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Luiza Atella A, Fatima Grossi-de-Sá M, Alves-Ferreira M. Cotton promoters for controlled gene expression. ELECTRON J BIOTECHN 2023. [DOI: 10.1016/j.ejbt.2022.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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Liu R, Long Q, Zou X, Wang Y, Pei Y. DNA methylation occurring in Cre-expressing cells inhibits loxP recombination and silences loxP-sandwiched genes. THE NEW PHYTOLOGIST 2021; 231:210-224. [PMID: 33742463 DOI: 10.1111/nph.17353] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 03/12/2021] [Indexed: 06/12/2023]
Abstract
The low DNA recombination efficiency of site-specific recombinase systems in plants limits their application; however, the underlying mechanism is unknown. We evaluate the gene deletion performance of four recombinase systems (Cre/loxP, Flp/FRT, KD/KDRT and B3/B3RT) in tobacco where the recombinases are under the control of germline-specific promoters. We find that the expression of these recombinases results mostly in gene silencing rather than gene deletion. Using the Cre/loxP system as a model, we reveal that the region flanked by loxP sites (floxed) is hypermethylated, which prevents floxed genes from deletion while silencing the expression of the genes. We further show CG methylation alone in the recombinase binding element of the loxP site is unable to impede gene deletion; instead, CHH methylation in the crossover region is required to inhibit loxP recombination. Our study illustrates the important role of recombinase-induced DNA methylation in the inhibition of site-specific DNA recombination and uncovers the mechanism underlying recombinase-associated gene silence in plants.
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Affiliation(s)
- Ruochen Liu
- Chongqing Key Laboratory of Application and Safety Control of Genetically Modified Crops; Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, China
| | - Qin Long
- Chongqing Key Laboratory of Application and Safety Control of Genetically Modified Crops; Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, China
| | - Xiuping Zou
- Chongqing Key Laboratory of Application and Safety Control of Genetically Modified Crops; Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, China
| | - You Wang
- Chongqing Key Laboratory of Application and Safety Control of Genetically Modified Crops; Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, China
| | - Yan Pei
- Chongqing Key Laboratory of Application and Safety Control of Genetically Modified Crops; Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Beibei, Chongqing, 400715, China
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Ma M, Chen X, Yin Y, Fan R, Li B, Zhan Y, Zeng F. DNA Methylation Silences Exogenous Gene Expression in Transgenic Birch Progeny. FRONTIERS IN PLANT SCIENCE 2020; 11:523748. [PMID: 33414793 PMCID: PMC7783445 DOI: 10.3389/fpls.2020.523748] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 10/28/2020] [Indexed: 05/04/2023]
Abstract
The genetic stability of exogenous genes in the progeny of transgenic trees is extremely important in forest breeding; however, it remains largely unclear. We selected transgenic birch (Betula platyphylla) and its hybrid F1 progeny to investigate the expression stability and silencing mechanism of exogenous genes. We found that the exogenous genes of transgenic birch could be transmitted to their offspring through sexual reproduction. The exogenous genes were segregated during genetic transmission. The hybrid progeny of transgenic birch WT1×TP22 (184) and WT1×TP23 (212) showed higher Bgt expression and greater insect resistance than their parents. However, the hybrid progeny of transgenic birch TP23×TP49 (196) showed much lower Bgt expression, which was only 13.5% of the expression in its parents. To elucidate the mechanism underlying the variation in gene expression between the parents and progeny, we analyzed the methylation rates of Bgt in its promoter and coding regions. The hybrid progeny with normally expressed exogenous genes showed much lower methylation rates (0-29%) than the hybrid progeny with silenced exogenous genes (32.35-45.95%). These results suggest that transgene silencing in the progeny is mainly due to DNA methylation at cytosine residues. We further demonstrated that methylation in the promoter region, rather than in the coding region, leads to gene silencing. We also investigated the relative expression levels of three methyltransferase genes: BpCMT, BpDRM, and BpMET. The transgenic birch line 196 with a silenced Gus gene showed, respectively, 2.54, 9.92, and 4.54 times higher expression levels of BpCMT, BpDRM, and BpMET than its parents. These trends are consistent with and corroborate the high methylation levels of exogenous genes in the transgenic birch line 196. Therefore, our study suggests that DNA methylation in the promoter region leads to silencing of exogenous genes in transgenic progeny of birch.
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Affiliation(s)
- Minghao Ma
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin, China
- College of Life Science, Northeast Forestry University, Harbin, China
| | - Xiaohui Chen
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin, China
- College of Life Science, Northeast Forestry University, Harbin, China
| | - Yibo Yin
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin, China
- College of Life Science, Northeast Forestry University, Harbin, China
| | - Ruixin Fan
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin, China
- College of Life Science, Northeast Forestry University, Harbin, China
| | - Bo Li
- College of Life Science, Northeast Forestry University, Harbin, China
| | - Yaguang Zhan
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin, China
- College of Life Science, Northeast Forestry University, Harbin, China
| | - Fansuo Zeng
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin, China
- College of Life Science, Northeast Forestry University, Harbin, China
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