發(fā)布時(shí)間：2018-01-21 20:15

  本文關(guān)鍵詞： 突變 同源重組 桃樹 雜合度 世代周期　出處：《南京大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：突變和同源重組是生物體基因組遺傳多樣性的主要來源,也是生物演化過程中不可或缺的重要步驟。目前,科學(xué)家們已經(jīng)對多種生物(酵母,果蠅,小鼠,人,擬南芥、水稻等)的突變或同源重組都進(jìn)行了相關(guān)報(bào)道研究,但系統(tǒng)性的研究主要集中在個(gè)別模式物種,對于多年生木本植物,則僅局限于基因組的某些特定區(qū)段,或者依賴于有限的分子標(biāo)記位點(diǎn),很容易受到遺傳背景差異等各種因素的影響,缺少系統(tǒng)、精確和可靠的評估。另外,很多研究表明,不同物種或者同一物種內(nèi)的不同個(gè)體,其突變率與重組率與其世代周期、參與DNA修復(fù)系統(tǒng)的效率和精度、雜交方式以及基因組的雜合度均存在一定的相關(guān)性。而這些研究結(jié)果在不同物種當(dāng)中的普適性還亟需更多的數(shù)據(jù)來支持和證明。本研究采用二代測序的方法,對多年生木本桃樹的親本-后代群體的一次減數(shù)分裂的突變率和重組率進(jìn)行了全基因組范圍內(nèi)的精確評估,并與一年生模式植物擬南芥進(jìn)行比較,探究影響植物體突變和重組的主要因素。本研究構(gòu)建了3組桃樹種內(nèi)和種間組合,并對每一組F1雜交個(gè)體及其F2自交后代個(gè)體進(jìn)行二代測序。通過生物信息學(xué)分析,從3組共63個(gè)F2自交后代中檢測到240個(gè)點(diǎn)突變和46個(gè)短片段的插入缺失突變。結(jié)果表明,雜合度最高的種間雜交組合Ⅲ的突變率大約是雜合度較低的種內(nèi)雜交組合Ⅰ突變率的1.8倍(BM檢驗(yàn),p=2.22×10-5堿基突變和p=0.0064插入缺失突變)。而不同組之間突變的特征,點(diǎn)突變與插入缺失突變的比例卻并無明顯差異。其次,在一個(gè)世代周期內(nèi),桃樹種內(nèi)雜交組合一次減數(shù)分裂的突變率與一年生植物擬南芥相差無幾。這與桃樹的世代時(shí)長約為擬南芥世代時(shí)長的10～20倍形成鮮明對比,表明單位時(shí)間內(nèi)的桃樹的突變率比擬南芥慢了約1個(gè)數(shù)量級,從而直接驗(yàn)證了世代周期對于物種進(jìn)化速率的貢獻(xiàn)。桃的重組率評估中,種內(nèi)組合Ⅰ的24個(gè)F2樣品中共檢測到286個(gè)交叉互換,相當(dāng)于每次減數(shù)分裂每個(gè)樣本平均11.92次交叉互換或2.64cM/Mbp,與之前研究結(jié)果一致。作為比較,我們利用四分孢子分析,精確評估擬南芥中一次減數(shù)分裂約發(fā)生11.11次交叉互換,重組率約為4.66cM/Mbp�？梢钥闯�,桃中每次減數(shù)分裂每個(gè)樣本的交叉互換率低于一年生雙子葉植物擬南芥(4.0cM/Mbp),同時(shí)也低于一年生單子葉植物水稻(4.53cM/Mbp)。該結(jié)果驗(yàn)證了桃樹與其他多年生木本植物(如蘋果、梨、葡萄、橡木和胡桃木,0.63～2.5cM/Mbp)相對于一年生植物(如擬南芥和水稻)的低重組率。除此之外,桃樹的重組率缺乏與突變明顯的相關(guān)性,可能與栽培桃受到的馴化及強(qiáng)烈的人工選擇有關(guān)。最后,與一年生植物類似,桃樹存在明顯的重組冷點(diǎn)和重組熱點(diǎn),且重組熱點(diǎn)發(fā)生區(qū)域的規(guī)律與非PRDM9物種一致。本研究的創(chuàng)新之處在于,第一次用全基因組測序的方式直接評估了多年生木本桃樹一次減數(shù)分裂的突變率與重組率,填補(bǔ)了全基因組范圍內(nèi)多年生木本植物突變率與重組率精確評估的空白。通過與擬南芥的突變率與重組率進(jìn)行比較,系統(tǒng)性檢驗(yàn)了突變、重組與世代周期長短的關(guān)系,并進(jìn)一步驗(yàn)證了雜交方式或者雜合度對突變率的影響,為物種演化研究提供了新的材料,也為突變與重組機(jī)制的深入發(fā)掘奠定了基礎(chǔ)。
[Abstract]:Mutation and homologous recombination is a major source of genetic diversity of organisms, is an important step in the process of biological evolution. At present, scientists have to many organisms (yeast, Drosophila, mouse, human, Arabidopsis, rice) mutation or homologous recombination have been reported, but the systematic research mainly in the mode of individual species, the perennial woody plant, certain section is limited to the genome, or rely on molecular markers in limited, easily affected by differences in the genetic background of various factors of the lack of systematic, accurate and reliable evaluation. In addition, many studies have shown that different individuals of different species or within the same species, the mutation rate and recombination rate and generation time, efficiency and accuracy in DNA repair system, hybridization and gene heterozygosity there were certain groups Correlation. These results in different species of universality also need more data to support and verify. This research adopts the two generation sequencing, the perennial woody peach parent offspring group of a meiotic division rate of mutation and recombination rates were all based on accurate assessment within the group the annual, and compared with the model plant Arabidopsis thaliana, explore the main factors influencing plant somatic mutation and recombination. This study established 3 groups of peach tree intraspecific