Characterization of an activation‐tagged mutant uncovers a role of GLABRA2 in anthocyanin biosynthesis in Arabidopsis. (17th June 2015)

• Record Type: Journal Article
• Authors: Wang, Xiaoyu; Wang, Xianling; Hu, Qingnan; Dai, Xuemei; Tian, Hainan; Zheng, Kaijie; Wang, Xiaoping; Mao, Tonglin; Chen, Jin‐Gui; Wang, Shucai
• Is Part Of: Plant journal. Volume 83:Number 2(2015:Jul.)
• Page Start: 300
• Page End: 311
• Publication Date: 2015-06-17
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12887
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12887-abs-0001"> <title>Summary</title> <p>In Arabidopsis, anthocyanin biosynthesis is controlled by a MYB‐bHLH‐WD40 (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 <italic>GLABRA2</italic> (<italic>GL2</italic>), 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 GL2 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 <italic>GL2</italic>, thus the mutant was named <italic>gl2‐1D</italic>. Consistent with the view that GL2 acts as a negative regulator of anthocyanin biosynthesis, <italic>gl2‐1D</italic> seedlings accumulated less whereas <italic>gl2‐3</italic> 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 <italic>gl2‐1D</italic> but elevated in <italic>gl2‐3</italic> mutants. Further analysis showed that expression of some MBW component genes involved in the regulation of late biosynthesis genes was reduced in <italic>gl2‐1D</italic> but elevated in <italic>gl2‐3</italic> mutants, and chromatin immunoprecipitation results indicated that some MBW component genes are targets of GL2. We also showed that GL2 functions as a transcriptional repressor. Taken together, these results indicate that GL2 negatively regulates anthocyanin biosynthesis in Arabidopsis by directly repressing the expression of some MBW component genes.</p> </abstract>