Transposition favors the generation of large effect mutations that may facilitate rapid adaption

First author: Leandro Quadrana; Affiliations: PSL Research University (巴黎文理研究大学): Paris, France

Corresponding author: Vincent Colot

Transposable elements (TEs) are mobile parasitic sequences that have been repeatedly coopted during evolution to generate new functions and rewire gene regulatory networks. Yet, the contribution of active TEs to the creation of heritable mutations remains unknown. Using TE accumulation lines in Arabidopsis thaliana we show that once initiated, transposition produces an exponential spread of TE copies, which rapidly leads to high mutation rates. Most insertions occur near or within genes and targets differ between TE families. Furthermore, we uncover an essential role of the histone variant H2A.Z in the preferential integration of Ty1/copia retrotransposons within environmentally responsive genes and away from essential genes. We also show that epigenetic silencing of new Ty1/copia copies can affect their impact on major fitness-related traits, including flowering time. Our findings demonstrate that TEs are potent episodic (epi)mutagens that, thanks to marked chromatin tropisms, limit the mutation load and increase the potential for rapid adaptation.

转座元件TE是一段可移动的“寄生”序列，其在演化过程中不断的被增补，以产生新的功能并更新基因调控网络。然而，活性TE对于可遗传突变的创新的具体作用还不清楚。利用拟南芥中的TE积累株系，作者的研究显示一旦起始，转位并会导致TE拷贝呈指数级的扩散，最终导致基因组的高突变率。大多数插入发生在基因附近或者基因内部，并且不同的TE家族靶向的基因组区域各有不同。此外，作者发现组蛋白变体H2A.Z在Ty1/copia逆转座子整合到环境响应相关基因，而远离必需基因的过程中发挥重要作用。作者还发现将新的Ty1/copia拷贝进行表观沉默能够影响其对于主要适应性相关性状的作用，其中就包括开花时间。本文的研究揭示了TE是潜在的偶发性表观或非表观突变诱因，并且由于明显的染色质的向性，限制了突变负荷并增加了物种快速适应的潜力。

通讯：Vincent Colot (https://www.ibens.ens.fr/spip.php?rubrique37&lang=en)

个人简介：法国巴黎国家农学研究所，硕士；英国剑桥植物育种研究所，博士。

研究方向：基于染色质的表观进程对于可遗传的表型变异的作用。

doi: https://doi.org/10.1038/s41467-019-11385-5

Journal: Nature Communications

Published date: July 31, 2019