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灰飛虱線粒體基因組適應性進化

時間:2019-06-30 07:39來源:畢業論文
在HGI單倍型的CYTB基因上發現了一個極顯著的正選擇信號,且在其附近找到了一個非同義突變,該非同義突變的頻率與環境溫度呈顯著正相關。我們推測這個非同義突變可能有利于灰飛虱

摘要:灰飛虱[Laodelphax striatellus (Fallén)]屬半翅目,飛虱科,是一種非常重要的農業害蟲,在世界上分布范圍廣泛。前期通過線粒體COI和COII基因研究了灰飛虱的種群遺傳結構,發現灰飛虱自然種群中存在兩種線粒體單倍型HGI和HGII,兩者的地理分布與環境溫度相關,然而HGI和HGII單倍型間無固定的非同義變異,兩者地理分布的遺傳機制尚不清楚。為了揭示兩者的地理分布規律的遺傳機制,本研究通過對HGI和HGII單倍型灰飛虱進行了線粒體全基因組的PCR擴增和測序,分析了兩者DNA多樣性差異, 并通過Tajima’s D的比較了兩者選擇進化壓力。我們分別測得20個HGI和20個HGII線粒體基因組,Wilcoxon signed-rank統計分析表明兩單倍型間在同義突變比率和非同義突變比率上均無顯著差異(P = 0.08)。Tajima’s D分析結果顯示兩單倍型的線粒體基因組均受到強烈的負選擇,并在HGI單倍型的CYTB基因上發現了一個極顯著的正選擇信號,且在其附近找到了一個非同義突變,該非同義突變的頻率與環境溫度呈顯著正相關。我們推測這個非同義突變可能有利于灰飛虱在寒冷地區生存。36746
關鍵詞:灰飛虱;線粒體基因;適應性進化
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. 源¥自%六^^維*論-文+網=www.aftnzs.live
Key words: small brown planthopper; mitochondrial DNA; adaptive evolution
摘要1
關鍵詞1
Abstract1
Key words1
引言2
1 材料與方法3
1.1 供試蟲源3
1.2 DNA提取3
1.3 全線粒體基因組的擴增3
1.4 PCR產物檢測,純化及質量檢測學研究中的應用4
1.5 線粒體基因組的測序6
1.6 線粒體基因組拼接分析6
1.7 線粒體基因組選擇壓分析6
2 結果與分析6
2.1 線粒體基因組DNA多樣性6
2.2 線粒體基因組同義突變與非同義突變比較7
2.3 線粒體基因組Tajima’s D8
2.4 CYTB基因非同義突變與氣溫的關系8
3 討論9
致謝10
參考文獻10
灰飛虱線粒體基因組適應性進化
引言:    1.灰飛虱的重要性及前期種群遺傳研究發現的問題
灰飛虱[Laodelphax striatellus(Fallén)]屬半翅目,飛虱科,是一種非常重要的農業害蟲。廣泛分布在古北區與東洋區,主要分布在溫帶地區,從菲律賓到西伯利亞,再到歐洲,北非等地,國內各地均有分布,以長江流域及北方稻區發生較多。灰飛虱耐寒怕熱,最適合的溫度是23-25℃,當溫度超過30℃時,成蟲壽命短,死亡率增加。在南部稻區如廣東等地無越冬情況,冬季仍然能夠繼續危害小麥。其他地區均以3、4齡若蟲在麥田、綠肥田等地越冬。劉向東等研究表明在江淮稻區冬季低溫環境下對灰飛虱種群的存活影響很小,3齡若蟲在0-4℃的低溫條件下12小時無凍倒現象,而持續長達20小時凍倒率僅為14.3%,且凍倒者均能在適宜的條件下復蘇[1]。灰飛虱主要為害早、中稻秧田和本田分蘗期的稻苗。除以成蟲、若蟲刺吸為害外,還傳播病毒病害。 灰飛虱線粒體基因組適應性進化:http://www.aftnzs.live/shengwu/20190630/35317.html
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