Mobile elements known as T-DNAs are transferred from pathogenic Agrobacterium to plants and reprogram the host cell to form hairy roots or tumors. Disarmed non-oncogenic T-DNAs are extensively used to deliver transgenes in plant genetic engineering. Such T-DNAs were the first known targets of RNA silencing mechanisms, which detect foreign RNA in plant cells and produce small RNAs that induce transcript degradation. These T-DNAs can also be transcriptionally silenced by the deposition of epigenetic marks such as DNA methylation and the dimethylation of lysine 9 (H3K9me2) in plants. Here, we review the targeting and the roles of RNA silencing and DNA methylation on T-DNAs in transgenic plants as well as during pathogenesis. In addition, we discuss the crosstalk between T-DNAs and genome-wide changes in DNA methylation during pathogenesis. We also cover recently discovered regulatory phenomena, such as T-DNA suppression and RNA silencing-independent and epigenetic-independent mechanisms that can silence T-DNAs. Finally, we discuss the implications of findings on T-DNA silencing for the improvement of plant genetic engineering.

中文翻译：

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转基因和发病机制中 T-DNA 的表观遗传学控制


称为 T-DNA 的移动元件从致病性农杆菌转移到植物，并重新编程宿主细胞以形成毛状根或肿瘤。解除武装的非致癌 T-DNA 广泛用于在植物基因工程中递送转基因。这种 T-DNA 是 RNA 沉默机制的第一个已知靶标，该机制检测植物细胞中的外源 RNA 并产生诱导转录本降解的小 RNA。这些 T-DNA 也可以通过植物中 DNA 甲基化和赖氨酸 9 （H3K9me2） 二甲基化等表观遗传标记的沉积而被转录沉默。在这里，我们回顾了 RNA 沉默和 DNA 甲基化对转基因植物中 T-DNA 的靶向和作用以及发病机制。此外，我们还讨论了 T-DNA 之间的串扰和发病机制中 DNA 甲基化的全基因组变化。我们还介绍了最近发现的调节现象，例如 T-DNA 抑制和可以沉默 T-DNA 的 RNA 非沉默性和表观遗传非依赖性机制。最后，我们讨论了 T-DNA 沉默研究结果对植物基因工程改进的影响。