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Characterization of an activation‐tagged mutant uncovers a role of GLABRA 2 in anthocyanin biosynthesis in Arabidopsis
Author(s) -
Wang Xiaoyu,
Wang Xianling,
Hu Qingnan,
Dai Xuemei,
Tian Hainan,
Zheng Kaijie,
Wang Xiaoping,
Mao Tonglin,
Chen JinGui,
Wang Shucai
Publication year - 2015
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/tpj.12887
Subject(s) - arabidopsis , biology , mutant , myb , repressor , transcription factor , chromatin immunoprecipitation , genetics , biochemistry , gene , microbiology and biotechnology , promoter , gene expression
Summary In Arabidopsis, anthocyanin biosynthesis is controlled by a MYB ‐ bHLH ‐ WD 40 ( MBW ) transcriptional activator complex. The MBW complex activates the transcription of late biosynthesis genes in the flavonoid pathway, leading to the production of anthocyanins. A similar MBW complex regulates epidermal cell fate by activating the transcription of GLABRA 2 ( GL 2 ), a homeodomain transcription factor required for trichome formation in shoots and non‐hair cell formation in roots. Here we provide experimental evidence to show that GL 2 also plays a role in regulating anthocyanin biosynthesis in Arabidopsis. From an activation‐tagged mutagenized population of Arabidopsis plants, we isolated a dominant, gain‐of‐function mutant with reduced anthocyanins. Molecular cloning revealed that this phenotype is caused by an elevated expression of GL 2 , thus the mutant was named gl2‐1D . Consistent with the view that GL 2 acts as a negative regulator of anthocyanin biosynthesis, gl2‐1D seedlings accumulated less whereas gl2‐3 seedlings accumulated more anthocyanins in response to sucrose. Gene expression analysis indicated that expression of late, but not early, biosynthesis genes in the flavonoid pathway was dramatically reduced in gl2‐1D but elevated in gl2‐3 mutants. Further analysis showed that expression of some MBW component genes involved in the regulation of late biosynthesis genes was reduced in gl2‐1D but elevated in gl2‐3 mutants, and chromatin immunoprecipitation results indicated that some MBW component genes are targets of GL 2. We also showed that GL 2 functions as a transcriptional repressor. Taken together, these results indicate that GL 2 negatively regulates anthocyanin biosynthesis in Arabidopsis by directly repressing the expression of some MBW component genes.