A novel factor FLOURY ENDOSPERM2 is involved in regulation of rice grain size and starch quality.
Rice (Oryza sativa) endosperm accumulates a massive amount of storage starch and storage proteins during seed development. However, little is known about the regulatory system involved in the production of storage substances. The rice flo2 mutation resulted in reduced grain size and starch quality. Map-based cloning identified FLOURY ENDOSPERM2 (FLO2), a member of a novel gene family conserved in plants, as the gene responsible for the rice flo2 mutation. FLO2 harbors a tetratricopeptide repeat motif, considered to mediate a protein-protein interactions. FLO2 was abundantly expressed in developing seeds coincident with production of storage starch and protein, as well as in leaves, while abundant expression of its homologs was observed only in leaves. The flo2 mutation decreased expression of genes involved in production of storage starch and storage proteins in the endosperm. Differences between cultivars in their responsiveness of FLO2 expression during high-temperature stress indicated that FLO2 may be involved in heat tolerance during seed development. Overexpression of FLO2 enlarged the size of grains significantly. These results suggest that FLO2 plays a pivotal regulatory role in rice grain size and starch quality by affecting storage substance accumulation in the endosperm.
She
Kao-Chih
KC
Department of Biological Science and Technology, Tokyo University of Science, Noda, Japan.
Kusano
Hiroaki
H
Koizumi
Kazuyoshi
K
Yamakawa
Hiromoto
H
Hakata
Makoto
M
Imamura
Tomohiro
T
Fukuda
Masato
M
Naito
Natsuka
N
Tsurumaki
Yumi
Y
Yaeshima
Mitsuhiro
M
Tsuge
Tomohiko
T
Matsumoto
Ken'ichiro
K
Kudoh
Mari
M
Itoh
Eiko
E
Kikuchi
Shoshi
S
Kishimoto
Naoki
N
Yazaki
Junshi
J
Ando
Tsuyu
T
Yano
Masahiro
M
Aoyama
Takashi
T
Sasaki
Tadamasa
T
Satoh
Hikaru
H
Shimada
Hiroaki
H
D000687:Amylopectin / Q000032:analysis; D000688:Amylose / Q000032:analysis; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000235:genetics; D056625:Endosperm / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D005936:Glucans / Q000032:analysis; D006358:Hot Temperature; D008969:Molecular Sequence Data; D009154:Mutation; D012275:Oryza / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D055314:Seed Storage Proteins / Q000235:genetics / Q000378:metabolism*; D013213:Starch / Q000032:analysis*
D018744:DNA, Plant; D005936:Glucans; D055314:Seed Storage Proteins; D013213:Starch; D000688:Amylose; D000687:Amylopectin; C040088:1,4-glucan