| Categories genes  | Tags grain yield  grain  cell death  shoot  meristem  endosperm  yield  seed  seed development  shoot apical meristem  growth  seedling  grain size  breeding 
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  • Key message
    • Overexpression of GE promoted cell proliferation and enhanced rice plant growth and grain yield, but reduced embryo size, suggesting that GE is critical for coordinating rice embryo and endosperm development
    • The function of GE in each tissue is distinct, controlling cell size in the embryo and cell death in the endosperm
    • Post-embryonic growth of ge seedling was severely inhibited due to defective shoot apical meristem (SAM) maintenance
    • GE, which encodes CYP78A13, is predominantly expressed in the interfacing tissues of the both embryo and endosperm
    • In contrast to the loss-of-function mutant with large embryo and small endosperm, GE overexpression causes a small embryo and enlarged endosperm
    • A complementation analysis coupled with heterofertilization showed that complementation of ge mutation in either embryo or endosperm failed to restore the wild-type embryo/endosperm ratio
    • Among genes associated with embryo/endosperm size, REDUCED EMBRYO genes, whose loss-of-function causes a phenotype opposite to ge, are revealed to regulate endosperm size upstream of GE
    • To fully understand the embryo-endosperm size control, the genetic network of the related genes should be elucidated
    • However, the molecular mechanism(s) underlying embryo and endosperm development remains largely unknown, particularly in rice, the model cereal
    • GE is expressed predominantly in the scutellar epithelium, the interface region between embryo and endosperm
    • Mutation of GE resulted in a large embryo in the seed, which was caused by excessive expansion of scutellum cells
    • Moreover, transgenic Arabidopsis plants overexpressing AtCYP78A10, a GE homolog, also produced bigger seeds, implying a conserved role for the CYP78A subfamily of P450s in regulating seed development
    • 2 showed that both can promote grain growth
    • Variations in CYP78A13 coding region influence grain size and yield in rice.
    • Grain size is one of the most important determinants of crop yield in cereals
    • Here, we identified a dominant mutant, big grain2 (bg2-D) from our enhancer-trapping population
    • Sequence search revealed that CYP78A13 has a paralogue Grain<U+2005>Length 3
    • Detailed examination of the transgenic plants with chimaeric constructs suggested that variation in CYP78A13 coding region is responsible for the variation of grain yield
    • Taken together, our results suggest that the variations in CYP78A13 in the indica varieties hold potential in rice breeding for application of grain yield improvement
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