Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, Albrecht-Thaer-Weg 6, 14195 Berlin, Germany.
Thuenen Institute of Forest Genetics, Sieker Landstraße 2, 22927 Großhansdorf, Germany.
Int J Mol Sci. 2022 Jul 28;23(15):8321. doi: 10.3390/ijms23158321.
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 ) or of a gene encoding a constitutively active cytokinin receptor variant (). Both genes are derived from and were expressed in poplar trees under the control of their own promoter or the cambium-specific promoter. - and -expressing plants were smaller than wild-type plants and formed more lateral branches; transgenic plants additionally showed an increased stem diameter. In contrast, - and -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 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 as a novel gene to enhance biomass formation in woody plants.
形成层分生组织负责木本植物的树皮和木材形成。形成层分生组织的活性受各种因素控制；其中之一是植物激素细胞分裂素。在这里，我们通过异位表达具有增强活性的细胞分裂素生物合成基因（命名为）或编码组成型激活的细胞分裂素受体变体的基因（），探索了不同的方法来遗传工程化杨树植物的形成层活性。这两个基因均来自玉米，在自身启动子或形成层特异性启动子的控制下在杨树中表达。与野生型植物相比，-和-表达的植物更小，形成更多的侧枝；转基因植物还表现出茎直径增加。相比之下，-和-表达的植物比野生型植物长得更高，分枝模式没有改变，形成更多的形成层细胞，导致径向茎生长增加。在次生韧皮部细胞或形成层细胞中表达时的有效性与细胞分裂素在调节形成层活性中的双重、组织自主和非自主活性一致。我们提出作为一种新的基因，以增强木本植物的生物量形成。
