线粒体基因组的高突变负荷及其单亲遗传和高多倍体有利于维持种群内的有害突变。细胞如何组成和适应不利的线粒体等位基因的积累仍不清楚。大多数有害的变化可能通过净化选择来纠正,然而,线粒体和核编码基因产物之间的紧密合作为补偿性适应性变化提供了理论潜力.在植物中,细胞质雄性不育是核-线粒体共适应情况的已知例子,其中核编码的育性恢复(Rf)基因进化以抵消线粒体编码的细胞质雄性不育(CMS)基因的影响并恢复育性。大多数克隆的Rfs属于一个小的单系组,拟南芥中包含26个五肽重复基因,称为Rf-like(RFL)。在这个分析中,我们探索了拟南芥RFL基因的功能多样性,发现RFL8基因与CMS抑制无关,但对植物胚胎发育至关重要。体外拯救的rfl8小植株缺乏线粒体血红素裂解酶复合物的产生。完整的分子和遗传分析使我们能够证明,已选择RFL8基因来允许线粒体ccmFN2基因的翻译,该基因编码源自ccmFN基因分裂的血红素裂解酶复合物亚基,特别是在十字花科植物中。因此,这项研究代表了对植物中谱系特异性线粒体基因组重排的核补偿的清楚案例,并证明了可以响应CMS抑制以外的其他线粒体偏差来选择RFL基因。
The high mutational load of mitochondrial genomes combined with their uniparental inheritance and high polyploidy favors the maintenance of deleterious mutations within populations. How cells compose and adapt to the accumulation of disadvantageous mitochondrial alleles remains unclear. Most harmful changes are likely corrected by purifying selection, however, the intimate collaboration between mitochondria- and nuclear-encoded gene products offers theoretical potential for compensatory adaptive changes. In plants, cytoplasmic male sterilities are known examples of nucleo-mitochondrial coadaptation situations in which nuclear-encoded restorer of fertility (Rf) genes evolve to counteract the effect of mitochondria-encoded cytoplasmic male sterility (CMS) genes and restore fertility. Most cloned Rfs belong to a small monophyletic group, comprising 26 pentatricopeptide repeat genes in Arabidopsis, called Rf-like (RFL). In this analysis, we explored the functional diversity of RFL genes in Arabidopsis and found that the RFL8 gene is not related to CMS suppression but essential for plant embryo development. In vitro-rescued rfl8 plantlets are deficient in the production of the mitochondrial heme-lyase complex. A complete ensemble of molecular and genetic analyses allowed us to demonstrate that the RFL8 gene has been selected to permit the translation of the mitochondrial ccmFN2 gene encoding a heme-lyase complex subunit which derives from the split of the ccmFN gene, specifically in Brassicaceae plants. This study represents thus a clear
case of nuclear compensation to a lineage-specific mitochondrial genomic rearrangement in plants and demonstrates that RFL genes can be selected in response to other mitochondrial deviancies than CMS suppression.