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Xie Q, Xiong C, Yang Q, Zheng F, Larkin RM, Zhang J, Wang T, Zhang Y, Ouyang B, Lu Y, Ye J, Ye Z, Yang C. A novel regulatory complex mediated by Lanata (Ln) controls multicellular trichome formation in tomato. New Phytol 2022; 236:2294-2310. [PMID: 36102042 DOI: 10.1111/nph.18492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 09/02/2022] [Indexed: 06/15/2023]
Abstract
Trichomes that originate from plant aerial epidermis act as mechanical and chemical barriers against herbivores. Although several regulators have recently been identified, the regulatory pathway underlying multicellular trichome formation remains largely unknown in tomato. Here, we report a novel HD-ZIP IV transcription factor, Lanata (Ln), a missense mutation which caused the hairy phenotype. Biochemical analyses demonstrate that Ln separately interacts with two trichome regulators, Woolly (Wo) and Hair (H). Genetic and molecular evidence demonstrates that Ln directly regulates the expression of H. The interaction between Ln and Wo can increase trichome density by enhancing the expression of SlCycB2 and SlCycB3, which we previously showed are involved in tomato trichome formation. Furthermore, SlCycB2 represses the transactivation of the SlCycB3 gene by Ln and vice versa. Our findings provide new insights into the novel regulatory network controlling multicellular trichome formation in tomato.
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Affiliation(s)
- Qingmin Xie
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Cheng Xiong
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Qihong Yang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Fangyan Zheng
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Robert M Larkin
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Junhong Zhang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Taotao Wang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yuyang Zhang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Bo Ouyang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yongen Lu
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jie Ye
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Zhibiao Ye
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Changxian Yang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
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Wang Y, Tian H, Wang W, Wang X, Zheng K, Hussain S, Lin R, Wang T, Wang S. The Carboxyl-Terminus of TRANSPARENT TESTA GLABRA1 Is Critical for Its Functions in Arabidopsis. Int J Mol Sci 2021; 22:ijms221810039. [PMID: 34576199 PMCID: PMC8467004 DOI: 10.3390/ijms221810039] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/13/2021] [Accepted: 09/14/2021] [Indexed: 11/23/2022] Open
Abstract
The Arabidopsis WD40 repeat protein TRANSPARENT TESTA GLABRA1 (TTG1) regulates cell fate determination, including trichome initiation and root hair formation, as well as secondary metabolism such as flavonoid biosynthesis and seed coat mucilage production. TTG1 regulates different processes via regulating the expression of its downstream target genes by forming MYB-bHLH-WD40 (MBW) activator complexes with different R2R3 MYB and bHLH transcription factors. Here, we report the identification of the carboxyl (C)-terminus as a critical domain for TTG1′s functions in Arabidopsis. We found that the ttg1Δ15aa mutant shows pleiotropic phenotypes identical to a TTG1 loss-of-function mutant. Gene sequencing indicates that a single nucleotide substitution in TTG1 led to a premature stop at the W327 residue, leading to the production of a truncated TTG1 protein with a deletion of the last 15 C-terminal amino acids. The expression of TTG1 under the control of its native promoter fully restored the ttg1Δ15aa mutant phenotypes. Consistent with these observations, the expression levels of TTG1 downstream genes such as GLABRA2 (GL2) and CAPRICE (CPC) were reduced in the ttg1Δ15aa mutant. Assays in Arabidopsis protoplast show that TTG1Δ15aa failed to interact with the bHLH transcription factor GL3, and the deletion of the last 3 C-terminal amino acids or the 339L amino acid alone fully abolished the interaction of TTG1 with GL3. Furthermore, the expression of TTG1Δ3aa under the control of TTG1 native promoter failed to restore the ttg1Δ15aa mutant phenotypes. Taken together, our results suggest that the C-terminal domain of TTG1 is required for its proper function in Arabidopsis.
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Affiliation(s)
- Yating Wang
- Laboratory of Plant Molecular Genetics & Crop Gene Editing, School of Life Sciences, Linyi University, Linyi 276000, China; (Y.W.); (W.W.); (X.W.)
- Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun 130024, China; (H.T.); (K.Z.); (S.H.); (R.L.); (T.W.)
| | - Hainan Tian
- Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun 130024, China; (H.T.); (K.Z.); (S.H.); (R.L.); (T.W.)
| | - Wei Wang
- Laboratory of Plant Molecular Genetics & Crop Gene Editing, School of Life Sciences, Linyi University, Linyi 276000, China; (Y.W.); (W.W.); (X.W.)
| | - Xutong Wang
- Laboratory of Plant Molecular Genetics & Crop Gene Editing, School of Life Sciences, Linyi University, Linyi 276000, China; (Y.W.); (W.W.); (X.W.)
| | - Kaijie Zheng
- Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun 130024, China; (H.T.); (K.Z.); (S.H.); (R.L.); (T.W.)
