Function and expression pattern of the alpha subunit of the heterotrimeric G protein in rice.
The d1 mutant, which is deficient for the heterotrimeric G-protein alpha subunit (Galpha) gene of rice, shows dwarfism and sets small round seeds. To determine whether dwarfism in d1 is due to a reduction in cell number or to shortened cell length, the cell number of the leaf sheath, the internode, the root and the lemma was compared between Nipponbare, a wild-type rice and d1-5, a d1 allele derived from Nipponbare. Our results indicate that the cell number was reduced in all organs analyzed in d1-5. In addition, cell enlargement was found in roots and lemma of d1-5, although the organ length in d1-5 was shorter than that of wild-type rice. These results suggest that rice Galpha participates in cell proliferation in rice. Western blot analyses using anti-Galpha antibody and RT-PCR analyses indicate that Galpha is mostly expressed in the developing organs. Galpha promoter activity studies using the GUS reporter gene confirmed that the expression of Galpha was highest in developing organs. We conclude that rice Galpha participates in the regulation of cell number in a developmental stage-dependent manner.
Izawa
Yuki
Y
Department of Bioscience, Fukui Prefectural University, 4-1-1 Matsuoka Kenjyojima, Eiheiji-cho, Yoshida-gun, Fukui, 910-1195 Japan.
Takayanagi
Yoshiyuki
Y
Inaba
Noriko
N
Abe
Yuki
Y
Minami
Miho
M
Fujisawa
Yukiko
Y
Kato
Hisaharu
H
Ohki
Shizuka
S
Kitano
Hidemi
H
Iwasaki
Yukimoto
Y
D002452:Cell Count; D049109:Cell Proliferation; D048429:Cell Size; D044385:GTP-Binding Protein alpha Subunits / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D012275:Oryza / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D018749:RNA, Plant / Q000235:genetics
D044385:GTP-Binding Protein alpha Subunits; D010940:Plant Proteins; D018749:RNA, Plant