Copy numbers of mitochondrial genes change during melon leaf development and are lower than the numbers of mitochondria
Copy numbers of mitochondrial genes change during melon leaf development and are lower than the numbers of mitochondria
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瓜叶发育过程中线粒体基因拷贝数发生变化，低于线粒体数
DOI：
10.1038/s41438-019-0177-8
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发表时间：
2019-08-11
影响因子：
8.7
通讯作者：
Shou, Weisong
中科院分区：
文献类型：
--
作者：
Shen, Jia;Zhang, Yuejian;Shou, Weisong
甜瓜是研究线粒体遗传学的有用植物物种，因为它包含所有植物物种中最大的和结构多样的线粒体基因组之一，并且经历线粒体的父系传递。我们使用液滴数字（dd）PCR结合流式细胞仪测定细胞核DNA的数量，以确定在甜瓜叶片发育的四个阶段的四个线粒体基因（nad 9，rps 1，matR和atp 6）的绝对每细胞拷贝数。这些线粒体基因的拷贝数不仅在叶片发育过程中变化，而且彼此之间也存在差异，并且线粒体基因的拷贝数与其转录水平之间没有相关性。基因拷贝数从约36.8 +/- 4.5（第15叶中的atp 6拷贝）变化至约82.9 +/- 5.7（第9叶中的nad 9拷贝），而线粒体的平均数在第15叶中约为416.6 +/- 182.7，在第9叶中约为459.1 +/- 228.2。这些观察结果表明，甜瓜的叶细胞不包含足够的线粒体基因拷贝，以确保每个线粒体拥有整个线粒体基因组。鉴于这一细胞学证据，我们的研究结果表明，线粒体DNA在甜瓜作为一个亚基因组分子，而不是作为一个单一的主循环，个别线粒体基因的拷贝数可能会有很大的差异。对控制亚基因组mtDNA分子的相对流行和传播的分子机制的更好理解应该提供对线粒体基因组跨代连续性的见解。
Melon is a useful plant species for studying mitochondrial genetics because it contains one of the largest and structurally diverse mitochondrial genomes among all plant species and undergoes paternal transmission of mitochondria. We used droplet digital (dd) PCR in combination with flow cytometric determination of nuclear DNA quantities to determine the absolute per-cell copy numbers of four mitochondrial genes (nad9, rps1, matR, and atp6) across four stages of melon leaf development. The copy numbers of these mitochondrial genes not only varied during leaf development but also differed among each other, and there was no correlation between the copy numbers of the mitochondrial genes and their transcript levels. The gene copy numbers varied from approximately 36.8 +/- 4.5 (atp6 copies in the 15th leaf) to approximately 82.9 +/- 5.7 (nad9 copies in the 9th leaf), while the mean number of mitochondria was approximately 416.6 +/- 182.7 in the 15th leaf and 459.1 +/- 228.2 in the 9th leaf. These observations indicate that the leaf cells of melon do not contain sufficient copies of mitochondrial genes to ensure that every mitochondrion possesses the entire mitochondrial genome. Given this cytological evidence, our results indicate that mtDNA in melon exists as a sub-genomic molecule rather than as a single-master circle and that the copy numbers of individual mitochondrial genes may vary greatly. An improved understanding of the molecular mechanism(s) controlling the relative prevalence and transmission of sub-genomic mtDNA molecules should provide insights into the continuity of the mitochondrial genome across generations.