Gene Function Rather than Reproductive Mode Drives the Evolution of RNA Helicases in Sexual and Apomictic Boechera
Gene Function Rather than Reproductive Mode Drives the Evolution of RNA Helicases in Sexual and Apomictic Boechera
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DOI：
10.1093/gbe/evaa078
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发表时间：
2020-04
影响因子：
3.3
通讯作者：
M. Kiefer;Berit H Nauerth;Christopher Volkert;D. Ibberson;Anna Loreth;A. Schmidt
中科院分区：
文献类型：
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作者：
M. Kiefer;Berit H Nauerth;Christopher Volkert;D. Ibberson;Anna Loreth;A. Schmidt
摘要在高等植物中，通过种子进行有性生殖和无性生殖（无融合生殖）已成为一种可供选择的策略。导致两种生殖模式共存的进化优势目前还没有得到很好的理解。预期有害突变的积累导致群体中无融合生殖谱系的快速消除。在这条线，无融合生殖起源反复，可能从性途径的失调，导致生殖谱系（生殖系）的发展与有性植物相比，无融合生殖的改变。这可能涉及控制生殖的基因突变。越来越多的证据表明，RNA解旋酶是生殖细胞发育的重要调节因子。为了深入了解这个多样化基因家族的58个成员在有性和无融合生殖植物中的进化，我们采用了靶富集与下一代测序相结合的方法来鉴定来自24种Boechera属的等位基因变体，包括有性、兼性和专性无融合生殖体。有趣的是，来自无融合生殖体的等位基因变体并没有显示出持续增加的突变频率。无论是序列高度保守的任何加入，或等位基因变异体优先窝藏在进化保守性较低的C-和N-末端结构域的突变，或提出高突变负荷独立的生殖模式。只有少数基因的等位基因变异携带有害的突变，只确定在无融合生殖体。为了测试高序列保守性是否与基本细胞或发育过程中的作用相关，我们分析了拟南芥VASA-LIKE（VASL）突变株系，并确定了胚珠和生殖发育过程中的多效性缺陷。这表明，在无融合生殖体中，选择机制也是基于基因功能的。
Abstract In higher plants, sexual and asexual reproductions through seeds (apomixis) have evolved as alternative strategies. Evolutionary advantages leading to coexistence of both reproductive modes are currently not well understood. It is expected that accumulation of deleterious mutations leads to a rapid elimination of apomictic lineages from populations. In this line, apomixis originated repeatedly, likely from deregulation of the sexual pathway, leading to alterations in the development of reproductive lineages (germlines) in apomicts as compared with sexual plants. This potentially involves mutations in genes controlling reproduction. Increasing evidence suggests that RNA helicases are crucial regulators of germline development. To gain insights into the evolution of 58 members of this diverse gene family in sexual and apomictic plants, we applied target enrichment combined with next-generation sequencing to identify allelic variants from 24 accessions of the genus Boechera, comprising sexual, facultative, and obligate apomicts. Interestingly, allelic variants from apomicts did not show consistently increased mutation frequency. Either sequences were highly conserved in any accession, or allelic variants preferentially harbored mutations in evolutionary less conserved C- and N-terminal domains, or presented high mutation load independent of the reproductive mode. Only for a few genes allelic variants harboring deleterious mutations were only identified in apomicts. To test if high sequence conservation correlates with roles in fundamental cellular or developmental processes, we analyzed Arabidopsis thaliana mutant lines in VASA-LIKE (VASL), and identified pleiotropic defects during ovule and reproductive development. This indicates that also in apomicts mechanisms of selection are in place based on gene function.