Gohlke Jochen, Deeken Rosalia
School of Plant Sciences, University of Arizona Tucson, AZ, USA.
Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, University of Wuerzburg Wuerzburg, Germany.
Front Plant Sci. 2014 Apr 23;5:155. doi: 10.3389/fpls.2014.00155. eCollection 2014.
Agrobacterium tumefaciens causes crown gall disease on various plant species by introducing its T-DNA into the genome. Therefore, Agrobacterium has been extensively studied both as a pathogen and an important biotechnological tool. The infection process involves the transfer of T-DNA and virulence proteins into the plant cell. At that time the gene expression patterns of host plants differ depending on the Agrobacterium strain, plant species and cell-type used. Later on, integration of the T-DNA into the plant host genome, expression of the encoded oncogenes, and increase in phytohormone levels induce a fundamental reprogramming of the transformed cells. This results in their proliferation and finally formation of plant tumors. The process of reprogramming is accompanied by altered gene expression, morphology and metabolism. In addition to changes in the transcriptome and metabolome, further genome-wide ("omic") approaches have recently deepened our understanding of the genetic and epigenetic basis of crown gall tumor formation. This review summarizes the current knowledge about plant responses in the course of tumor development. Special emphasis is placed on the connection between epigenetic, transcriptomic, metabolomic, and morphological changes in the developing tumor. These changes not only result in abnormally proliferating host cells with a heterotrophic and transport-dependent metabolism, but also cause differentiation and serve as mechanisms to balance pathogen defense and adapt to abiotic stress conditions, thereby allowing the coexistence of the crown gall and host plant.
根癌土壤杆菌通过将其T-DNA导入基因组，在多种植物物种上引发冠瘿病。因此，根癌土壤杆菌作为病原体和重要的生物技术工具都得到了广泛研究。感染过程涉及T-DNA和毒力蛋白转移到植物细胞中。此时，宿主植物的基因表达模式因根癌土壤杆菌菌株、植物物种和所用细胞类型的不同而有所差异。随后，T-DNA整合到植物宿主基因组中，编码的致癌基因表达，以及植物激素水平的升高会诱导转化细胞发生根本性的重编程。这导致它们增殖并最终形成植物肿瘤。重编程过程伴随着基因表达、形态和代谢的改变。除了转录组和代谢组的变化外，最近全基因组（“组学”）方法进一步加深了我们对冠瘿肿瘤形成的遗传和表观遗传基础的理解。本综述总结了目前关于肿瘤发育过程中植物反应的知识。特别强调了发育中的肿瘤中表观遗传、转录组、代谢组和形态变化之间的联系。这些变化不仅导致宿主细胞异常增殖，具有异养和运输依赖型代谢，还会引起分化，并作为平衡病原体防御和适应非生物胁迫条件的机制，从而使冠瘿和宿主植物能够共存。
