title: Tissue specificity and diurnal change in gene expression of the sucrose phosphate synthase gene family in rice.
abstract: The rice genome contains 5 isogenes for sucrose phosphate synthase (SPS), the key enzyme in sucrose synthesis; however, little is known about their transcriptional regulation. In order to determine the expression patterns of the SPS gene family in rice plants, we conducted an expression analysis in various tissues and developmental stages by real-time quantitative RT-PCR. At the transcript level, the rice SPS genes, particularly SPS1, were preferentially expressed in source tissues, whereas SPS2, SPS6, and SPS8 were expressed equally in source and sink tissues. We also investigated diurnal changes in SPS gene expression, SPS activity, and soluble sugar content in leaf blades. Interestingly, the expression of all the SPS genes, particularly that of SPS1 and SPS11, tended to be higher at night when the activation state of the SPS proteins was low, and the mRNA levels of SPS1 and SPS6 were negatively correlated with sucrose content. Furthermore, the temporal patterns of SPS gene expression and sugar content under continuous light conditions suggested the involvement of endogenous rhythm and/or sucrose sensing in the transcriptional regulation of SPS genes. Our data revealed differential expression patterns in the rice SPS gene family and part of the complex mechanisms of their transcriptional control.
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Okamura
authors.forename: Naohiro
authors.initials: N
authors.lastname: Aoki
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Hirose
authors.forename: Madoka
authors.initials: M
authors.lastname: Yonekura
authors.forename: Chikara
authors.initials: C
authors.lastname: Ohto
authors.forename: Ryu
authors.initials: R
authors.lastname: Ohsugi
mesh_terms: D002241:Carbohydrates / Q000032:analysis; D002940:Circadian Rhythm / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D018525:Germination; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism; D008027:Light; D005810:Multigene Family / Q000235:genetics; D009928:Organ Specificity / Q000235:genetics; D012275:Oryza / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D036226:Seedlings / Q000201:enzymology / Q000235:genetics / Q000502:physiology
chemical_list: D002241:Carbohydrates; D010940:Plant Proteins; D012333:RNA, Messenger; D005964:Glucosyltransferases; C022698:sucrose-phosphate synthase