Reference "White-core endosperm floury endosperm-4 in rice is generated by knockout mutations in the C-type pyruvate orthophosphate dikinase gene (OsPPDKB)"

Reference ID

11107

Title

White-core endosperm floury endosperm-4 in rice is generated by knockout mutations in the C-type pyruvate orthophosphate dikinase gene (OsPPDKB)

Source

The Plant journal : for cell and molecular biology, 2005, vol. 42, pp. 901-911

Authors (4)

Kang-H-G	Park-S
Matsuoka-M	An-G

Abstract

We have isolated a floury endosperm-4 (flo4) rice mutant with a floury-white
endosperm but a normal outer portion. Scanning electron microscopic analysis
revealed that this abnormal endosperm consisted of loosely packed starch
granules. The mutant phenotype was generated by T-DNA insertion into the fifth
intron of the OsPPDKB gene encoding pyruvate orthophosphate dikinase (PPDK).
Plants containing flo4-1 produced no OsPPDKB transcript or the OsPPDKB protein
in their developing kernels and leaves. We obtained two additional alleles, flo4-
2 and flo4-3, that also showed the same white-core endosperm phenotype. The flo4
kernels weighed about 6% less than wild-type ones. Starch contents in both
kernel types were similar, but the total protein content was slightly higher in
the mutant kernels. Moreover, lipid contents were significantly increased in the
flo4 kernels. Expression analyses demonstrated that the cytosolic mRNA of
OsPPDKB was induced in the reproductive organs after pollination, and greatly
increased until about 10 days after fertilization. This mRNA was localized
mainly in the endosperm, aleurone, and scutellum of the developing kernel. Our
results suggest that cytosolic PPDK functions in rice to modulate carbon
metabolism during grain filling.