摘要
Previously, we found 123 transcription factors（TFs） as candidate regulators of secondary cell wall（SCW）formation in rice by using phylogenetic and co-expression network analyses. Among them, we examined in this work the role of OsIDD_2, a zinc finger and indeterminate domain（IDD） family TF. Its overexpressors showed dwarfism, fragile leaves, and decreased lignin content, which are typical phenotypes of plants defective in SCW formation, whereas its knockout plants showed slightly increased lignin content.The RNA-seq and quantitative reverse transcription polymerase chain reaction analyses confirmed that some lignin biosynthetic genes were downregulated in the OsIDD_2-overexpressing plants, and revealed the same case for other genes involved in cellulose synthesis and sucrose metabolism. The transient expression assay using rice protoplasts revealed that OsIDD_2 negatively regulates the transcription of genes involved in lignin biosynthesis, cinnamyl alcohol dehydrogenase 2 and 3（CAD_2 and 3）, and sucrose metabolism, sucrose synthase 5（SUS_5）, whereas an Alpha Screen assay, which can detect the interaction between TFs and their target DNA sequences, directly confirmed the interaction between OsIDD_2 and the target sequences located in the promoter regions of CAD_2 and CAD_3. Based on these observations, we conclude that OsIDD_2 is negatively involved in SCW formation and other biological events by downregulating its target genes.
Previously, we found 123 transcription factors（TFs） as candidate regulators of secondary cell wall（SCW）formation in rice by using phylogenetic and co-expression network analyses. Among them, we examined in this work the role of OsIDD_2, a zinc finger and indeterminate domain（IDD） family TF. Its overexpressors showed dwarfism, fragile leaves, and decreased lignin content, which are typical phenotypes of plants defective in SCW formation, whereas its knockout plants showed slightly increased lignin content.The RNA-seq and quantitative reverse transcription polymerase chain reaction analyses confirmed that some lignin biosynthetic genes were downregulated in the OsIDD_2-overexpressing plants, and revealed the same case for other genes involved in cellulose synthesis and sucrose metabolism. The transient expression assay using rice protoplasts revealed that OsIDD_2 negatively regulates the transcription of genes involved in lignin biosynthesis, cinnamyl alcohol dehydrogenase 2 and 3（CAD_2 and 3）, and sucrose metabolism, sucrose synthase 5（SUS_5）, whereas an Alpha Screen assay, which can detect the interaction between TFs and their target DNA sequences, directly confirmed the interaction between OsIDD_2 and the target sequences located in the promoter regions of CAD_2 and CAD_3. Based on these observations, we conclude that OsIDD_2 is negatively involved in SCW formation and other biological events by downregulating its target genes.
基金
supported by grants from Grant-in-Aid for JSPS Research Fellow (JP15J03980 to H.Y.)
Series of single-year grants (26-1393 to K.H.)
Grants-in-Aid for Scientific Research on Innovative Areas (No.3806 to M.M. and M. U.-T.)
the Grant-in-Aid for Scientific Research (A) (JP26252001 to M.M.) and (B) (JP16H04907 to M. U.-T.)
