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Plant Cell Rep. 2017 Dec;36(12):1889-1902. doi: 10.1007/s00299-017-2203-3. Epub 2017 Sep 13.

GmMYB58 and GmMYB205 are seed-specific activators for isoflavonoid biosynthesis in Glycine max.

Han X1,2, Yin Q1,2, Liu J1,2, Jiang W1, Di S1, Pang Y3.

Author information

1
The Key Laboratory of Plant Resources/Beijing Botanical Garden, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China.
2
University of Chinese Academy of Sciences, Beijing, 100049, China.
3
The Key Laboratory of Plant Resources/Beijing Botanical Garden, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China. yzhpang@ibcas.ac.cn.

Abstract

GmMYB58 and GmMYB205 are key positive regulators that are involved in isoflavonoid biosynthesis in seeds of Glycine max, and they activate the expression of several structural genes in the isoflavonoid pathway. MYB transcription factors (TFs) are major regulators involved in flavonoid/isoflavonoid biosynthesis in many plant species. However, functions of most MYB TFs remain unknown in flavonoid/isoflavonoid pathway in Glycine max. In this study, we identified 321 MYB TFs by genome-wide searching, and further isolated and functionally characterized two MYB TFs, GmMYB58 and GmMYB205. The deduced GmMYB58 and GmMYB205 proteins contain highly conserved R2R3 repeat domain at the N-terminal region that is the signature motif of R2R3-type MYB TFs. GmMYB58 and GmMYB205 were highly expressed in early seed development stages than in the other tested organs. GmMYB58 and GmMYB205 GFP fusion proteins were found to be localized in the nucleus when they were transiently expressed in Arabidopsis thaliana mesophyll protoplast. Both GmMYB58 and GmMYB205 can activate the promoter activities of GmCHS, GmIFS2, and GmHID in the transient trans-activation assays, and the activation of GmHID by both GmMYB58 and GmMYB205 was further confirmed by yeast one-hybrid assay. In addition, over-expression of GmMYB58 and GmMYB205 resulted in significant increases in expression levels of several pathway genes in soybean hairy roots, in particular, IFS2 by more than fivefolds in GmMYB205-over-expressing lines. Moreover, isoflavonoid contents were remarkably enhanced in the GmMYB58 and GmMYB205 over-expressing hairy roots than in the control. Our results suggest that GmMYB58 and GmMYB205 are seed-specific TFs, and they can enhance isoflavonoid biosynthesis mainly through the regulation of GmIFS2 and GmHID in G. max.

KEYWORDS:

Glycine max; Hairy roots; Isoflavonoid biosynthesis; MYB transcription factors

PMID:
28905215
DOI:
10.1007/s00299-017-2203-3
[Indexed for MEDLINE]

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