Stoichiometric Shifting of the Plant Mitochondrial Genome

植物线粒体基因组进化出了影响其结构和表达的几个显著特征。其中之一是维持亚基因组DNA分子在显著不同的拷贝数。利用蚕豆细胞质雄性不育系统，研究植物线粒体基因组中拷贝数的基因组转移和亚化学计量DNA分子的保留现象。该奖项将支持两名研究生完成本课题两个领域的博士论文研究。第一部分将研究线粒体基因组迁移的生理意义，包括迁移对交叉相容性的影响、温度对迁移过程的影响，以及线粒体基因组免受迁移保护的植物组织。第二名学生将研究线粒体不育序列pvs-orf239的表达及其对转移过程的影响。这将包括将ORF239产品从线粒体出口到细胞外周的研究；这些特殊的研究将在用pvs-orf239序列转化的酵母中进行。这些研究，通过利用普通豆类系统的特殊特征，解决了与所有高等植物相关的生物现象，并应为植物线粒体基因型的定向操作提供策略。

The plant mitochondrial genome has evolved several distinguishing features that influence its structure and expression. One of these is the maintenance of subgenomic DNA molecules at markedly different copy numbers. The phenomenon of genomic shifts in copy number and the retention of substoichiometric DNA molecules within the plant mitochondrial genome will be investigated using the cytoplasmic male sterility system in common bean. This award will support two graduate students to complete their Ph.D. thesis research in two areas of this topic. The first will investigate the physiological implications of genomic shifts in the mitochondrial genome by examining the effects of shifting on cross-compatibility, the influence of temperature on the shifting process, and the plant tissues in which the mitochondrial genome is protected from shifting. The second student will investigate the expression of the mitochondrial sterility sequence, pvs-orf239, and its influence on the shifting process. This will include investigation of the export of the ORF239 product from the mitochondrion to the periphery of the cell; these particular studies will be carried out in yeast transformed with the pvs-orf239 sequence.These investigations, through taking advantage of features special to the common bean system, address biological phenomena relevant to all higher plants, and should provide strategies for directed manipulation of the plant mitochondrial genotype.