Alteration of floral organ identity in rice through ectopic expression of OsMADS16.
We used a transgenic approach and yeast two-hybrid experiments to study the role of the rice ( Oryza sativa L.) B-function MADS-box gene, OsMADS16. Transgenic rice plants were generated that ectopically expressed OsMADS16 under the control of the maize ( Zea mays L.) ubiquitin1 promoter. Microscopic observations revealed that the innermost-whorl carpels had been replaced by stamen-like organs, which resembled the flowers of the previously described Arabidopsis thaliana (L.) Heynh. mutation superman as well as those ectopically expressing the AP3 gene. These results indicate that expression of OsMADS16 in the innermost whorl induces stamen development. Occasionally, carpels had completely disappeared. In addition, ectopic expression of OsMADS16 enhanced expression of OsMADS4, another B-function gene, causing superman phenotypes. In the yeast two-hybrid system, OsMADS16 did not form a homodimer but, rather, the protein interacted with OsMADS4. OsMADS16 also interacted with OsMADS6 and OSMADS8, both of which are homologous to SEPALLATA proteins required for the proper function of class-B and class-C genes in Arabidopsis. Based on the gene expression pattern and our yeast two-hybrid data, we discuss a quartet model of MADS-domain protein interactions in the lodicule and stamen whorls of rice florets.
Lee
Sichul
S
National Research Laboratory of Plant Functional Genomics, Division of Molecular and Life Sciences, Pohang University of Science and Technology (POSTECH), 790-784 Pohang, Korea.
Jeon
Jong-Seong
JS
An
Kyungsook
K
Moon
Yong-Hwan
YH
Lee
Sanghee
S
Chung
Yong-Yoon
YY
An
Gynheung
G
D001483:Base Sequence; D017931:DNA Primers; D035264:Flowers / Q000033:anatomy & histology*; D018506:Gene Expression Regulation, Plant; D012275:Oryza / Q000033:anatomy & histology* / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D010940:Plant Proteins