title: Loss of cytosolic fructose-1,6-bisphosphatase limits photosynthetic sucrose synthesis and causes severe growth retardations in rice (Oryza sativa).
abstract: During photosynthesis, triose-phosphates (trioseP) exported from the chloroplast to the cytosol are converted to sucrose via cytosolic fructose-1,6-bisphosphatase (cFBPase). Expression analysis in rice suggests that OscFBP1 plays a major role in the cytosolic conversion of trioseP to sucrose in leaves during the day. The isolated OscFBP1 mutants exhibited markedly decreased photosynthetic rates and severe growth retardation with reduced chlorophyll content, which results in plant death. Analysis of primary carbon metabolites revealed both significantly reduced levels of sucrose, glucose, fructose and starch in leaves of these mutants, and a high accumulation of sucrose to starch in leaves of rice plants. In the oscfbp1 mutants, products of glycolysis and the TCA cycle were significantly increased. A partitioning experiment of (14)C-labelled photoassimilates revealed altered carbon distributions including a slight increase in the insoluble fraction representing transitory starch, a significant decrease in the neutral fraction corresponding to soluble sugars and a high accumulation of phosphorylated intermediates and carboxylic acid fractions in the oscfbp1 mutants. These results indicate that the impaired synthesis of sucrose in rice cannot be sufficiently compensated for by the transitory starch-mediated pathways that have been found to facilitate plant growth in the equivalent Arabidopsis mutants.
authors.affiliation: Plant Metabolism Research Center & Graduate School of Biotechnology, Kyung Hee University, Yongin 446-701, Korea.
authors.forename: Sang-Kyu
authors.initials: SK
authors.lastname: Lee
authors.forename: Jong-Seong
authors.initials: JS
authors.lastname: Jeon
authors.forename: Frederik
authors.initials: F
authors.lastname: Börnke
authors.forename: Lars
authors.initials: L
authors.lastname: Voll
authors.forename: Jung-Il
authors.initials: JI
authors.lastname: Cho
authors.forename: Chang-Hyo
authors.initials: CH
authors.lastname: Goh
authors.forename: Suk-Won
authors.initials: SW
authors.lastname: Jeong
authors.forename: Youn-Il
authors.initials: YI
authors.lastname: Park
authors.forename: Sung Jin
authors.initials: SJ
authors.lastname: Kim
authors.forename: Sang-Bong
authors.initials: SB
authors.lastname: Choi
authors.forename: Akio
authors.initials: A
authors.lastname: Miyao
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Hirochika
authors.forename: Gynheung
authors.initials: G
authors.lastname: An
authors.forename: Man-Ho
authors.initials: MH
authors.lastname: Cho
authors.forename: Seong Hee
authors.initials: SH
authors.lastname: Bhoo
authors.forename: Uwe
authors.initials: U
authors.lastname: Sonnewald
authors.forename: Tae-Ryong
authors.initials: TR
authors.lastname: Hahn
mesh_terms: D002250:Carbon Radioisotopes / Q000378:metabolism; D002734:Chlorophyll / Q000032:analysis; D003600:Cytosol / Q000378:metabolism; D006597:Fructose-Bisphosphatase / Q000235:genetics / Q000378:metabolism*; D017343:Genes, Plant; D016254:Mutagenesis, Insertional; D009154:Mutation; D012275:Oryza / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D010710:Phosphates / Q000378:metabolism; D010788:Photosynthesis; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D018749:RNA, Plant / Q000235:genetics; D013213:Starch / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism*
chemical_list: D002250:Carbon Radioisotopes; D010710:Phosphates; D010940:Plant Proteins; D018749:RNA, Plant; D002734:Chlorophyll; D013395:Sucrose; D013213:Starch; D006597:Fructose-Bisphosphatase