- Key Laboratory of Soybean Molecular Design Breeding, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
| | - Saddam Hussain
- Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun 130024, China; (H.T.); (K.Z.); (S.H.); (R.L.); (T.W.)
| | - Rao Lin
- Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun 130024, China; (H.T.); (K.Z.); (S.H.); (R.L.); (T.W.)
| | - Tianya Wang
- Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun 130024, China; (H.T.); (K.Z.); (S.H.); (R.L.); (T.W.)
| | - Shucai Wang
- Laboratory of Plant Molecular Genetics & Crop Gene Editing, School of Life Sciences, Linyi University, Linyi 276000, China; (Y.W.); (W.W.); (X.W.)
- Correspondence:
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Hussain S, Zhang N, Wang W, Ahmed S, Cheng Y, Chen S, Wang X, Wang Y, Hu X, Wang T, Wang S. Involvement of ABA Responsive SVB Genes in the Regulation of Trichome Formation in Arabidopsis. Int J Mol Sci 2021; 22:6790. [PMID: 34202673 DOI: 10.3390/ijms22136790] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/18/2021] [Accepted: 06/20/2021] [Indexed: 01/19/2023] Open
Abstract
Trichome formation in Arabidopsis is regulated by several key regulators, and plants hormones such as gibberellin, salicylic acid, jasmonic acid and cytokinins have been shown to regulate trichome formation by affecting the transcription or activities of the key regulators. We report here the identification of two abscisic acid (ABA) responsive genes, SMALLER TRICHOMES WITH VARIABLE BRANCHES (SVB) and SVB2 as trichome formation regulator genes in Arabidopsis. The expression levels of SVB and SVB2 were increased in response to ABA treatment, their expression levels were reduced in the ABA biosynthesis mutant aba1-5, and they have similar expression pattern. In addition to the trichome defects reported previously for the svb single mutant, we found that even though the trichome numbers were largely unaffected in both the svb and svb2 single mutants generate by using CRISPR/Cas9 gene editing, the trichome numbers were greatly reduced in the svb svb2 double mutants. On the other hand, trichome numbers were increased in SVB or SVB2 overexpression plants. RT-PCR results show that the expression of the trichome formation key regulator gene ENHANCER OF GLABRA3 (EGL3) was affected in the svb svb2 double mutants. Our results suggest that SVB and SVB2 are ABA responsive genes, and SVB and SVB2 function redundantly to regulate trichome formation in Arabidopsis.
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Wu ML, Cui YC, Ge L, Cui LP, Xu ZC, Zhang HY, Wang ZJ, Zhou D, Wu S, Chen L, Cui H. NbCycB2 represses Nbwo activity via a negative feedback loop in tobacco trichome development. J Exp Bot 2020; 71:1815-1827. [PMID: 31990970 PMCID: PMC7242068 DOI: 10.1093/jxb/erz542] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 01/25/2020] [Indexed: 05/20/2023]
Abstract
The transcription factor Woolly (Wo) and its downstream gene CycB2 have been shown to regulate trichome development in tomato (Solanum lycopersicum). It has been demonstrated that only the gain-of-function allele of Slwo (SlWoV, the Slwo woolly motif mutant allele) can increase the trichome density; however, it remains unclear why the two alleles function differently in trichome development. In this study, we used Nicotiana benthamiana as a model and cloned the homologues of Slwo and SlCycB2 (named Nbwo and NbCycB2). We also constructed a Nbwo gain-of-function allele with the same mutation site as SlWoV (named NbWoV). We found that both Nbwo and NbWoV directly regulate NbCycB2 and their own expression by binding to the promoter of NbCycB2 and their own genomic sequences. As form of a feedback regulation, NbCycB2 negatively regulates trichome formation by repressing Nbwo activity at the protein level. We also found that mutations in the Nbwo woolly motif can prevent repression of NbWoV by NbCycB2, which results in a significant increase in the amount of active Nbwo proteins and in increases in trichome density and the number of branches. Our results reveal a novel reciprocal regulation mechanism between NbCycB2 and Nbwo during trichome formation in N. benthamiana.
