Molecular Evolution of VEF-Domain-Containing PcG Genes in Plants
Molecular Evolution of VEF-Domain-Containing PcG Genes in Plants
复制标题
DOI：
10.1093/mp/ssp032
复制
发表时间：
2009-07-01
期刊：
影响因子：
27.5
通讯作者：
Sung, Z. Renee
中科院分区：
文献类型：
--
作者：
Chen, Ling-Jing;Diao, Zhao-Yan;Sung, Z. Renee
拟南芥春化2 (VRN2)、胚胎花2 (EMF2) 和受精独立种子2 (FIS2) 分别参与春化介导的开花、营养发育和种子发育。它们与拟南芥 VEF-L36 共享一个在植物和动物中保守的 VEF 结构域。为了研究含 VEF 结构域的基因（VEF 基因）的进化，我们分析了陆地植物中与 VEF 基因相关的序列。迄今为止，已鉴定出来自 11 个被子植物科的 24 个全长序列和来自另外 9 个科的 54 个部分序列。大多数已鉴定的全长序列与拟南芥 EMF2 具有最大的序列相似性，并具有相同的主要结构域结构。 EMF2样序列不仅广泛存在于被子植物中，而且还存在于裸子植物、石松植物和苔藓的基因组序列中。除了拟南芥以外，没有从植物中回收到类似 FIS2 或 VEF-L36 的序列，包括已对全基因组进行测序的水稻和杨树。全长序列的系统发育分析表明，密切相关类群的 EMF2 同源物中氨基酸序列具有高度保守性。 VRN2 同源物作为一个进化枝嵌套在较大的 EMF2 进化枝内。 FIS2 和 VEF-L36 在 VRN2 进化枝中恢复。 VRN2 进化枝可能是在 Eurosid I 和 Eurosid II 谱系分化之前从 Rosids 中发生的 EMF2 重复事件进化而来的。我们认为基因组进化的动态变化有助于含有 VEF 结构域的基因家族的产生。仅对 VEF 结构域进行系统发育分析表明，VEF 序列在 EMF2/VRN2 分歧后根据物种关系继续进化。动物和陆地植物中 EMF2 样序列的存在表明，EMF2 的原型形式在植物和动物谱系分化之前就已经存在。基于整个被子植物的结构域组织和中间序列的出现，提出的事件序列可以解释 VRN2 从类似 EMF2 的祖先序列进化而来，可能是在祖先 EMF2 复制之后。现有数据进一步表明 VEF-L36 和 FIS2 源自 VRN2 样祖先序列。因此，基因组中VEF-L36和FIS2的存在可能最终取决于VRN2样序列的存在。
Arabidopsis VERNALIZATION2 (VRN2), EMBRYONIC FLOWER2 (EMF2), and FERTILIZATION-INDEPENDENT SEED2 (FIS2) are involved in vernalization-mediated flowering, vegetative development, and seed development, respectively. Together with Arabidopsis VEF-L36, they share a VEF domain that is conserved in plants and animals. To investigate the evolution of VEF-domain-containing genes (VEF genes), we analyzed sequences related to VEF genes across land plants. To date, 24 full-length sequences from 11 angiosperm families and 54 partial sequences from another nine families were identified. The majority of the full-length sequences identified share greatest sequence similarity with and possess the same major domain structure as Arabidopsis EMF2. EMF2-like sequences are not only widespread among angiosperms, but are also found in genomic sequences of gymnosperms, lycophyte, and moss. No FIS2- or VEF-L36-like sequences were recovered from plants other than Arabidopsis, including from rice and poplar for which whole genomes have been sequenced. Phylogenetic analysis of the full-length sequences showed a high degree of amino acid sequence conservation in EMF2 homologs of closely related taxa. VRN2 homologs are recovered as a clade nested within the larger EMF2 clade. FIS2 and VEF-L36 are recovered in the VRN2 clade. VRN2 clade may have evolved from an EMF2 duplication event that occurred in the rosids prior to the divergence of the eurosid I and eurosid II lineages. We propose that dynamic changes in genome evolution contribute to the generation of the family of VEF-domain-containing genes. Phylogenetic analysis of the VEF domain alone showed that VEF sequences continue to evolve following EMF2/VRN2 divergence in accordance with species relationship. Existence of EMF2-like sequences in animals and across land plants suggests that a prototype form of EMF2 was present prior to the divergence of the plant and animal lineages. A proposed sequence of events, based on domain organization and occurrence of intermediate sequences throughout angiosperms, could explain VRN2 evolution from an EMF2-like ancestral sequence, possibly following duplication of the ancestral EMF2. Available data further suggest that VEF-L36 and FIS2 were derived from a VRN2-like ancestral sequence. Thus, the presence of VEF-L36 and FIS2 in a genome may ultimately be dependent upon the presence of a VRN2-like sequence.