title: 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.
authors.affiliation: CSIRO Agriculture, Queensland Bioscience Precinct, 306 Carmody Rd, St Lucia, QLD, 4067, Australia. Rosanne.Casu@csiro.au.
authors.forename: Rosanne E
authors.initials: RE
authors.lastname: Casu
authors.affiliation: CSIRO Agriculture, Queensland Bioscience Precinct, 306 Carmody Rd, St Lucia, QLD, 4067, Australia.
authors.forename: Anne L
authors.initials: AL
authors.lastname: Rae
authors.affiliation: CSIRO Agriculture, Queensland Bioscience Precinct, 306 Carmody Rd, St Lucia, QLD, 4067, Australia.
authors.forename: Janine M
authors.initials: JM
authors.lastname: Nielsen
authors.affiliation: CSIRO Agriculture, Queensland Bioscience Precinct, 306 Carmody Rd, St Lucia, QLD, 4067, Australia.
authors.forename: Jai M
authors.initials: JM
authors.lastname: Perroux
authors.affiliation: CSIRO Agriculture, Queensland Bioscience Precinct, 306 Carmody Rd, St Lucia, QLD, 4067, Australia.
authors.forename: Graham D
authors.initials: GD
authors.lastname: Bonnett
authors.affiliation: CSIRO Agriculture, Queensland Bioscience Precinct, 306 Carmody Rd, St Lucia, QLD, 4067, Australia.
authors.forename: John M
authors.initials: JM
authors.lastname: Manners
mesh_terms: D002473:Cell Wall / Q000378:metabolism; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005964:Glucosyltransferases / Q000235:genetics*; D026901:Membrane Transport Proteins / Q000235:genetics*; D005810:Multigene Family; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics*; D058526:Plant Vascular Bundle / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D031786:Saccharum / Q000235:genetics* / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D026901:Membrane Transport Proteins; D010940:Plant Proteins; C078729:sucrose transport protein, plant; D005964:Glucosyltransferases; C478648:cellulose synthase
keywords: Cell wall metabolism; Cellulose synthase; Culm; Saccharum; Stalk; Sucrose transporter; Transcriptome analysis