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辰山科研人员揭示了植物MKK基因家族新的扩张机制

【PDF原文: Comparative analysis of plant MKK gene family reveals novel expansion mechanism of the members and sheds new light on functional conservation

2018529日,《BMC Genomics》在线发表了上海辰山植物园(中国科院上海辰山植物科学研究中心)植物抗逆与分子进化(草种种质资源创新)研究组题为Comparative analysis of plant MKK gene family reveals novel expansion mechanism of the members and sheds new light on functional conservation的研究论文。该研究报道了植物MKK 基因家族在进化过程中存在两个独特的扩张机制,并在该家族的功能演化方面提出了新的观点。该论文的第一作者是蒋敏。

Abstract

Background: Mitogen-activated protein kinase (MAPK) cascades play critical functions in almost every aspect of plant growth and development, which regulates many physiological and biochemical processes. As a middle nodal point of the MAPK cascades, although evolutionary analysis of MKK from individual plant families had some reports,their evolutionary history in entire plants is still not clear.

Results: To better understand the evolution and function of plant MKKs, we performed systematical molecular evolutionary analysis of the MAPKK gene family and also surveyed their gene organizations, sequence features and expression patterns in different subfamilies. Phylogenetic analysis showed that plant MAPKK fall into five different groups (Group A–E). Majority orthology groups seemed to be a single or low-copy genes in all plant species analyzed in Group B, C and D, whereas group A MKKs undergo several duplication events, generating multiple gene copies. Further analysis showed that these duplication events were on account of whole genome duplications (WGDs) in plants and the duplicate genes maybe have undergone functional divergence. We also found that group E MKKs had mutation with one change of serine or theronine might lead to inactivity originated through the ancient tandem duplicates in monocots. Moreover, we also identified MKK3 integrated NTF2 domain that might have gradually lost the cytoplasmic-nuclear trafficking activity, which suggests that they may involve with the gene function more and more sophistication in the evolutionary process. Moreover, expression analyses
indicated that plant MKK genes play probable roles in UV-B signaling.

Conclusion: In general, ancient gene and genome duplications are significantly conducive to the expansion of the plant MKK gene family. Our study reveals two distinct evolutionary patterns for plant MKK proteins and sheds new light on the functional evolution of this gene family.

Keywords: MAPK kinase, Gene duplication, Evolution, Gene expression, NTF2 domain, Docking site

该研究系统分析了51种从单细胞到多细胞的单子叶和双子叶植物中MKK基因家族的进化历史,并调查了这些物种中MKK各个亚族的组成与序列特点以及在不同植物中的表达模式。结果显示,植物MAPKK基因家族可以分成A-E五个亚家族。大部分亚族在所有植物都比较保守,只含有1个或低拷贝基因。而在A亚族进化过程中出现过几次基因重复事件,导致了多基因拷贝的出现。进一步分析发现这些基因重复事件是由于植物整个基因组重复引起的。我们还发现因串联重复事件导致了E亚族在单子叶植物中出现了MKK基因的扩张,并伴有磷酸化位点S/T-X5-S/T中丝氨酸或苏氨酸碱基的突变,这些突变可能与MKK基因功能的演化相关。另外,BMKKMKK3)基因还含有一个NTF2功能结构域。此结构域是生物体内唯一可单独形成蛋白的蛋白质,介导RanGDP蛋白的核质转运。NTF2MKK3的进化分析显示出他们的整合主要发生在植物进化的早期,被子植物中并不存在这一现象。并且高等植物MKK3基因中的NTF2结构域的核质转运功能逐渐消失,这可能与植物基因在进化过程中表现出越来越精细的功能有关。此外,表达分析表明植物MKK基因可能在UV-B信号中起作用。

上海辰山植物园(中国科学院上海辰山植物科学研究中心)植物抗逆与分子进化研究组(组长:储昭庆 研究员)一直致力于研究进化过程中保守的抗逆基因在草种多重抗逆中的作用。课题组前期在冷季型草坪草模式植物二穗短柄草MAPK蛋白级联和其下游的转录因子及负调控基因家族的研究方面取得系统性研究成果,发表一区SCI论文1篇,二区SCI论文6篇,三区SCI论文2篇,申请发明专利两项 这些工作为筛选抗逆草种和提高草坪草抗逆性尤其是冷季型草坪草的耐热性提供了研究基础和理论依据,为进一步研究抗逆基因在草种中耐受极端生境中的作用机理,最终培育出抗逆性强,一年四季常绿,高耐受及高富集重金属等的草种以期对环境修复中加以应用等打下坚实的基础。

本研究得到了中科院种质资源创新项目(zszc-013)和上海市绿化和市容管理局项目(G162406G162407 )的支持。

 

 

【PDF原文: Comparative analysis of plant MKK gene family reveals novel expansion mechanism of the members and sheds new light on functional conservation

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