李俊,李夏瑩,王顥潛,翟杉杉,陳子言,高鴻飛,李允靜,吳剛,張秀杰,武玉花
轉(zhuǎn)基因油菜篩查陽性質(zhì)粒分子的研制及應(yīng)用
李俊1,李夏瑩2,王顥潛2,翟杉杉1,陳子言2,高鴻飛1,李允靜1,吳剛1,張秀杰2,武玉花1
(1中國農(nóng)業(yè)科學(xué)院油料作物研究所/農(nóng)業(yè)部油料作物生物學(xué)與遺傳育種重點(diǎn)實(shí)驗(yàn)室,武漢 430062;2農(nóng)業(yè)農(nóng)村部科技發(fā)展中心,北京 100025)
【】轉(zhuǎn)基因油菜是四大轉(zhuǎn)基因作物之一,是中國轉(zhuǎn)基因生物安全監(jiān)管的重要對象,轉(zhuǎn)基因檢測為轉(zhuǎn)基因安全監(jiān)管提供技術(shù)支撐。轉(zhuǎn)基因篩查是轉(zhuǎn)基因檢測的第一步,篩查靶標(biāo)設(shè)置不合理會導(dǎo)致漏檢部分轉(zhuǎn)基因成分。建立轉(zhuǎn)基因油菜篩查策略,并研制與篩查策略配套的陽性質(zhì)粒分子,將為中國的轉(zhuǎn)基因油菜安全監(jiān)管提供強(qiáng)有力的技術(shù)支撐。通過收集數(shù)據(jù)庫中登記的轉(zhuǎn)基因油菜品種的外源基因元件信息,分析轉(zhuǎn)基因油菜品種中常用的調(diào)控元件和標(biāo)記基因,基于最大篩查覆蓋率原則,確定轉(zhuǎn)基因油菜的篩查靶標(biāo)。通過檢索數(shù)據(jù)庫或查詢專利,收集篩查元件的核苷酸序列。一個(gè)篩查元件通常有多個(gè)標(biāo)準(zhǔn)方法,查閱各篩查元件的檢測標(biāo)準(zhǔn),分析各標(biāo)準(zhǔn)中普通PCR引物對和實(shí)時(shí)熒光PCR引物/探針組合在篩查元件核苷酸序列中的位置,根據(jù)引物探針的結(jié)合位點(diǎn),確定擬構(gòu)建到質(zhì)粒上的各篩查元件的核苷酸序列。人工合成各篩查元件和油菜內(nèi)標(biāo)基因的融合序列,克隆到常用質(zhì)粒pUC18,構(gòu)建陽性質(zhì)粒分子。采用各篩查元件的普通PCR和實(shí)時(shí)熒光PCR方法,評估陽性質(zhì)粒分子的適用性。建立了轉(zhuǎn)基因油菜的篩查策略,通過檢測CaMV 35S啟動(dòng)子、FMV 35S啟動(dòng)子、、、、、、NOS終止子和PinⅡ終止子共9個(gè)基因元件,可實(shí)現(xiàn)已知信息轉(zhuǎn)基因油菜品種的全覆蓋。構(gòu)建出聚合9個(gè)篩查元件和2個(gè)油菜內(nèi)標(biāo)基因和的轉(zhuǎn)基因油菜篩查質(zhì)粒分子pYCSC-1905。9個(gè)篩查元件和2個(gè)油菜內(nèi)標(biāo)基因的擴(kuò)增效率均在90%—110%,證明質(zhì)粒分子上的不同靶標(biāo)序列沒有相互干擾,影響PCR的擴(kuò)增效率。質(zhì)粒分子pYCSC-1905可用作9個(gè)篩查元件和2個(gè)油菜內(nèi)標(biāo)基因的通用陽性對照,適用于國家標(biāo)準(zhǔn)(GB/T和農(nóng)業(yè)農(nóng)村部公告)、出入境檢驗(yàn)檢疫行業(yè)標(biāo)準(zhǔn)(SN/T)和歐盟標(biāo)準(zhǔn)。提出的轉(zhuǎn)基因油菜篩查策略涵蓋9個(gè)基因元件,可實(shí)現(xiàn)從商業(yè)化到安全評價(jià)各階段轉(zhuǎn)基因油菜的篩查檢測,顯著降低轉(zhuǎn)基因油菜的篩查漏檢率。研制的配套質(zhì)粒分子pYCSC-1905為轉(zhuǎn)基因油菜篩查和各基因元件標(biāo)準(zhǔn)方法的應(yīng)用提供了通用標(biāo)準(zhǔn)樣品,保證檢測機(jī)構(gòu)間檢測數(shù)據(jù)的準(zhǔn)確性和可比性。
轉(zhuǎn)基因油菜;篩查;篩查策略;陽性質(zhì)粒分子;應(yīng)用
