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White‐core endosperm floury endosperm‐4 in rice is generated by knockout mutations in the C 4 ‐type pyruvate orthophosphate dikinase gene ( OsPPDKB )
Author(s) -
Kang HongGyu,
Park Sunhee,
Matsuoka Makoto,
An Gynheung
Publication year - 2005
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2005.02423.x
Subject(s) - endosperm , scutellum , mutant , aleurone , wild type , gene , starch , biochemistry , biology , immunogold labelling , chemistry , microbiology and biotechnology , botany , ultrastructure
Summary 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.