野大豆种群转座子和转录因子的多样性和分子适应

doi:10.17521/cjpe.2007.0121

摘要/Abstract

摘要：

对环境变化的适应机理一直是进化生物学和生态学长期争论的核心课题。根据适应逆境的生态学和分子生理的最新进展,设想逆境诱导转座子的转座,影响转录因子的表达,随即改变一系列抗性基因的表达水平,抗性种群快速适应形成;由此可能建立一个统一的进化理论。从黄河入海口野生大豆(Glycine soja)盐渍种群植株DNA扩增到一段干旱应答元件结合蛋白基因(DREB)序列,称为GsDREB1。克隆了一个全长的类Gypsy逆转录转座子整合酶基因序列,称为GsINT。种群内各植株该序列有多个拷贝,植株间存在限制片段长度多态性。根据所得的这两个序列,设计并合成包括GsINT 5'上游保守序列的Gs-1等若干引物,试图检测野大豆基因组中GsDREB1的5'上游是否存在逆转录转座子整合酶序列。将GsDREB1标记为探针,Southern杂交表明用Gs-1为正向引物GmDR1为逆向引物所扩增的产物既是多拷贝而又与GsDREB1高度同源。这一对引物扩增和部分测序的结果暗示逆转录转座子有的插入DREB的5'上游,种群内外植株间显现两基因间隔长度的多样性。据此提出抗性种群形成即适应进化分子机理的下列假说。正常种群主要由非抗性普通植株组成。当环境发生变化处于逆境条件时,种群内植株转座频率大大增加。转座子非定向地插入基因组。多数突变中性,不影响表型。少数插入到转录因子的5'上游或其编码区,可促进或阻抑其表达,由此引发转录因子所控制的抗性基因网络表达的增加或减少,抗性相应增加或降低。总的结果是在短时间内就能积累包括高抗性植株在内的有各种抗性水平的个体;对逆境敏感的个体不断地被自然选择所淘汰,但逆境不断诱导其产生,少数植株有可能利用逆境减弱的较短时间完成发育得以生存下来。此假说可以解释逆境条件下的植物种群为什么能快速形成而有更高的遗传多样性;又为什么抗性种群在高抗性植株产生的同时有时存在敏感植株。逆境促进的转座改变转录因子基因表达可能是植物生理和形态快速进化的一般分子机理。

关键词: 野大豆, 逆转录转座子, 转录因子, 逆境, 分子适应

Abstract:

Aims Elucidation of the molecular mechanism of local adaptation to changing environments represents a central goal in evolutionary biology and ecology. Formation of adaptive populations probably involves activation or repression of pre-existing tolerant genes by transcription factors (TFs) and retrotransposons under stress. Research in this area can lead toward to a unified theory of evolution.

Methods The consensus sequence of drought responsive element binding protein (DREB) from the wild soybean (Glycine soja) in Yellow River delta has been cloned, sequenced, and called GsDREB1. An integrase gene of Gypsy-like retrotransposon called GsINT was also cloned from G. soja. Southern hybridization indicated that GsINT consisted of multiple copies and showed restriction fragment length polymorphism among individuals in salinity populations. From both sequences of GsINT and GsDREB1, other pairs of primers were designed for amplification of 5'upstream of GsDREB1 in order to see if partial sequence of GsINT was inserted. Results indicated multiple copies of space sequence between INT and DREB and its diversity among individuals of plants within each population. Gene cloning and sequencing of amplified products showed possible existence of GsINT sequence in 5' upstream of GsDREB1.

