DNA Methylation Silences Exogenous Gene Expression in Transgenic Birch Progeny
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 e...
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| Format: | Article |
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Frontiers Media S.A.
2020-12-01
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| Series: | Frontiers in Plant Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fpls.2020.523748/full |
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| author | Minghao Ma Minghao Ma Xiaohui Chen Xiaohui Chen Yibo Yin Yibo Yin Ruixin Fan Ruixin Fan Bo Li Yaguang Zhan Yaguang Zhan Fansuo Zeng Fansuo Zeng |
| author_facet | Minghao Ma Minghao Ma Xiaohui Chen Xiaohui Chen Yibo Yin Yibo Yin Ruixin Fan Ruixin Fan Bo Li Yaguang Zhan Yaguang Zhan Fansuo Zeng Fansuo Zeng |
| author_sort | Minghao Ma |
| collection | DOAJ |
| description | 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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| institution | Directory Open Access Journal |
| issn | 1664-462X |
| language | English |
| last_indexed | 2024-12-20T03:23:42Z |
| publishDate | 2020-12-01 |
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| spelling | doaj.art-ac0874a1e88e422bb1d48fdf327d9af22022-12-21T19:55:10ZengFrontiers Media S.A.Frontiers in Plant Science1664-462X2020-12-011110.3389/fpls.2020.523748523748DNA Methylation Silences Exogenous Gene Expression in Transgenic Birch ProgenyMinghao Ma0Minghao Ma1Xiaohui Chen2Xiaohui Chen3Yibo Yin4Yibo Yin5Ruixin Fan6Ruixin Fan7Bo Li8Yaguang Zhan9Yaguang Zhan10Fansuo Zeng11Fansuo Zeng12Key Laboratory of Saline-Alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin, ChinaCollege of Life Science, Northeast Forestry University, Harbin, ChinaKey Laboratory of Saline-Alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin, ChinaCollege of Life Science, Northeast Forestry University, Harbin, ChinaKey Laboratory of Saline-Alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin, ChinaCollege of Life Science, Northeast Forestry University, Harbin, ChinaKey Laboratory of Saline-Alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin, ChinaCollege of Life Science, Northeast Forestry University, Harbin, ChinaCollege of Life Science, Northeast Forestry University, Harbin, ChinaKey Laboratory of Saline-Alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin, ChinaCollege of Life Science, Northeast Forestry University, Harbin, ChinaKey Laboratory of Saline-Alkali Vegetation Ecology Restoration (Northeast Forestry University), Ministry of Education, Harbin, ChinaCollege of Life Science, Northeast Forestry University, Harbin, ChinaThe 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.https://www.frontiersin.org/articles/10.3389/fpls.2020.523748/fulltransgenic Betula platyphyllagenetic stabilitygenetically modified silencingDNA methylationinsect resistance |
| spellingShingle | Minghao Ma Minghao Ma Xiaohui Chen Xiaohui Chen Yibo Yin Yibo Yin Ruixin Fan Ruixin Fan Bo Li Yaguang Zhan Yaguang Zhan Fansuo Zeng Fansuo Zeng DNA Methylation Silences Exogenous Gene Expression in Transgenic Birch Progeny Frontiers in Plant Science transgenic Betula platyphylla genetic stability genetically modified silencing DNA methylation insect resistance |
| title | DNA Methylation Silences Exogenous Gene Expression in Transgenic Birch Progeny |
| title_full | DNA Methylation Silences Exogenous Gene Expression in Transgenic Birch Progeny |
| title_fullStr | DNA Methylation Silences Exogenous Gene Expression in Transgenic Birch Progeny |
| title_full_unstemmed | DNA Methylation Silences Exogenous Gene Expression in Transgenic Birch Progeny |
| title_short | DNA Methylation Silences Exogenous Gene Expression in Transgenic Birch Progeny |
| title_sort | dna methylation silences exogenous gene expression in transgenic birch progeny |
| topic | transgenic Betula platyphylla genetic stability genetically modified silencing DNA methylation insect resistance |
| url | https://www.frontiersin.org/articles/10.3389/fpls.2020.523748/full |
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