Production and characterization of auxin-insensitive rice by overexpression of a mutagenized rice IAA protein.
Since auxin was first isolated and characterized as a plant hormone, the underlying molecular mechanism of auxin signaling has been elucidated primarily in dicot plants represented by Arabidopsis. In monocot plants, the molecular mechanism of auxin signaling has remained unclear, despite various physiological experiments. To understand the function and mechanism of auxin signaling in rice (Oryza sativa), we focused on the IAA gene, a well-studied gene in Arabidopsis that serves as a negative regulator of auxin signaling. We found 24 IAA gene family members in the rice genome. OsIAA3 is one of these family members whose expression is rapidly increased in response to auxin. We produced transgenic rice harboring mOsIAA3-GR, which can overproduce mutant OsIAA3 protein containing an amino acid change in domain II to cause a gain-of-function phenotype, by treatment with dexamethasone. The transgenic rice was insensitive to auxin and gravitropic stimuli, and exhibited short leaf blades, reduced crown root formation, and abnormal leaf formation. These results suggest that, in rice, auxin is important for development and its signaling is mediated by IAA genes.
Nakamura
Ayako
A
Bioscience and Biotechnology Center, Nagoya University, Chikusa, Nagoya, Aichi 464-8601, Japan.
Umemura
Iichiro
I
Gomi
Kenji
K
Hasegawa
Yasuko
Y
Kitano
Hidemi
H
Sazuka
Takashi
T
Matsuoka
Makoto
M
D000581:Amidohydrolases / Q000235:genetics*; D017360:Arabidopsis / Q000235:genetics; D001483:Base Sequence; D017931:DNA Primers; D003907:Dexamethasone / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018745:Genome, Plant; D007210:Indoleacetic Acids / Q000494:pharmacology*; D012275:Oryza / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics; D030821:Plants, Genetically Modified / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects
D017931:DNA Primers; D007210:Indoleacetic Acids; D010940:Plant Proteins; D003907:Dexamethasone; D000581:Amidohydrolases