Khanna Harjeet K, Paul Jean-Yves, Harding Robert M, Dickman Martin B, Dale James L
Institute of Health and Biomedical Innovation, Queensland University of Technology, 2 George St., Brisbane Queensland, 4001, Australia.
Mol Plant Microbe Interact. 2007 Sep;20(9):1048-54. doi: 10.1094/MPMI-20-9-1048.
The death of plant cells in culture following exposure to Agrobacterium tumefaciens remains a major obstacle in developing Agrobacterium-mediated transformation into a highly efficient genotype-independent technology. Here, we present evidence that A. tumefaciens exposure induces cell death in banana cell suspensions. More than 90% of embryogenic banana cells died after exposure to A. tumefaciens and cell death was accompanied by a subset of features associated with apoptosis in mammalian cells, including DNA laddering, fragmentation, and formation of apoptotic-like bodies. Importantly, these cellular responses were inhibited in cells expressing the animal antiapoptosis genes Bcl-xL, Bcl-2 3' untranslated region, and CED-9. Inhibition of cell death resulted in up to 90% of cell clumps transformed with Bcl-xL, a 100-fold enhancement over vector controls, approaching the transformation and regeneration of every "transformable" cell. Similar results using sugarcane, a crop plant known for recalcitrance to Agrobacterium transformation, suggest that antiapoptosis genes may inhibit these phenomena and increase the transformation frequency of many recalcitrant plant species, including the major monocot cereal crop plants. Evidence of inhibition of plant cell death by cross-kingdom antiapoptotic genes also contributes to the growing evidence that genes for control of programmed cell death are conserved across wide evolutionary distances, even though these mechanisms are not well understood in plants.
暴露于根癌农杆菌后培养的植物细胞死亡，仍然是将根癌农杆菌介导的转化发展成为一种高效的不依赖基因型的技术的主要障碍。在此，我们提供证据表明，暴露于根癌农杆菌会诱导香蕉细胞悬浮液中的细胞死亡。超过90%的胚性香蕉细胞在暴露于根癌农杆菌后死亡，并且细胞死亡伴随着与哺乳动物细胞凋亡相关的一系列特征，包括DNA梯状条带、片段化以及凋亡小体的形成。重要的是，在表达动物抗凋亡基因Bcl-xL、Bcl-2 3'非翻译区和CED-9的细胞中，这些细胞反应受到抑制。细胞死亡的抑制导致用Bcl-xL转化的细胞团高达90%，比载体对照提高了100倍，接近每个“可转化”细胞的转化和再生。使用甘蔗（一种已知对根癌农杆菌转化具有抗性的作物）获得的类似结果表明，抗凋亡基因可能抑制这些现象，并提高许多难转化植物物种的转化频率，包括主要的单子叶谷类作物。跨物种抗凋亡基因抑制植物细胞死亡的证据也进一步证明，尽管植物中程序性细胞死亡的机制尚未完全了解，但控制程序性细胞死亡的基因在广泛的进化距离上是保守的。
