Department of Biological Sciences, The University of Memphis, Memphis, TN, USA.
Center for Biodiversity Research, The University of Memphis, Memphis, TN, USA.
J Hered. 2020 Dec 7;111(6):531-538. doi: 10.1093/jhered/esaa037.
Plant mitochondria and plastids display an array of inheritance patterns and varying levels of heteroplasmy, where individuals harbor more than 1 version of a mitochondrial or plastid genome. Organelle inheritance in plants has the potential to be quite complex and can vary with plant growth, development, and reproduction. Few studies have sought to investigate these complicated patterns of within-individual variation and inheritance using experimental crosses in plants. We carried out crosses in carrot, Daucus carota L. (Apiaceae), which has previously been shown to exhibit organellar heteroplasmy. We used mitochondrial and plastid markers to begin to disentangle the patterns of organellar inheritance and the fate of heteroplasmic variation, with special focus on cases where the mother displayed heteroplasmy. We also investigated heteroplasmy across the plant, assaying leaf samples at different development stages and ages. Mitochondrial and plastid paternal leakage was rare and offspring received remarkably similar heteroplasmic mixtures to their heteroplasmic mothers, indicating that heteroplasmy is maintained over the course of maternal inheritance. When offspring did differ from their mother, they were likely to exhibit a loss of the genetic variation that was present in their mother. Finally, we found that mitochondrial variation did not vary significantly over plant development, indicating that substantial vegetative sorting did not occur. Our study is one of the first to quantitatively investigate inheritance patterns and heteroplasmy in plants using controlled crosses, and we look forward to future studies making use of whole genome information to study the complex evolutionary dynamics of plant organellar genomes.
植物的线粒体和质体表现出一系列的遗传模式和不同程度的异质性，个体中存在着不止一种线粒体或质体基因组的版本。植物细胞器的遗传可能非常复杂，并且可能随植物的生长、发育和繁殖而变化。很少有研究试图通过植物的实验杂交来研究这些个体内变异和遗传的复杂模式。我们在胡萝卜（Daucus carota L.）中进行了杂交，胡萝卜先前被证明存在细胞器异质性。我们使用线粒体和质体标记物来开始理清细胞器遗传的模式和异质性变异的命运，特别关注表现出异质性的母亲。我们还研究了整个植物的异质性，分析了不同发育阶段和年龄的叶片样本。线粒体和质体的父系渗漏很少见，后代从他们异质性的母亲那里获得了非常相似的异质性混合物，这表明异质性在母系遗传过程中得以维持。当后代与母亲不同时，它们很可能会失去母亲体内存在的遗传变异。最后，我们发现线粒体的变异在植物发育过程中没有显著变化，这表明没有发生大量的营养生殖。我们的研究是首次使用控制杂交对植物的遗传模式和异质性进行定量研究的研究之一，我们期待未来的研究利用全基因组信息来研究植物细胞器基因组的复杂进化动态。