【研究意義】轉(zhuǎn)基因油菜是四大轉(zhuǎn)基因作物之一,是食用油和飼料餅粕的重要來源,已在加拿大、美國、澳大利亞等國家大規(guī)模商業(yè)化種植。為了滿足食用油和餅粕供應(yīng),中國每年需從國外進(jìn)口油菜籽,2015年進(jìn)口量超過500萬噸,其中90%以上為轉(zhuǎn)基因菜籽。中國也是油菜種植大國,轉(zhuǎn)基因研究活躍,不斷有品種進(jìn)入田間試驗(yàn)階段。轉(zhuǎn)基因油菜是中國轉(zhuǎn)基因生物安全監(jiān)管的重要對象。轉(zhuǎn)基因篩查檢測是轉(zhuǎn)基因生物安全監(jiān)管的第一步,以轉(zhuǎn)基因作物中常用的啟動(dòng)子、終止子和目的基因?yàn)闄z測靶標(biāo),通過篩查樣品中常用基因元件的有無,可初步判定樣品中是否含有轉(zhuǎn)基因成分[1]。在轉(zhuǎn)基因篩查時(shí),如果設(shè)置的篩查靶標(biāo)不能充分覆蓋已有轉(zhuǎn)基因產(chǎn)品,會導(dǎo)致部分轉(zhuǎn)基因產(chǎn)品的漏檢。而且,在進(jìn)行轉(zhuǎn)基因篩查檢測時(shí),常常面臨缺乏標(biāo)準(zhǔn)樣品的難題。因此,研究轉(zhuǎn)基因油菜的篩查檢測策略,并根據(jù)篩查靶標(biāo)研制篩查檢測用陽性質(zhì)粒分子,對中國的轉(zhuǎn)基因油菜安全監(jiān)管具有重大意義?!厩叭搜芯窟M(jìn)展】2004年,中國批準(zhǔn)進(jìn)口轉(zhuǎn)基因油菜籽用作加工原料,為了對轉(zhuǎn)基因油菜進(jìn)行安全監(jiān)管,一直大力推動(dòng)轉(zhuǎn)基因油菜檢測技術(shù)標(biāo)準(zhǔn)體系的建設(shè),現(xiàn)在中國已初步建立起轉(zhuǎn)基因油菜檢測技術(shù)標(biāo)準(zhǔn)體系,包括國家標(biāo)準(zhǔn)(GB/T)[2-3]、農(nóng)業(yè)農(nóng)村部公告[4-8]、出入境檢驗(yàn)檢疫行業(yè)標(biāo)準(zhǔn)[9-12]等。標(biāo)準(zhǔn)方法主要是基于基因組DNA擴(kuò)增的PCR方法,檢測靶標(biāo)包括花椰菜病毒的35S啟動(dòng)子(P-CaMV35S)、胭脂堿合成酶NOS終止子(T-NOS)等調(diào)控元件[4,11],新霉素磷酸轉(zhuǎn)移酶基因()、膦絲菌素乙酰轉(zhuǎn)移酶基因()、膦絲菌素乙酰轉(zhuǎn)移酶基因()等功能基因[5-13],以及批準(zhǔn)進(jìn)口的MS8、RF3、GT73等轉(zhuǎn)化體[11]。雖然針對各個(gè)基因元件都發(fā)布了標(biāo)準(zhǔn)方法,但在轉(zhuǎn)基因油菜篩查檢測時(shí),應(yīng)該檢測哪些靶標(biāo),還沒有明確的規(guī)定。各家轉(zhuǎn)基因檢測實(shí)驗(yàn)室在檢測轉(zhuǎn)基因油菜時(shí),都是自行設(shè)置檢測靶標(biāo),導(dǎo)致實(shí)驗(yàn)室間的檢測結(jié)果缺乏可比性。張麗等[13]曾基于商業(yè)化轉(zhuǎn)基因油菜中基因元件使用頻率的分析,確定了轉(zhuǎn)基因油菜的篩查檢測策略,認(rèn)為檢測P-CaMV35S、玄參花葉病毒35S啟動(dòng)子(P-FMV35S)、、5-烯醇式丙酮酸莽草酸-3-磷酸合酶基因()、和T-NOS共6個(gè)基因元件,可100%檢測出批準(zhǔn)進(jìn)口轉(zhuǎn)基因油菜品種。劉冰[14]研究認(rèn)為檢測P-CaMV35S、T-NOS、、、和6個(gè)靶標(biāo)元件的組合,理論上可篩查92%的已知商業(yè)化轉(zhuǎn)基因油菜轉(zhuǎn)化事件。隨著轉(zhuǎn)基因油菜新品種的推出,采用這兩個(gè)篩查策略均會導(dǎo)致部分轉(zhuǎn)基因油菜品種發(fā)生漏檢。