| Categories genes  | Tags panicle  spikelet  grain  grain yield  yield  palea  lemma  grain filling  grain weight  development  starch  map-based cloning  grain size  sugar  quality  sucrose  grain quality  seed  seed size  grain length 
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    • Further, strong promoter::GUS expression was observed in the palea, lemma and the rachis branches in the young elongating panicles, which supported the role of OsINV3 in cell expansion and thus, in spikelet size and panicle length determination
    • OsINV3 was found to regulate spikelet size by playing a key role in cell expansion, driving the movement of assimilates for grain filling by modulating the hexose-to-sucrose ratio, contributing in grain weight determination and thus, the grain yield
    • In addition, strong promoter::GUS expression was observed in the dorsal end of ovary during the pre-storage phase until 6<U+00A0>days after flowering, highlighting a function for OsINV3 in monitoring the initial grain filling stage
    • OsINV3 mutants showed shorter panicles with lighter and smaller grains, owing to a smaller cell size on the outer and inner surfaces of the palea and lemma as observed by scanning electron microscopy
    • OsVIN2 encodes a vacuolar acid invertase that affects grain size by altering sugar metabolism in rice.
    • Collectively, OsVIN2 is involved in sugar metabolism, and thus regulates grain size; our findings provide insights into grain development and also suggest a potential strategy to improve grain quality and yield in rice
    • Furthermore, an altered sugar content with increased sucrose and decreased hexose levels, as well as changes in invertase and sucrose synthase activities, sugar transport gene expression, and starch constitution in sgs1 implies that OsVIN2 affects sucrose metabolism, including sugar composition, transport, and conversion from the source to the sink organs
    • Map-based cloning and complementation tests revealed that a DaiZ7 transposon insertion in a vacuolar invertase gene OsVIN2 is responsible for the mutant phenotype
    • Subcellular distribution and biochemical analysis indicated that OsVIN2 is located in the vacuolar lumen, and that its sucrose hydrolysis activity is maintained under acidic conditions
    • In a phenotypic analysis of the T-DNA insertion mutants, only the OsVIN2 mutant osvin2-1 exhibited reduced seed size and grain weight
    • A genetically complemented line with a native genomic clone of OsVIN2 rescued reduced VIN activity and seed size
    • These results clearly demonstrate an important role of OsVIN2 as sink strength modulator that is critical for the maintenance of sucrose flux into developing seed grains
    • OsINV3 and Its Homolog, OsINV2, Control Grain Size in Rice.
    • Loss-of-function of OsINV3 resulted in grains of smaller size when compared to the wild type, while overexpression showed increased grain size
    • Genetic data showed that OsINV2, that has no effect on grain size by itself, reduces grain length and width in the absence of OsINV3
    • In summary, we identified OsINV3 as a positive regulator of grain size in rice, and while OsINV2 has no function on grain size by itself
    • Both OsINV3 and OsINV2 are involved in sucrose metabolism, and thus regulate grain size
    • Our findings increase our understanding of the role of OsINV3 and its homolog, OsINV2, in grain size development and also suggest a potential strategy to improve grain yield in rice
    • Altered sugar content with increased sucrose and decreased hexose levels, as well as changes vacuolar invertase activities and starch constitution in INV3KO, INV2KO, INV3KOINV2KO mutants indicate that OsINV2 and OsINV3 affect sucrose metabolism in sink organs
    • Map-based cloning and genetic complementation showed that OsINV3 is responsible for the observed phenotype
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