Du3, a mRNA cap-binding protein gene, regulates amylose content in Japonica rice seeds
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Five non-allelic <i>dull</i> (<i>du</i>) mutants have been isolated and characterized as low amylose mutants in rice (<i>Oryza sativa</i>) endosperm. Synthesis of amylose is controlled by <i>Waxy</i> the gene that encodes granule-bound starch synthase. We previously showed that the <i>du1</i> and <i>du2</i> proteins may encode general splicing regulators which affect the expression level and splicing efficiency of <i>Waxy<sup>b</sup></i> (<i>Wx<sup>b</sup></i>), an allele that has a single-base mutation in the 5′ splice site of intron 1. Here we report that the <i>du</i>3 mutant has also reduced the splicing efficiency of <i>Wx<sup>b</sup></i> pre-mRNA. Furthermore, map-based cloning revealed that <i>Du3</i> encodes the rice homolog of a cap-binding protein 20 kD subunit (CBP20), a component of the heterodimeric nuclear cap-binding complex (CBC) playing a role in pre-mRNA splicing, RNA nuclear export, and nonsense-mediated decay. Transient expression of green fluorescent protein (GFP)-tagged <i>Du3</i> proteins in rice protoplasts resulted in localization to the nucleus showing a speckled pattern similar to the pattern displayed by other splicing factors.
- Plant tissue culture letters
Plant tissue culture letters 25(5), 483-487, 2008-12-01
Japanese Society for Plant Cell and Molecular Biology