Important findings Results led to a hypothesis on the origin of tolerant populations, i.e., a molecular mechanism on adaptive evolution of plants. In normal conditions, plant populations mainly contain non-tolerant individuals. Under stress conditions, retrotransposons increase their frequency of transposition. Most mutants are neutral without phenotypical change. Few insertions located into 5' upstream of transcriptional factors will change intensity of TFs' expression. Then a series of pre-existed stress responsive genes controlled by TFs will simultaneously change their rates of gene expression, resulting in formation of more tolerant or sensitive individuals. Individuals with high stress tolerance may appear by accumulation of several tolerant inserts step by step. As a result of complicated interaction among genes, plants with different levels of stress tolerance occur quickly under stress. By means of natural selection, stress-sensitive plants are lost under stress conditions; however, stress itself continuously creates new sensitive individuals. Few of them with a short life cycle may survive by using a short period time of weakened stress. This hypothesis explains that tolerant populations quickly form because transposition frequency under stress becomes very high. It also explains why tolerant populations contain higher genetic diversity and why a few stress-sensitive individuals exist under stress conditions.

Key words: wild soybean (Glycine soja), retrotransposon, transcription factor, stress, molecular adaptation

胡志昂, 姜国强, 邓馨, 王洪新. 野大豆种群转座子和转录因子的多样性和分子适应. 植物生态学报, 2007, 31(5): 952-959. DOI: 10.17521/cjpe.2007.0121

HU Zhi-Ang, JIANG Guo-Qiang, DENG Xin, WANG Hong-Xin. MOLECULAR ADAPTATION THROUGH DIVERSITY OF RETROTRANSPOSONS AND TRANSCRIPTIONAL FACTORS IN POPULATIONS OF WILD SOYBEAN (GLYCINE SOJA). Chinese Journal of Plant Ecology, 2007, 31(5): 952-959. DOI: 10.17521/cjpe.2007.0121

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2007.0121

https://www.plant-ecology.com/CN/Y2007/V31/I5/952

图/表 7

图1 野大豆类Gypsy逆转录转座子的整合酶基因GsINT碱基序列下划线部分为编码区 Underline part is the coding sequence of GsINT 加深部分为保守区,用于设计正向引物Gs-1来扩增INT与DREB1之间的序列 Bold part is the partial consensus domain used to amplify sequences between GsINT and GsDREB1

Fig.1 Sequence of integrase gene(GsINT) of Gypsy-like retrotransposon from Glycine soja

图2 野大豆第3种群部分植株整合酶基因INT的EcoRI酶切片段长度多样性

Fig.2 EcoRI restriction fragment length polymorphism of GsINT among plants of population 3 of Glycine soja

图3 野大豆DREB保守序列GsDREB1的碱基序列

Fig.3 Sequence of consensus sequence of DREB from Glycine soja

图4 野大豆各种DREB和整合酶基因引物及两者间的扩增谱

Fig.4 Amplified profiles obtained by using GsDREB1 and/or GsINT primers 1: DREB-rage1; 2, 8: DREB-rage1 & Gs-1; 3: Gs-1; 4, 9: GmDR1 & Gs-1; 5: GmDR1; 6, 10: DREB-rage2 & Gs-1; 7: DREB-rage2; M: 250 bp ladder

图5 用探针GsDREB1进行的野大豆各种DREB和整合酶基因引物及两引物间的扩增谱的Southern 杂交 A: 曝光2.5 h Exposed for 2.5 h B: 曝光1 min Exposed for 1 min 1~10样品同图4 1-10 see Fig. 4

Fig.5 Southern blotting of amplified products using GsDREB1 and/or GsINT separated on the agarose gel shown in Fig. 4. Probe: GsDREB1

图6 野大豆盐渍种群植株DREB1保守序列及其5'上游逆转录转座子INT之间序列的扩增长度多样性扩增引物:GmDR1和 Gs-1。黑色箭头指示主要扩增产物分子量, 白色箭头指多态位点。M: 50 bp ladder 分子量标准;M1: 250 bp ladder 分子量标准 Primers: GmDR1 and Gs-1. Black arrows showed molecular weight (base pair) of major amplified products. White arrows indicated polymorphic bands

Fig.6 Amplified length polymorphism between DREB1 and GsINT of individuals in salinity populations of wild soybean (G. soja)

图7 野大豆4-22植株500 bp扩增产物的序列。下画线为两翼的引物Gs-1和GmDR1

Fig.7 Sequence of a 500 bp product amplified from plant 4-22 using primers Gs-1 and GmDR1 (underlined)

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