and interspecific combinations, and the two generation sequencing of each group of F1 hybrids and F2 inbred offspring. Through bioinformatics analysis, detection from 3 groups a total of 63 F2 progenies to 240 point mutations and 46 short fragments of insertion and deletion. The results showed that the highest heterozygosity of interspecific hybrids of the mutation rate is about intraspecific crosses of sudden low heterozygosity 1.8 times the rate of change (BM test, p=2.22 * 10-5 mutation and p=0.0064 mutation and insertion mutation). Between different groups, point mutation and insertion mutation ratio has no obvious difference. Secondly, in a generation period, peach intraspecific crosses a meiotic mutation rate and the annual plant Arabidopsis thaliana. The peach and not much difference between generation time is approximately the length of the 10 generations of Arabidopsis thaliana to 20 times in stark contrast to that mutation in unit time and rate of peach thaliana slow about 1 orders of magnitude, which directly verify the contribution period for the evolution of species generation rate. The assessment rate of peach the reorganization, I combined within 24 F2 samples were detected in 286 crossover, each equivalent to an average of 11.92 times for each sample of meiotic crossover or 2.64cM/Mbp, consistent with previous reports. As a comparison, we Analysis of four spores using a precise evaluation of Arabidopsis meiosis about 11.11 crossover, recombination rate of about 4.66cM/Mbp. can be seen in each peach meiosis of each sample crossover rate is lower than the annual dicotyledonous plant Arabidopsis thaliana (4.0cM/Mbp), and also lower than the annual monocotyledon rice (4.53cM/Mbp) the results. Verify the peach trees and other woody perennial plants (such as apples, pears, grapes, oak and walnut, 0.63 ~ 2.5cM/Mbp) relative to the annual plant (such as Arabidopsis and rice) the low recombination rate. In addition, the rate of recombination and mutation of peach lacks obvious relevance, domestication and artificial selection may strongly concerned with peach. Finally, similar to the annual peach exist obvious and cold recombination recombination hotspots, and recombination hotspots law consistent with regional non PRDM9 this species. Study on the innovation, for the first time, whole genome sequencing methods to directly evaluate the peach a perennial woody meiotic recombination rate and mutation rate, fill the perennial woody plant genome wide mutation rate blank with recombination rate. Through the comparison of the precise assessment of the rate of mutation and Arabidopsis with recombination rate, system to test the mutation, recombination and generation cycle length, and further verify the hybrid or heterozygosity on influence of mutation rate, provide new material for the evolution of species, but also lay a foundation for the further development and mechanism of recombinant mutant.

【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：S662.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 張志軍;許偉;;生物芯片檢驗(yàn)技術(shù)在醫(yī)學(xué)診斷中的應(yīng)用[J];中國醫(yī)療器械雜志;2013年05期

2 ;Next-generation sequencing technology:A technology review and future perspective[J];Science China(Life Sciences);2010年01期

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本文編號(hào)：1452462