Premium
MYB 46 directly regulates the gene expression of secondary wall‐associated cellulose synthases in A rabidopsis
Author(s) -
Kim WonChan,
Ko JaeHeung,
Kim JooYeol,
Kim Jungmook,
Bae HyeunJong,
Han KyungHwan
Publication year - 2013
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2012.05124.x
Subject(s) - myb , biology , transcription factor , gene , chromatin immunoprecipitation , promoter , ectopic expression , gene expression , microbiology and biotechnology , biochemistry
Summary Cellulose is the most abundant biopolymer on Earth. Three cellulose synthases ( CESA 4, CESA 7 and CESA 8) are necessary for cellulose production in the secondary cell walls of A rabidopsis. Little is known about how expression of these CESA genes is regulated. We recently identified a cis ‐regulatory element ( M 46 RE ) that is recognized by MYB 46, which is a master switch for secondary wall formation in A rabidopsis. A genome‐wide survey of promoter sequences for the presence of M 46 RE s led to the hypothesis that MYB 46 may function as a direct regulator of all three secondary wall‐associated cellulose synthase genes: CESA4 , CESA7 and CESA8 . We tested this hypothesis using several lines of experimental evidence. All three CESA genes are highly up‐regulated by both constitutive and inducible over‐expression of MYB46 in planta . Using a steroid receptor‐based inducible activation system, we show that MYB 46 directly activates transcription of the three CESA genes. We then used an electrophoretic mobility shift assay and chromatin immunoprecipitation analysis to confirm that MYB 46 protein directly binds to the promoters of the three CESA genes both in vitro and in vivo . Furthermore, ectopic up‐regulation of MYB46 resulted in a significant increase of crystalline cellulose content in A rabidopsis. Taken together, we have identified MYB 46 as a transcription factor that directly regulates all three secondary wall‐associated CESA genes. Yeast one‐hybrid screening identified additional transcription factors that regulate the CESA genes. However, none of the putative regulators appears to be regulated by MYB 46, suggesting the multi‐faceted nature of transcriptional regulation of secondary wall cellulose biosynthesis.