细胞质雄性不育(CMS)源于细胞核和细胞质之间的不相容性,作为线粒体基因组(有丝分裂基因组)中嵌合结构的典型代表,已广泛应用于各种作物的杂交种子生产。导致CMS的嵌合线粒体基因的频繁出现与线粒体DNA(mtDNA)进化一致。由忠实的母系遗传引起的序列保守性和由频繁的序列重组引起的嵌合结构已被定义为有丝分裂基因组的两个主要特征。然而,这些嵌合线粒体基因何时以及如何在线粒体高度保守的繁殖中出现是一个谜。这次审查,因此,提出了植物CMS研究的批判性观点,以阐明这种现象的机制。一般来说,远缘杂交是在自然种群和育种中产生原始CMS来源的主要机制。线粒体和有丝分裂基因组在生命周期的关键阶段表现出多形性和动态变化。在种子吸收过程中,干燥种子中的线粒体原发育成功能完整的线粒体,随着mtDNA结构和数量的变化,在萌发阶段出现大量线粒体或有丝分裂体融合和裂变。有丝分裂基因组的稳定性由核基因座控制,如核基因Msh1。其抑制导致mtDNA的重排和可遗传的CMS基因的产生。mtDNA的大量重组也经常在远缘杂种和体细胞/杂种杂种中发现。由于mtDNA重组在远距离杂交中普遍存在,我们提出了一个假设,即原始CMS基因起源于远距离杂交产生的杂种种子萌发过程中的mtDNA重组,以解决种子萌发过程中异基因核基因组引起的核质不相容性。
Cytoplasmic male sterility (CMS) arises from the incompatibility between the nucleus and cytoplasm as typical representatives of the chimeric structures in the mitochondrial genome (mitogenome), which has been extensively applied for hybrid seed production in various crops. The frequent occurrence of chimeric mitochondrial genes leading to CMS is consistent with the mitochondrial DNA (mtDNA) evolution. The sequence conservation resulting from faithfully maternal inheritance and the chimeric structure caused by frequent sequence recombination have been defined as two major features of the mitogenome. However, when and how these chimeric mitochondrial genes appear in the context of the highly conserved reproduction of mitochondria is an enigma. This
review, therefore, presents the critical view of the research on CMS in plants to elucidate the mechanisms of this phenomenon. Generally, distant hybridization is the main mechanism to generate an original CMS source in natural populations and in breeding. Mitochondria and mitogenomes show pleomorphic and dynamic changes at key stages of the life cycle. The promitochondria in dry seeds develop into fully functioning mitochondria during seed imbibition, followed by massive mitochondria or mitogenome fusion and fission in the germination stage along with changes in the mtDNA structure and quantity. The mitogenome stability is controlled by nuclear loci, such as the nuclear gene Msh1. Its suppression leads to the rearrangement of mtDNA and the production of heritable CMS genes. An abundant recombination of mtDNA is also often found in distant hybrids and somatic/cybrid hybrids. Since mtDNA recombination is ubiquitous in distant hybridization, we put forward a hypothesis that the original CMS genes originated from mtDNA recombination during the germination of the hybrid seeds produced from distant hybridizations to solve the nucleo-cytoplasmic incompatibility resulting from the allogenic nuclear genome during seed germination.