生物谷：一項針對多種擬南芥的基因研究表明,，環(huán)境因素對物種遺傳多樣性和基因組的影響比之前人們預期的更大。相關(guān)論文發(fā)表在7月20日的《科學》雜志上,。
除了實驗室中科學家的“最愛”，世界各地還分布著多種野生擬南芥,。它們的生長速度、葉子顏色以及發(fā)枝方式都是不同的,。在最新的研究中,，由德國馬普發(fā)育生物學研究所（Max Planck Institute for Developmental Biology）Detlef Weigel領導的國際科學家小組，從美洲,、非洲和亞洲以及其他極地和亞熱帶區(qū)域搜集了19種擬南芥,，并將它們的基因序列（約1.2億個堿基對）與實驗室用擬南芥基因組（2000年測定完成）進行了對比研究，從而確定了相關(guān)的遺傳差異,。
所得到的結(jié)果令人吃驚：它們遺傳差異的廣度遠遠超過了所謂的“改進基因組”（streamlined genome）,。研究人員發(fā)現(xiàn)，平均每180個堿基對中就有一個是可變的,。同時研究表明,，大約4%的實驗室用擬南芥基因組要么與野生種類差異很大，要么完全不存在于野生種類的擬南芥中,。此外,，大約十分之一的野生擬南芥基因是有缺陷的，無法完成正常的功能,。
新的研究結(jié)論為科學家提出了許多新的基礎性問題,。Weigel表示，“或許并不存在所謂的一個物種的基因組,。迄今為止,，對個體DNA序列的認識并不能使科學家充分理解一個物種的遺傳潛能。”此外,，擬南芥基因組的可塑性也令人驚訝,。盡管擬南芥的基因組中的基因數(shù)量與人類和一些作物相當，但它整個基因組的大小不及后兩者的十二分之一,。同時,，擬南芥基因組中幾乎沒有重復序列和無關(guān)聯(lián)的“垃圾”序列。
進一步研究表明,，擬南芥與外界環(huán)境相互作用相關(guān)（比如抵御病原體和感染）的基因,，其可變性大大超過其他功能基因。Weigel認為,，這一遺傳特性反映出擬南芥對當?shù)厣姝h(huán)境的適應性,，正是這些易變基因使得擬南芥能夠經(jīng)受干燥和潮濕,，炎熱和寒冷，并調(diào)節(jié)自身的生長季節(jié),。
新的研究成果加深了人們對環(huán)境影響遺傳多樣性的理解,，也將有助于開發(fā)能夠適應環(huán)境變化的植物品種。隨著人類認識的不斷發(fā)展,，基因與環(huán)境的交互作用已經(jīng)漸漸成為生命科學的重要研究方向,。（科學網(wǎng) 任霄鵬/編譯）
原始出處:
Science 20 July 2007:
Vol. 317. no. 5836, pp. 338 - 342
DOI: 10.1126/science.1138632
Common Sequence Polymorphisms Shaping Genetic Diversity in Arabidopsis thaliana
Richard M. Clark,1 Gabriele Schweikert,1,2,3* Christopher Toomajian,4* Stephan Ossowski,1* Georg Zeller,1,2,5* Paul Shinn,6 Norman Warthmann,1 Tina T. Hu,4 Glenn Fu,7 David A. Hinds,7 Huaming Chen,6 Kelly A. Frazer,7 Daniel H. Huson,5 Bernhard Schölkopf,3 Magnus Nordborg,4 Gunnar Rätsch,2 Joseph R. Ecker,6,8 Detlef Weigel1,8
The genomes of individuals from the same species vary in sequence as a result of different evolutionary processes. To examine the patterns of, and the forces shaping, sequence variation in Arabidopsis thaliana, we performed high-density array resequencing of 20 diverse strains (accessions). More than 1 million nonredundant single-nucleotide polymorphisms (SNPs) were identified at moderate false discovery rates (FDRs), and 4% of the genome was identified as being highly dissimilar or deleted relative to the reference genome sequence. Patterns of polymorphism are highly nonrandom among gene families, with genes mediating interaction with the biotic environment having exceptional polymorphism levels. At the chromosomal scale, regional variation in polymorphism was readily apparent. A scan for recent selective sweeps revealed several candidate regions, including a notable example in which almost all variation was removed in a 500-kilobase window. Analyzing the polymorphisms we describe in larger sets of accessions will enable a detailed understanding of forces shaping population-wide sequence variation in A. thaliana.
1 Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany.
2 Friedrich Miescher Laboratory of the Max Planck Society, 72076 Tübingen, Germany.
3 Department of Empirical Inference, Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany.
4 Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA.
5 Center for Bioinformatics Tübingen, Tübingen University, 72076 Tübingen, Germany.
6 Genomic Analysis Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
7 Perlegen Sciences, 2021 Stierlin Court, Mountain View, CA 94043, USA.
8 Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
* These authors contributed equally to this work.
To whom correspondence should be addressed. E-mail: [email protected]