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Affiliation(s)
- Min-Liang Wu
- Xiamen Key Laboratory for Plant Genetics, School of Life Sciences, Xiamen University, Xiamen, China
- FAFU-UCR Joint Center and Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yu-Chao Cui
- Xiamen Key Laboratory for Plant Genetics, School of Life Sciences, Xiamen University, Xiamen, China
| | - Li Ge
- Xiamen Key Laboratory for Plant Genetics, School of Life Sciences, Xiamen University, Xiamen, China
| | - Li-Peng Cui
- Xiamen Key Laboratory for Plant Genetics, School of Life Sciences, Xiamen University, Xiamen, China
| | - Zhi-Chao Xu
- Xiamen Key Laboratory for Plant Genetics, School of Life Sciences, Xiamen University, Xiamen, China
| | - Hong-Ying Zhang
- Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, China
| | - Zhao-Jun Wang
- Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, China
| | - Dan Zhou
- Xiamen Key Laboratory for Plant Genetics, School of Life Sciences, Xiamen University, Xiamen, China
| | - Shuang Wu
- FAFU-UCR Joint Center and Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Liang Chen
- Xiamen Key Laboratory for Plant Genetics, School of Life Sciences, Xiamen University, Xiamen, China
| | - Hong Cui
- Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, China
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Wei Z, Cheng Y, Zhou C, Li D, Gao X, Zhang S, Chen M. Genome-Wide Identification of Direct Targets of the TTG1-bHLH-MYB Complex in Regulating Trichome Formation and Flavonoid Accumulation in Arabidopsis Thaliana. Int J Mol Sci 2019; 20:ijms20205014. [PMID: 31658678 PMCID: PMC6829465 DOI: 10.3390/ijms20205014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 09/27/2019] [Accepted: 10/08/2019] [Indexed: 12/17/2022] Open
Abstract
Extensive studies have shown that the MBW complex consisting of three kinds of regulatory proteins, MYB and basic helix–loop–helix (bHLH) transcription factors and a WD40 repeat protein, TRANSPARENT TESTA GLABRA1 (TTG1), acts in concert to promote trichome formation and flavonoid accumulation in Arabidopsis thaliana. TTG1 functions as an essential activator in these two biological processes. However, direct downstream targets of the TTG1-dependent MBW complex have not yet been obtained in the two biological processes at the genome-wide level in A. thaliana. In the present study, we found, through RNA sequencing and quantitative real-time PCR analysis, that a great number of regulatory and structural genes involved in both trichome formation and flavonoid accumulation are significantly downregulated in the young shoots and expanding true leaves of ttg1-13 plants. Post-translational activation of a TTG1-glucocorticoid receptor fusion protein and chromatin immunoprecipitation assays demonstrated that these downregulated genes are directly or indirectly targeted by the TTG1-dependent MBW complex in vivo during trichome formation and flavonoid accumulation. These findings further extend our understanding of the role of TTG1-dependent MBW complex in the regulation of trichome formation and flavonoid accumulation in A. thaliana.
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Affiliation(s)
- Zelou Wei
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Yalong Cheng
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China.
- Qinling National Forest Ecosystem Research Station, Huoditang, Ningshan 711600, Shaanxi, China.
| | - Chenchen Zhou
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Dong Li
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Xin Gao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Shuoxin Zhang
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China.
- Qinling National Forest Ecosystem Research Station, Huoditang, Ningshan 711600, Shaanxi, China.
| | - Mingxun Chen
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
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Wang Y, Yu Y, Chen Q, Bai G, Gao W, Qu Y, Ni Z. Heterologous Expression of GbTCP4, a Class II TCP Transcription Factor, Regulates Trichome Formation and Root Hair Development in Arabidopsis. Genes (Basel) 2019; 10:E726. [PMID: 31546783 DOI: 10.3390/genes10090726] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/12/2019] [Accepted: 09/18/2019] [Indexed: 12/17/2022] Open
Abstract
Two class I family teosinte branched1/cycloidea/proliferating cell factor1 (TCP) proteins from allotetraploid cotton are involved in cotton fiber cell differentiation and elongation and root hair development. However, the biological function of most class II TCP proteins is unclear. This study sought to reveal the characteristics and functions of the sea-island cotton class II TCP gene GbTCP4 by biochemical, genetic, and molecular biology methods. GbTCP4 protein localizes to nuclei, binding two types of TCP-binding cis-acting elements, including the one in its promoter. Expression pattern analysis revealed that GbTCP4 is widely expressed in tissues, with the highest level in flowers. GbTCP4 is expressed at different fiber development stages and has high transcription in fibers beginning at 5 days post anthesis (DPA). GbTCP4 overexpression increases primary root hair length and density and leaf and stem trichomes in transgenic Arabidopsis relative to wild-type plants (WT). GbTCP4 binds directly to the CAPRICE (CPC) promoter, increasing CPC transcript levels in roots and reducing them in leaves. Compared with WT plants, lignin content in the stems of transgenic Arabidopsis overexpressing GbTCP4 increased, and AtCAD5 gene transcript levels increased. These results suggest that GbTCP4 regulates trichome formation and root hair development in Arabidopsis and may be a candidate gene for regulating cotton fiber elongation.
