Shedge Vikas, Arrieta-Montiel Maria, Christensen Alan C, Mackenzie Sally A
Plant Science Initiative, University of Nebraska, Lincoln, Nebraska 68588-0660, USA.
Plant Cell. 2007 Apr;19(4):1251-64. doi: 10.1105/tpc.106.048355. Epub 2007 Apr 27.
For >20 years, the enigmatic behavior of plant mitochondrial genomes has been well described but not well understood. Chimeric genes appear, and occasionally are differentially replicated or expressed, with significant effects on plant phenotype, most notably on male fertility, yet the mechanisms of DNA replication, chimera formation, and recombination have remained elusive. Using mutations in two important genes of mitochondrial DNA metabolism, we have observed reproducible asymmetric recombination events occurring at specific locations in the mitochondrial genome. Based on these experiments and existing models of double-strand break repair, we propose a model for plant mitochondrial DNA replication, chimeric gene formation, and the illegitimate recombination events that lead to stoichiometric changes. We also address the physiological and developmental effects of aberrant events in mitochondrial genome maintenance, showing that mitochondrial genome rearrangements, when controlled, influence plant reproduction, but when uncontrolled, lead to aberrant growth phenotypes and dramatic reduction of the cell cycle.
二十多年来，植物线粒体基因组的神秘行为已被充分描述，但尚未得到很好的理解。嵌合基因出现，偶尔会发生差异复制或表达，对植物表型有显著影响，最明显的是对雄性育性的影响，然而DNA复制、嵌合体形成和重组的机制仍然难以捉摸。利用线粒体DNA代谢的两个重要基因中的突变，我们观察到在线粒体基因组的特定位置发生了可重复的不对称重组事件。基于这些实验和现有的双链断裂修复模型，我们提出了一个关于植物线粒体DNA复制、嵌合基因形成以及导致化学计量变化的非法重组事件的模型。我们还探讨了线粒体基因组维持异常事件的生理和发育影响，表明线粒体基因组重排在受到控制时会影响植物繁殖，但不受控制时会导致异常生长表型和细胞周期的显著缩短。
