灰飞虱线粒体基因组适应性进化

摘要：灰飞虱[Laodelphax striatellus (Fallén)]属半翅目，飞虱科，是一种非常重要的农业害虫，在世界上分布范围广泛。前期通过线粒体COI和COII基因研究了灰飞虱的种群遗传结构，发现灰飞虱自然种群中存在两种线粒体单倍型HGI和HGII，两者的地理分布与环境温度相关，然而HGI和HGII单倍型间无固定的非同义变异，两者地理分布的遗传机制尚不清楚。为了揭示两者的地理分布规律的遗传机制，本研究通过对HGI和HGII单倍型灰飞虱进行了线粒体全基因组的PCR扩增和测序，分析了两者DNA多样性差异，并通过Tajima’s D的比较了两者选择进化压力。我们分别测得20个HGI和20个HGII线粒体基因组，Wilcoxon signed-rank统计分析表明两单倍型间在同义突变比率和非同义突变比率上均无显著差异（P = 0.08）。Tajima’s D分析结果显示两单倍型的线粒体基因组均受到强烈的负选择，并在HGI单倍型的CYTB基因上发现了一个极显著的正选择信号，且在其附近找到了一个非同义突变，该非同义突变的频率与环境温度呈显著正相关。我们推测这个非同义突变可能有利于灰飞虱在寒冷地区生存。36746
关键词：灰飞虱；线粒体基因；适应性进化
The adaptive evolution of mitochondrial genome in Laodelphax striatellus
Abstract: The small brown planthopper (SBPH), Laodelphax striatellus (Fallén), which belongs to Hemiptera, Delphacidae, is an important agricultural pest and widely distributed in the world. Our previous study found that two mitochondrial haplogroups (HGI & HGII) existed in natural SBPH populations. And the distributions of HGI and HGII were correlated with environmental temperature. However, fixed nonsynonymous mutations were not detected between HGI and HGII in the two genes. The genetic mechanisms underlying the geographical distributions of the two mitochondrial haplogroup was still unclear. To clear this, we amplified and sequenced 20 mitogenomes of HGI and 20 mitogenomes of HGII, repectively, and compared the genetic persity and evolution patterns. Wilcoxon signed-rank test revealed that there is no significant difference between HGI and HGII in synonymous and non-synonymous persity. Tajima’s D test showed both HGI and HGII mitogenomes were under widespread purifying selection, and a positive selection signal was only detected in the HGI mitogenomes on the CYTB gene. Non-synonymous mutation was detected in vicinity of the positive selection signal region. The geographical distribution of the non-synonymous mutation was correlated with the environmental temperature, and riche. We proposed that this non-synonymous mutation on the CTYB gene may be linked to cold adaptation of SBPH.
Key words: small brown planthopper; mitochondrial DNA; adaptive evolution
摘要1
关键词1
Abstract1
Key words1
引言2
1 材料与方法3
1.1 供试虫源3
1.2 DNA提取3
1.3 全线粒体基因组的扩增3
1.4 PCR产物检测，纯化及质量检测学研究中的应用4
1.5 线粒体基因组的测序6
1.6 线粒体基因组拼接分析6
1.7 线粒体基因组选择压分析6
2 结果与分析6
2.1 线粒体基因组DNA多样性6
2.2 线粒体基因组同义突变与非同义突变比较7
2.3 线粒体基因组Tajima’s D8
2.4 CYTB基因非同义突变与气温的关系8
3 讨论9
致谢10
参考文献10
灰飞虱线粒体基因组适应性进化
引言： 1.灰飞虱的重要性及前期种群遗传研究发现的问题
灰飞虱[Laodelphax striatellus(Fallén)]属半翅目，飞虱科，是一种非常重要的农业害虫。广泛分布在古北区与东洋区，主要分布在温带地区，从菲律宾到西伯利亚，再到欧洲，北非等地，国内各地均有分布，以长江流域及北方稻区发生较多。灰飞虱耐寒怕热，最适合的温度是23-25℃，当温度超过30℃时，成虫寿命短，死亡率增加。在南部稻区如广东等地无越冬情况，冬季仍然能够继续危害小麦。其他地区均以3、4龄若虫在麦田、绿肥田等地越冬。刘向东等研究表明在江淮稻区冬季低温环境下对灰飞虱种群的存活影响很小，3龄若虫在0-4℃的低温条件下12小时无冻倒现象，而持续长达20小时冻倒率仅为14.3%，且冻倒者均能在适宜的条件下复苏[1]。灰飞虱主要为害早、中稻秧田和本田分蘖期的稻苗。除以成虫、若虫刺吸为害外，还传播病毒病害。灰飞虱线粒体基因组适应性进化:http://www.youerw.com/shengwu/lunwen_35317.html