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Gao C, Guo Y, Wang J, Li D, Liu K, Qi S, Jin C, Duan S, Gong J, Li Z, Chen M. Brassica napusGLABRA3-1 promotes anthocyanin biosynthesis and trichome formation in true leaves when expressed in Arabidopsis thaliana. Plant Biol (Stuttg) 2018; 20:3-9. [PMID: 28940939 DOI: 10.1111/plb.12633] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 09/18/2017] [Indexed: 06/07/2023]
Abstract
Previous studies have shown that GLABRA3 (AtGL3), a bHLH transcription factor, plays essential roles in anthocyanin biosynthesis and trichome formation in Arabidopsis thaliana. However, there have been no such studies of a homologue, BnGL3, from the closely related crop, Brassica napus. Here, we analysed the BnGL3-1 coding domain sequence from the B. napus cultivar QINYOU Seven, identified conserved protein domains and performed a phylogenetic analysis to elucidate its relationship with homologues form a range of plant species. When expressed in tobacco leaves as a fusion protein with green fluorescent protein, BnGL3-1 accumulated in the nucleus, consistent with its predicted function as a transcription factor. Ectopic expression of the BnGL3-1 gene in the A. thaliana gl3-3 mutant resulted in levels of anthocyanins and numbers of trichomes in true leaves that were higher than in wild-type plants. Moreover, overexpression of BnGL3-1 in gl3-3 compensated for the promotion and repression of genes involved in anthocyanin biosynthesis and trichome formation, respectively, that has been reported in gl3-3 young shoots and expanding true leaves. This study provides new insights into GL3 function in anthocyanin biosynthesis and trichome formation in crucifers, and represents a promising target for genetic manipulation of B. napus.
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Affiliation(s)
- C Gao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - Y Guo
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - J Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - D Li
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - K Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - S Qi
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - C Jin
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - S Duan
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - J Gong
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - Z Li
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
| | - M Chen
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China
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Zhou L, Zheng K, Wang X, Tian H, Wang X, Wang S. Control of trichome formation in Arabidopsis by poplar single-repeat R3 MYB transcription factors. Front Plant Sci 2014; 5:262. [PMID: 24959169 PMCID: PMC4051193 DOI: 10.3389/fpls.2014.00262] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 05/21/2014] [Indexed: 05/18/2023]
Abstract
In Arabidopsis, trichome formation is regulated by the interplay of R3 MYBs and several others transcription factors including the WD40-repeat protein TRANSPARENT TESTA GLABRA1 (TTG1), the R2R3 MYB transcription factor GLABRA1 (GL1), the bHLH transcription factor GLABRA3 (GL3) or ENHANCER OF GLABRA3 (EGL3), and the homeodomain protein GLABRA2 (GL2). R3 MYBs including TRICHOMELESS1 (TCL1), TCL2, TRYPTICHON (TRY), CAPRICE (CPC), ENHANCER OF TRY AND CPC1 (ETC1), ETC2 and ETC3 negatively regulate trichome formation by competing with GL1 for binding GL3 or EGL3, thus blocking the formation of TTG1-GL3/EGL3-GL1, an activator complex required for the activation of the trichome positive regulator gene GL2. However, it is largely unknown if R3 MYBs in other plant species especially woody plants have similar functions. By BLASTing the Populus trichocarpa protein database using the entire amino acid sequence of TCL1, an Arabidopsis R3 MYB transcription factor, we identified a total of eight R3 MYB transcription factor genes in poplar, namely P. trichocarpa TRICHOMELESS1 through 8 (PtrTCL1-PtrTCL8). The amino acid signature required for interacting with bHLH transcription factors and the amino acids required for cell-to-cell movement of R3 MYBs are not fully conserved in all PtrTCLs. When tested in Arabidopsis protoplasts, however, all PtrTCLs interacted with GL3. Expressing each of the eight PtrTCL genes in Arabidopsis resulted in either glabrous phenotypes or plants with reduced trichome numbers, and expression levels of GL2 in all transgenic plants tested were greatly reduced. Expression of PtrTCL1 under the control of TCL1 native promoter almost completely complemented the mutant phenotype of tcl. In contrast, expression of PtrTCL1 under the control of TRY native promoter in the try mutant, or under the control of CPC native promoter in the cpc mutant resulted in glabrous phenotypes, suggesting that PtrTCL1 functions similarly to TCL1, but not TRY and CPC.
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Affiliation(s)
| | | | | | | | | | - Shucai Wang
- *Correspondence: Shucai Wang, Key Laboratory of Molecular Epigenetics of Ministry of Education and key Laboratory of Vegetation Ecology of Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024, China e-mail:
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