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J Plant Res. 2017 Jan;130(1):45-55. doi: 10.1007/s10265-016-0886-0. Epub 2016 Dec 19.

Double-stranded RNA-binding protein DRB3 negatively regulates anthocyanin biosynthesis by modulating PAP1 expression in Arabidopsis thaliana.

Author information

1
Departments of Applied Biological Sciences, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo, 183-8509, Japan.
2
Molecular and Environmental Plant Sciences, Department of Horticultural Sciences, Vegetable and Fruit Development Center, Texas A&M University, College Station, TX, 77843, USA.
3
Department of Clinical Plant Science, Hosei University, 3-7-2 Kajino-cho, Koganei, Tokyo, 184-8584, Japan.
4
Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima, Tokyo, Japan.
5
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan.
6
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan.
7
Innovation Advancement Organization, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo, 183-8509, Japan.
8
Departments of Applied Biological Sciences, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo, 183-8509, Japan. fuku@cc.tuat.ac.jp.
9
Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo, 183-8509, Japan. fuku@cc.tuat.ac.jp.

Abstract

The model plant Arabidopsis thaliana has five double-stranded RNA-binding proteins (DRB1-DRB5), two of which, DRB1 and DRB4, are well characterized. In contrast, the functions of DRB2, DRB3 and DRB5 have yet to be elucidated. In this study, we tried to uncover their functions using drb mutants and DRB-over-expressed lines. In over-expressed lines of all five DRB genes, the over-expression of DRB2 or DRB3 (DRB2ox or DRB3ox) conferred a downward-curled leaf phenotype, but the expression profiles of ten small RNAs were similar to that of the wild-type (WT) plant. Phenotypes were examined in response to abiotic stresses. Both DRB2ox and DRB3ox plants exhibited salt-tolerance. When these plants were exposed to cold stress, drb2 and drb3 over-accumulated anthocyanin but DRB2ox and DRB3ox did not. Therefore, the over-expression of DRB2 or DRB3 had pleiotropic effects on host plants. Microarray and deep-sequencing analyses indicated that several genes encoding key enzymes for anthocyanin biosynthesis, including chalcone synthase (CHS), dihydroflavonol reductase (DFR) and anthocyanidin synthase (ANS), were down-regulated in DRB3ox plants. When DRB3ox was crossed with the pap1-D line, which is an activation-tagged transgenic line that over-expresses the key transcription factor PAP1 (Production of anthocyanin pigmentation1) for anthocyanin biosynthesis, over-expression of DRB3 suppressed the expression of PAP1, CHS, DFR and ANS genes. DRB3 negatively regulates anthocyanin biosynthesis by modulating the level of PAP1 transcript. Since two different small RNAs regulate PAP1 gene expression, a possible function of DRB3 for small RNA biogenesis is discussed.

KEYWORDS:

Anthocyanin; Cold stress; DRB3; DsRNA-binding protein; PAP1; Small RNA

PMID:
27995376
DOI:
10.1007/s10265-016-0886-0
[Indexed for MEDLINE]

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