Lempe Janne, Moser Mirko, Asquini Elisa, Si-Ammour Azeddine, Flachowsky Henryk
Julius Kühn Institute (JKI), Federal Research Centre for Cultivated Plants, Institute for Breeding Research on Fruit Crops, Dresden, Germany.
Research and Innovation Centre, Fondazione Edmund Mach (FEM), San Michele all'Adige, TN, Italy.
Front Plant Sci. 2024 Jul 15;15:1433865. doi: 10.3389/fpls.2024.1433865. eCollection 2024.
Over the course of the year, temperate trees experience extremes in temperature and day length. In order to protect themselves from frost damage in winter, they enter a dormant state with no visible growth where all leaves are shed and buds are dormant. Also the young floral tissues need to withstand harsh winter conditions, as temperature fruit trees like apple develop their flower buds in the previous year of fruit development. So far, the genetic control of induction and release of dormancy is not fully understood. However, the transcription factor family of genes plays a major role in the control of winter dormancy. One of these genes is . This gene is expressed in the early phase of bud dormancy, but little is known about its function. Six transgenic apple lines were produced to study the function of in apple. For plant transformation, the binary plasmid vector p9oN-35s-MdDAM4 was used that contains the coding sequence of driven by the 35S promoter. Transgenicity of the lines was proven by PCR and southern hybridization. Based on siRNA sequencing and phenotypic observations, it was concluded that line M2024 overexpresses whereas the gene is silenced in all other lines. Phenotyping of the transgenic lines provided evidence that the overexpression of leads to an earlier induction and a later release of dormancy. Silencing this gene had exactly the opposite effects and thereby led to an increased duration of the vegetation period. Expression experiments revealed genes that were either potentially repressed or activated by . Among the potentially suppressed genes were several homologs of the (), five homologs, and several expansins, which may indicate a link between and the control of leaf senescence. Among the potentially activated genes is , which is in line with observed expression patterns during winter dormancy. , which shows little expression during endodormancy also appears to be activated by . Overall, this study provides experimental evidence with transgenic apple trees for being an important regulator of the onset of bud dormancy in apple.
在一年的时间里，温带树木经历温度和日照长度的极端变化。为了在冬季保护自己免受冻害，它们进入一种没有可见生长的休眠状态，所有叶子脱落，芽休眠。此外，幼嫩的花组织需要抵御严酷的冬季条件，因为像苹果这样的温带果树在前一年果实发育时就形成花芽。到目前为止，休眠诱导和解除的遗传控制尚未完全了解。然而，基因的转录因子家族在冬季休眠控制中起主要作用。其中一个基因是 。该基因在芽休眠早期表达，但对其功能了解甚少。为了研究 在苹果中的功能，构建了六个转基因苹果株系。对于植物转化，使用了二元质粒载体p9oN - 35s - MdDAM4，其包含由35S启动子驱动的 的编码序列。通过PCR和Southern杂交证明了株系的转基因性。基于siRNA测序和表型观察，得出结论：M2024株系过表达 ，而该基因在所有其他株系中沉默。转基因株系的表型分析提供了证据，表明 的过表达导致休眠更早诱导和更晚解除。沉默该基因产生了完全相反的效果，从而导致营养生长期延长。表达实验揭示了可能被 抑制或激活的基因。在可能被抑制的基因中，有几个 （）的同源物、五个 同源物和几个扩展蛋白，这可能表明 与叶片衰老控制之间存在联系。在可能被激活的基因中，有 ，这与冬季休眠期间观察到的表达模式一致。在内休眠期间几乎不表达的 似乎也被 激活。总体而言，本研究利用转基因苹果树提供了实验证据，证明 是苹果芽休眠起始的重要调节因子。
