Massive intracellular gene transfer during plastid genome reduction in nongreen Orobanchaceae
Massive intracellular gene transfer during plastid genome reduction in nongreen Orobanchaceae
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DOI：
10.1111/nph.13784
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发表时间：
2016-04-01
期刊：
影响因子：
9.4
通讯作者：
Wicke, Susann
中科院分区：
文献类型：
--
作者：
Cusimano, Natalie;Wicke, Susann
非光合作用植物的质体基因组经历了广泛的基因丢失和分子进化速率的加速。在这里，我们推断的机制和时间的简化基因组进化下放松选择列当科。我们分析了几种寄生虫的质体，主要集中在列当属使用基因组描述和贝叶斯遗传学比较方法。除此之外，我们还扫描了寄生虫的其他细胞基因组，以追踪从其质体中清除的所有基因的命运。我们的分析表明，第一个功能基因的损失发生在10Myr的过渡到专性寄生列当科，和物理质体减少收益的小缺失，随着时间的推移积累。进化速率的变化与在broomrapes的基因组还原过程相吻合，这表明从光合作用到其他分子过程的选择性限制的转移改变了质体速率平衡。大多数与光合作用相关的基因或基因片段从肉苁蓉质体中丢失，由于多次胞内转移和随后的片段化，这些基因或基因片段在它们的核或线粒体基因组中存活。我们的研究结果表明，非必需的DNA在非光合寄生虫的质体中比在其他细胞基因组中被消除得更快。
Plastid genomes (plastomes) of nonphotosynthetic plants experience extensive gene losses and an acceleration of molecular evolutionary rates. Here, we inferred the mechanisms and timing of reductive genome evolution under relaxed selection in the broomrape family (Orobanchaceae). We analyzed the plastomes of several parasites with a major focus on the genus Orobanche using genome-descriptive and Bayesian phylogenetic-comparative methods. Besides this, we scanned the parasites' other cellular genomes to trace the fate of all genes that were purged from their plastomes. Our analyses indicate that the first functional gene losses occurred within 10Myr of the transition to obligate parasitism in Orobanchaceae, and that the physical plastome reduction proceeds by small deletions that accumulate over time. Evolutionary rate shifts coincide with the genomic reduction process in broomrapes, suggesting that the shift of selectional constraints away from photosynthesis to other molecular processes alters the plastid rate equilibrium. Most of the photosynthesis-related genes or fragments of genes lost from the plastomes of broomrapes have survived in their nuclear or mitochondrial genomes as the results of multiple intracellular transfers and subsequent fragmentation. Our findings indicate that nonessential DNA is eliminated much faster in the plastomes of nonphotosynthetic parasites than in their other cellular genomes.