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Loss of cytosolic fructose‐1,6‐bisphosphatase limits photosynthetic sucrose synthesis and causes severe growth retardations in rice ( Oryza sativa )
Author(s) -
LEE SANGKYU,
JEON JONGSEONG,
BÖRNKE FREDERIK,
VOLL LARS,
CHO JUNGIL,
GOH CHANGHYO,
JEONG SUKWON,
PARK YOUNIL,
KIM SUNG JIN,
CHOI SANGBONG,
MIYAO AKIO,
HIROCHIKA HIROHIKO,
AN GYNHEUNG,
CHO MANHO,
BHOO SEONG HEE,
SONNEWALD UWE,
HAHN TAERYONG
Publication year - 2008
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2008.01890.x
Subject(s) - sucrose , photosynthesis , fructose , cytosol , starch , biochemistry , chloroplast , mutant , oryza sativa , fructose 1,6 bisphosphatase , carbohydrate , glycolysis , chlorophyll , chemistry , biology , metabolism , botany , enzyme , gene
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.