The OsFOR1 gene encodes a polygalacturonase-inhibiting protein (PGIP) that regulates floral organ number in rice.
We have isolated a cDNA clone, OsFOR1, from the immature panicles of rice. The OsFOR1 (Oryza sativa floral organ regulator 1) gene encodes a protein that contains a leucine-rich repeat (LRR) domain. This domain comprises 10 tandem repeats of a canonical 24-amino acid LRR sequence. The structure and the number of LRRs for OsFOR1 are similar to those of polygalacturonase-inhibiting proteins (PGIPs) from various other plant species. Moreover, the OsFOR1 recombinant protein, when fused to maltose-binding protein (MBP), shows PGIP activity against the Aspergillus niger polygalacturonase. OsFOR1 is highly expressed in the calli and immature and mature panicles, while detectable at only low levels in seedling roots and mature stems. In situ hybridization experiments showed the transcripts of OsFOR1 are present in young spikelet primordia and in almost all of the young floral organs. Transgenic approaches were used to study in vivo functioning. Antisense expression of OsFOR1 resulted in an increase in the numbers of floral organs, including the stamen, carpel, palea/lemma, stigma, and lodicule. OsFOR1 transcript was not detected in the frizzy panicle mutant, which is defective in its spikelet formation but normal in inflorescence-meristem initiation and maintenance. Therefore, we suggest that OsFOR1 plays a role in the formation and/or maintenance of floral organ primordia.
Jang
Seonghoe
S
National Laboratory of Plant Functional Genomics, Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea.
Lee
Byongho
B
Kim
Chanhong
C
Kim
Soo-Jin
SJ
Yim
Jieun
J
Han
Jong-Jin
JJ
Lee
Shinyoung
S
Kim
Seong-Ryong
SR
An
Gynheung
G
D000595:Amino Acid Sequence; D016373:DNA, Antisense / Q000235:genetics; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D035264:Flowers / Q000235:genetics / Q000254:growth & development*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D007930:Leucine / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D012275:Oryza / Q000235:genetics* / Q000254:growth & development; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D020449:Repetitive Sequences, Amino Acid / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D016373:DNA, Antisense; D018076:DNA, Complementary; C081479:PGIP protein, plant; D010940:Plant Proteins; D007930:Leucine