome analysis within the maturing sugarcane stalk reveals spatial regulation in the expression of cellulose synthase and sucrose transporter gene families

Abstract

Sugarcane (Saccharum spp. hybrids) accumulates high concentrations of sucrose in its mature stalk and a considerable portion of carbohydrate metabolism is also devoted to cell wall synthesis and fibre production. We examined tissue-specific expression patterns to explore the spatial deployment of pathways responsible for sucrose accumulation and fibre synthesis within the stalk. We performed expression profiling of storage parenchyma, vascular bundles and rind dissected from a maturing stalk internode of sugarcane, identifying ten cellulose synthase subunit genes and examining significant differences in the expression of their corresponding transcripts and those of several sugar transporters. These were correlated with differential expression patterns for transcripts of genes encoding COBRA-like proteins and other cell wall metabolism-related proteins. The sugar transporters genes ShPST2a, ShPST2b and ShSUT4 were significantly up-regulated in storage parenchyma while ShSUT1 was up-regulated in vascular bundles. Two co-ordinately expressed groups of cell wall related transcripts were also identified. One group, associated with primary cell wall synthesis (ShCesA1, ShCesA7, ShCesA9 and Shbk2l3), was up-regulated in parenchyma. The other group, associated with secondary cell wall synthesis (ShCesA10, ShCesA11, ShCesA12 and Shbk-2), was up-regulated in rind. In transformed sugarcane plants, the ShCesA7 promoter conferred stable expression of green fluorescent protein preferentially in the storage parenchyma of the maturing stalk internode. Our results indicate that there is spatial separation for elevated expression of these important targets in both sucrose accumulation and cell wall synthesis, allowing for increased clarity in our understanding of sucrose transport and fibre synthesis in sugarcane.

Allele-defined genome of the autopolyploid sugarcane Saccharum spontaneum L.

“…In sugarcane and sweet sorghum, the stems are the principal sink tissues that store very high concentrations of sugars within the parenchyma cells [42][43][44] . Tonoplast sugar transporters (TSTs) have been characterized as sucrose transporters highly associated with vacuolar sucrose accumulation from sugar beet taproot 45 , sugarcane 46 and sweet sorghum stems 47 and watermelon fruit 48 . Whereas there are 3 TST genes in the sorghum genome 47 , the family has expanded in the S. spontaneum genome, which has 4 genes consisting of 13 homologs.…”

Expression of sugarcane genes associated with perception of photoperiod and floral induction reveals cycling over a 24-hour period

“…All genes amplified in this study have been labelled after the form Saccharum hybrid (Sh), although commercial sugarcane varieties are hybrids between two species, so it is possible that some sequences are derived from Saccharum spontaneum and others from Saccharum officinarum. The housekeeping gene used to normalise the qPCR was ACTIN DEPOLYMERISING FACTOR (ADF, Casu et al 2015). Primer sequences for all genes are detailed in Table S1.…”

Glycoside Hydrolases in Plant Cell Wall Proteomes: Predicting Functions That Could Be Relevant for Improving Biomass Transformation Processes

“…The cell wall is a dynamic structure involved in several physiological processes such as: cell growth [11], defense against pathogens [12], or signaling [13]. In sugarcane, the cell wall also plays a key role in the distribution of sucrose [14].…”