Best Corinne, Mizrahi Ron, Ostersetzer-Biran Oren
Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus-Givat Ram, Jerusalem 9190401, Israel.
Plants (Basel). 2020 May 8;9(5):598. doi: 10.3390/plants9050598.
Mitochondria play key roles in cellular-energy metabolism and are vital for plant-life, such as for successful germination and early-seedling establishment. Most mitochondria contain their own genetic system (mtDNA, mitogenome), with an intrinsic protein-synthesis machinery. Although the challenges of maintaining prokaryotic-type structures and functions are common to Eukarya, land plants possess some of the most complex organelle composition of all known organisms. Angiosperms mtDNAs are characteristically the largest and least gene-dense among the eukaryotes. They often contain highly-variable intergenic regions of endogenous or foreign origins and undergo frequent recombination events, which result in different mtDNA configurations, even between closely-related species. The expression of the mitogenome in angiosperms involves extensive mtRNA processing steps, including numerous editing and splicing events. ? The answer to this remains a matter of speculation. We propose that this complexity may have arisen throughout the terrestrialization of plants, as a means to control embryonic mitochondrial functions -a critical adaptive trait to optimize seed germination. The unique characteristics of plant mtDNA may play pivotal roles in the nuclear-regulation of organellar biogenesis and metabolism, possibly to control embryos quiescence or dormancy, essential determinants for the establishment of viable plantlets that can survive post-germination.
线粒体在细胞能量代谢中发挥关键作用，对植物生命至关重要，例如对于成功萌发和早期幼苗形成。大多数线粒体含有自己的遗传系统（线粒体DNA，线粒体基因组），具有内在的蛋白质合成机制。尽管维持原核生物类型的结构和功能面临的挑战在真核生物中很常见，但陆地植物拥有所有已知生物中一些最复杂的细胞器组成。被子植物的线粒体DNA在真核生物中通常是最大且基因密度最低的。它们通常包含内源性或外源性的高度可变基因间区域，并经历频繁的重组事件，这导致即使在亲缘关系密切的物种之间也存在不同的线粒体DNA构型。被子植物中线粒体基因组的表达涉及广泛的线粒体RNA加工步骤，包括大量的编辑和剪接事件。 对此的答案仍然是一个推测的问题。我们认为这种复杂性可能在植物陆地化过程中出现，作为控制胚胎线粒体功能的一种手段——这是优化种子萌发的关键适应性特征。植物线粒体DNA的独特特征可能在细胞器生物发生和代谢的核调节中发挥关键作用，可能是为了控制胚胎的静止或休眠，这是建立能够在萌发后存活的有活力幼苗的重要决定因素。
