Center for Plant Science Innovation, University of Nebraska, Lincoln, NE.
School of Biological Sciences, University of Nebraska, Lincoln, NE.
Mol Biol Evol. 2020 Jun 1;37(6):1615-1620. doi: 10.1093/molbev/msaa029.
Hundreds of plant mitogenomes have been sequenced from angiosperms, but relatively few mitogenomes are available from its sister lineage, gymnosperms. To examine mitogenomic diversity among extant gymnosperms, we generated draft mitogenomes from 11 diverse species and compared them with four previously published mitogenomes. Examined mitogenomes from Pinaceae and cycads retained all 41 protein genes and 26 introns present in the common ancestor of seed plants, whereas gnetophyte and cupressophyte mitogenomes experienced extensive gene and intron loss. In Pinaceae and cupressophyte mitogenomes, an unprecedented number of exons are distantly dispersed, requiring trans-splicing of 50-70% of mitochondrial introns to generate mature transcripts. RNAseq data confirm trans-splicing of these dispersed exons in Pinus. The prevalence of trans-splicing in vascular plant lineages with recombinogenic mitogenomes suggests that genomic rearrangement is the primary cause of shifts from cis- to trans-splicing in plant mitochondria.
已从被子植物中测序了数百个植物线粒体基因组，但来自其姐妹谱系裸子植物的线粒体基因组相对较少。为了研究现存裸子植物的线粒体基因组多样性，我们从 11 个不同的物种中生成了线粒体基因组草图，并将其与之前发表的四个线粒体基因组进行了比较。研究发现，松科和苏铁类植物的线粒体基因组保留了种子植物共同祖先中存在的所有 41 个蛋白质基因和 26 个内含子，而买麻藤和柏科植物的线粒体基因组经历了广泛的基因和内含子丢失。在松科和柏科植物的线粒体基因组中，出现了前所未有的大量外显子分散，需要对 50-70%的线粒体内含子进行反式剪接，以生成成熟的转录本。RNAseq 数据证实了 Pinus 中转录本的反式剪接。在具有重组性线粒体基因组的维管植物谱系中，反式剪接的普遍性表明基因组重排是植物线粒体中从顺式到反式剪接转变的主要原因。
