The evolution of apomixis in autopolyploid alpine plants

同源多倍体高山植物无融合生殖的进化

• 批准号: 222251156
• 负责人: Professorin Dr. Elvira Hörandl
• 金额: --
• 依托单位: Abteilung Systematik, Biodiversität und Evolution der Planzen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/222251156?language=en
• 关键词: evolution; apomixis; autopolyploid; alpine; plants

The origin of apomixis in natural populations is still not well understood. Apomixis is often associated to to occurrence in colder climates. Here we want to test hypotheses that low temperature has a direct effect on origin of apomixis by triggering unreduced egg cell formation in diploids. Unreduced female gamete formation can lead to polyploidization via a female triploid bridge, and coupling to parthenogenesis will result in fully functional apomictic seed formation. Polyploidy, on the other hand, is probably associated to adaptive features to colder climates like alpine dwarf growth. We suppose that DNA methylation profiles play a major role for both spontaneous shifts in mode of reproduction of the same genotype, and for rapid adaptations to environmental conditions. In pre-projects, we studied the mode of reproduction and ecological niche differentiation of the alpine diploid-autotetraploid system Ranunculus kuepferi in natural populations of the Alps. We observed a significant niche shift towards low temperatures in facultative tetraploid populations, low frequencies of apomixis in diploids but predominance of apomixis in tetraploids, and a temperature dependence of mode of reproduction. Low genetic divergence between cytotypes suggested involvement of epigenetic control mechanisms. In the present project we want to test experimentally in climate growth chambers the following hypotheses: 1) stability of cold-induced apomictic seed formation in diploid and autotetraploid plants in reciprocal temperature treatments (measured quantitatively via flow cytometric seed screening), 2) apomixis in diploids as the first step towards polyploidization via a female triploid bridge, while male unreduced gamete formation is less important (flow cytometric seed screening and pollen ploidy); 4) tetraploids can reduce their growth under cold treatments better than diploids by reducing cell numbers, and are more frost-tolerant; 5) DNA methylation variation is temperature-dependent and differs between ploidy levels, apomictic/sexual plants and growth syndromes; for this task we will compare patterns of methylation-sensitive AFLPs in experimental reciprocal treatments to the patterns in the wild, and correlate to mode of reproduction / ploidy / growth. The project will help to entangle effects of mode of reproduction and of polyploidy for the evolution of apomicts. The emergence of apomixis is thought to happen on diploid level as a consequence of cold treatments, while polyploidization would have the effect of establishing the respective populations in colder climates. A combination of endogenous selection for apomictic seed formation and exogenous selection for cold-adapted polyploid genotypes resulted in the predominance of apomictic polyploids in higher altitudes of the Alps.

自然群体中无融合生殖的起源至今仍不清楚。无融合生殖通常发生在寒冷的气候中。在这里，我们要测试的假设，低温有一个直接影响的起源无融合生殖触发未减少卵细胞形成二倍体。未减数的雌配子形成可以通过雌三倍体桥导致多倍化，并且与孤雌生殖偶联将导致完全功能的无融合生殖种子形成。另一方面，多倍性可能与适应寒冷气候的特征有关，如高山侏儒生长。我们假设DNA甲基化谱在同一基因型的繁殖模式的自发转变和对环境条件的快速适应中起着重要作用。在前期项目中，我们研究了阿尔卑斯山自然种群中高山二倍体-同源四倍体系统毛茛的繁殖模式和生态位分化。我们观察到一个显着的生态位向低温的兼性四倍体种群，二倍体无融合生殖的频率低，但优势的无融合生殖在四倍体，和温度依赖性的繁殖模式。细胞型之间的遗传差异低，表明参与表观遗传控制机制。在本项目中，我们希望在气候生长室中对以下假设进行实验测试：1）二倍体和同源四倍体植物在温度交互处理中冷诱导无融合生殖种子形成的稳定性（通过流式细胞术种子筛选定量测量），2）二倍体中的无融合生殖作为通过雌性三倍体桥实现多倍化的第一步，而雄性未减数配子的形成不太重要（4）四倍体比二倍体能更好地抑制低温处理下的生长，减少细胞数量，且更耐霜冻; 5）DNA甲基化变异是温度依赖性的，并且在倍性水平、无融合生殖/有性植物和生长综合征之间不同;对于这项任务，我们将比较实验性相互处理中甲基化敏感性AFLP的模式与野生模式，并与繁殖/倍性/生长模式相关。该项目将有助于纠缠的影响，繁殖方式和多倍体的进化无融合生殖。无融合生殖的出现被认为是在二倍体水平上发生的，作为冷处理的结果，而多倍化将具有在较冷的气候中建立各自种群的效果。 无融合生殖种子形成的内源选择和冷适应多倍体基因型的外源选择相结合，导致无融合生殖多倍体在阿尔卑斯山的高海拔地区的优势。

项目成果

Correlations of polyploidy and apomixis with elevation and associated environmental gradients in an alpine plant

• DOI: 10.1093/aobpla/plw064
• 发表时间: 2016-10
• 期刊: AoB Plants
• 影响因子: 2.9
• 作者: Christoph C. F. Schinkel;Bernhard Kirchheimer;A. Dellinger;Simone Klatt;M. Winkler;S. Dullinger;E. Hörandl

Epigenetic Patterns and Geographical Parthenogenesis in the Alpine Plant Species Ranunculus kuepferi (Ranunculaceae)

• DOI: 10.3390/ijms21093318
• 发表时间: 2020-05
• 期刊: International Journal of Molecular Sciences
• 影响因子: 5.6
• 作者: Christoph C. F. Schinkel;E. Syngelaki;Bernhard Kirchheimer;S. Dullinger;Simone Klatt;E. Hörandl

Effects of Temperature Treatments on Cytosine-Methylation Profiles of Diploid and Autotetraploid Plants of the Alpine Species Ranunculus kuepferi (Ranunculaceae)

• DOI: 10.3389/fpls.2020.00435
• 发表时间: 2020-04
• 期刊: Frontiers in Plant Science
• 影响因子: 5.6
• 作者: E. Syngelaki;Christoph C. F. Schinkel;Simone Klatt;E. Hörandl