Comparative Plastome Analysis of Root- and Stem-Feeding Parasites of Santalales Untangle the Footprints of Feeding Mode and Lifestyle Transitions
Comparative Plastome Analysis of Root- and Stem-Feeding Parasites of Santalales Untangle the Footprints of Feeding Mode and Lifestyle Transitions
复制标题
DOI：
10.1093/gbe/evz271
复制
发表时间：
2020-01-01
影响因子：
3.3
通讯作者：
Liu, Huan
中科院分区：
文献类型：
--
作者：
Chen, Xiaoli;Fang, Dongming;Liu, Huan
在植物中，寄生触发质体基因组（质体）的还原进化。为了解开其他植物在地下或地上和一般过渡兼性专性寄生之间的分子进化关联，我们分析了34个完整的质体的自养，根和茎喂养半寄生，全寄生檀香目。我们观察到无法解释的损失管家基因和tRNA的半寄生虫和戏剧性的基因组重构全寄生Balanophoraceae，其质体有异常低的GC含量。基因组的变化主要与半寄生或全寄生的进化有关，而从根到茎的喂养模式的转变没有发挥重要作用。相反，从自养生物到根-然后是茎-取食寄生物，分子进化的速率以逐步的方式加速。祖先向根寄生的过渡已经与质体中选择的放松相一致。另一个显着的质体基因的选择性转变发生的茎饲养者的演变，这表明这种衍生形式与营养专业化，尽管保留光合能力。寄生Santalales填补了我们对寄生虫相关质体变性的理解的空白。我们发现，生活方式基因组协会展开相互依赖的营养专业化和喂养模式的转变，全寄生Balanophoraceae提供了一个系统，探索功能领域的质体。
In plants, parasitism triggers the reductive evolution of plastid genomes (plastomes). To disentangle the molecular evolutionary associations between feeding on other plants below- or aboveground and general transitions from facultative to obligate parasitism, we analyzed 34 complete plastomes of autotrophic, root- and stem-feeding hemiparasitic, and holoparasitic Santalales. We observed inexplicable losses of housekeeping genes and tRNAs in hemiparasites and dramatic genomic reconfiguration in holoparasitic Balanophoraceae, whose plastomes have exceptionally low GC contents. Genomic changes are related primarily to the evolution of hemi- or holoparasitism, whereas the transition from a root- to a stem-feeding mode plays no major role. In contrast, the rate of molecular evolution accelerates in a stepwise manner from autotrophs to root- and then stem-feeding parasites. Already the ancestral transition to root-parasitism coincides with a relaxation of selection in plastomes. Another significant selectional shift in plastid genes occurs as stem-feeders evolve, suggesting that this derived form coincides with trophic specialization despite the retention of photosynthetic capacity. Parasitic Santalales fill a gap in our understanding of parasitism-associated plastome degeneration. We reveal that lifestyle-genome associations unfold interdependently over trophic specialization and feeding mode transitions, where holoparasitic Balanophoraceae provide a system for exploring the functional realms of plastomes.