A Constitutively Active Cytokinin Receptor Variant Increases Cambial Activity and Stem Growth in Poplar
The cambial meristem is responsible for bark and wood formation in woody plants. The activity of the cambial meristem is controlled by various factors; one of them is the plant hormone cytokinin. Here, we have explored different approaches to genetically engineering cambial activity in poplar plants...
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MDPI AG
2022-07-01
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| author | Michael Riefler Tobias Brügmann Matthias Fladung Thomas Schmülling |
| author_facet | Michael Riefler Tobias Brügmann Matthias Fladung Thomas Schmülling |
| author_sort | Michael Riefler |
| collection | DOAJ |
| description | The cambial meristem is responsible for bark and wood formation in woody plants. The activity of the cambial meristem is controlled by various factors; one of them is the plant hormone cytokinin. Here, we have explored different approaches to genetically engineering cambial activity in poplar plants by the ectopic expression of a cytokinin biosynthesis gene with enhanced activity (named <i>ROCK4</i>) or of a gene encoding a constitutively active cytokinin receptor variant (<i>ROCK3</i>). Both genes are derived from <i>Arabidopsis thaliana</i> and were expressed in poplar trees under the control of their own promoter or the cambium-specific <i>pHB8</i> promoter. <i>pIPT3:ROCK4</i>- and <i>pHB8:ROCK4</i>-expressing plants were smaller than wild-type plants and formed more lateral branches; <i>pHB8:ROCK4</i> transgenic plants additionally showed an increased stem diameter. In contrast, <i>pAHK3</i><i>:ROCK3</i>- and <i>pHB8</i><i>:ROCK3</i>-expressing plants grew taller than wild type without an altered branching pattern and formed more cambial cells, leading to increased radial stem growth. The effectivity of <i>ROCK3</i> when expressed in either secondary phloem cells or in cambial cells is consistent with a dual, tissue-autonomous and non-autonomous activity of cytokinin in regulating cambial activity. We propose <i>ROCK3</i> as a novel gene to enhance biomass formation in woody plants. |
| first_indexed | 2024-03-09T05:22:37Z |
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| institution | Directory Open Access Journal |
| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-09T05:22:37Z |
| publishDate | 2022-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | International Journal of Molecular Sciences |
| spelling | doaj.art-d37083a9651042dd949aed061805c26c2023-12-03T12:39:55ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672022-07-012315832110.3390/ijms23158321A Constitutively Active Cytokinin Receptor Variant Increases Cambial Activity and Stem Growth in PoplarMichael Riefler0Tobias Brügmann1Matthias Fladung2Thomas Schmülling3Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, Albrecht-Thaer-Weg 6, 14195 Berlin, GermanyThuenen Institute of Forest Genetics, Sieker Landstraße 2, 22927 Großhansdorf, GermanyThuenen Institute of Forest Genetics, Sieker Landstraße 2, 22927 Großhansdorf, GermanyInstitute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, Albrecht-Thaer-Weg 6, 14195 Berlin, GermanyThe cambial meristem is responsible for bark and wood formation in woody plants. The activity of the cambial meristem is controlled by various factors; one of them is the plant hormone cytokinin. Here, we have explored different approaches to genetically engineering cambial activity in poplar plants by the ectopic expression of a cytokinin biosynthesis gene with enhanced activity (named <i>ROCK4</i>) or of a gene encoding a constitutively active cytokinin receptor variant (<i>ROCK3</i>). Both genes are derived from <i>Arabidopsis thaliana</i> and were expressed in poplar trees under the control of their own promoter or the cambium-specific <i>pHB8</i> promoter. <i>pIPT3:ROCK4</i>- and <i>pHB8:ROCK4</i>-expressing plants were smaller than wild-type plants and formed more lateral branches; <i>pHB8:ROCK4</i> transgenic plants additionally showed an increased stem diameter. In contrast, <i>pAHK3</i><i>:ROCK3</i>- and <i>pHB8</i><i>:ROCK3</i>-expressing plants grew taller than wild type without an altered branching pattern and formed more cambial cells, leading to increased radial stem growth. The effectivity of <i>ROCK3</i> when expressed in either secondary phloem cells or in cambial cells is consistent with a dual, tissue-autonomous and non-autonomous activity of cytokinin in regulating cambial activity. We propose <i>ROCK3</i> as a novel gene to enhance biomass formation in woody plants.https://www.mdpi.com/1422-0067/23/15/8321biomasscambiumcytokininpoplarplant growth |
| spellingShingle | Michael Riefler Tobias Brügmann Matthias Fladung Thomas Schmülling A Constitutively Active Cytokinin Receptor Variant Increases Cambial Activity and Stem Growth in Poplar International Journal of Molecular Sciences biomass cambium cytokinin poplar plant growth |
| title | A Constitutively Active Cytokinin Receptor Variant Increases Cambial Activity and Stem Growth in Poplar |
| title_full | A Constitutively Active Cytokinin Receptor Variant Increases Cambial Activity and Stem Growth in Poplar |
| title_fullStr | A Constitutively Active Cytokinin Receptor Variant Increases Cambial Activity and Stem Growth in Poplar |
| title_full_unstemmed | A Constitutively Active Cytokinin Receptor Variant Increases Cambial Activity and Stem Growth in Poplar |
| title_short | A Constitutively Active Cytokinin Receptor Variant Increases Cambial Activity and Stem Growth in Poplar |
| title_sort | constitutively active cytokinin receptor variant increases cambial activity and stem growth in poplar |
| topic | biomass cambium cytokinin poplar plant growth |
| url | https://www.mdpi.com/1422-0067/23/15/8321 |
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