標(biāo)準(zhǔn)物質(zhì)或標(biāo)準(zhǔn)樣品是進(jìn)行轉(zhuǎn)基因檢測的物質(zhì)基礎(chǔ),應(yīng)用標(biāo)準(zhǔn)物質(zhì)可保證檢測結(jié)果的準(zhǔn)確性、可靠性和可比性。基體標(biāo)準(zhǔn)物質(zhì)的研制和生產(chǎn)受原材料供應(yīng)等方面的限制,而質(zhì)粒標(biāo)準(zhǔn)分子的研制則不依賴轉(zhuǎn)基因原材料,因此,質(zhì)粒標(biāo)準(zhǔn)分子成為基體標(biāo)準(zhǔn)物質(zhì)的最佳替代品,適宜在轉(zhuǎn)基因定性檢測中用作陽性標(biāo)準(zhǔn)樣品[15]。迄今為止,中國僅研制出了一個(gè)轉(zhuǎn)基因油菜T45質(zhì)粒標(biāo)準(zhǔn)物質(zhì)(GBW(E)100340),該標(biāo)準(zhǔn)物質(zhì)僅能用于油菜T45轉(zhuǎn)化體的特異識別和定量,不能用于轉(zhuǎn)基因油菜篩查檢測。為了滿足轉(zhuǎn)基因油菜的檢測需求,LI等[16]將RF1、RF2、MS1、MS8、Topas 19/2、Oxy235、RT73和T45共8個(gè)轉(zhuǎn)化體的靶標(biāo)序列融合構(gòu)建到一個(gè)質(zhì)粒分子上,研制出一個(gè)多靶標(biāo)的油菜質(zhì)粒分子,但該質(zhì)粒分子不能用于轉(zhuǎn)基因油菜篩查檢測。Wu等[17]將P-CaMV35S、P-FMV35S、胭脂堿合成酶NOS啟動(dòng)子(P-NOS)、、、潮霉素磷酸轉(zhuǎn)移酶基因()、磷酸甘露糖異構(gòu)酶基因()、T-NOS、花椰菜病毒的35S終止子(T- CaMV35S)、TL-DNA基因7終止子(T-g7)和E9基因3’終止子(T-e9)11個(gè)外源基因元件和玉米、油菜、大豆、棉花、水稻和小麥六大作物內(nèi)標(biāo)基因的靶標(biāo)序列,融合構(gòu)建到一個(gè)質(zhì)粒上,研制出一個(gè)通用的篩查質(zhì)粒分子,但該分子不是針對轉(zhuǎn)基因油菜研制,在應(yīng)用時(shí)會導(dǎo)致個(gè)別轉(zhuǎn)基因油菜品種的漏檢。徐俊鋒等[18]構(gòu)建了油菜篩查質(zhì)粒分子pMD-rape,以作為油菜內(nèi)標(biāo)準(zhǔn)基因,攜帶P-CaMV35S、P-FMV35S、花藥組織特異基因TA29啟動(dòng)子(PTa29)、P-NOS、T-NOS、T-CaMV35S和T-g7 7個(gè)檢測靶標(biāo)序列,覆蓋90%的轉(zhuǎn)基因油菜品種,但該質(zhì)粒分子只適用于通過農(nóng)業(yè)部公告發(fā)布的標(biāo)準(zhǔn),不適用于國家標(biāo)準(zhǔn)(GB/T)和出入境檢驗(yàn)檢疫行業(yè)標(biāo)準(zhǔn)(SN/T)?!颈狙芯壳腥朦c(diǎn)】前期研究雖然曾提出轉(zhuǎn)基因油菜的篩查檢測策略,但存在檢測參數(shù)設(shè)置不合理導(dǎo)致個(gè)別轉(zhuǎn)化體漏檢的問題。相應(yīng)地,構(gòu)建的轉(zhuǎn)基因油菜篩查質(zhì)粒分子也只能覆蓋大部分轉(zhuǎn)基因油菜品種。因此,在轉(zhuǎn)基因油菜安全監(jiān)管工作中,現(xiàn)有轉(zhuǎn)基因油菜篩查策略和篩查用標(biāo)準(zhǔn)樣品均難以滿足現(xiàn)階段檢測需求。【擬解決的關(guān)鍵問題】本研究通過分析商業(yè)化轉(zhuǎn)基因油菜和試驗(yàn)階段轉(zhuǎn)基因油菜的常用基因元件,提出轉(zhuǎn)基因油菜的篩查檢測策略,研制轉(zhuǎn)基因油菜篩查檢測用質(zhì)粒標(biāo)準(zhǔn)分子,為轉(zhuǎn)基因油菜的篩查檢測提供陽性對照。進(jìn)一步完善中國的轉(zhuǎn)基因油菜檢測、監(jiān)測技術(shù)標(biāo)準(zhǔn)體系,有效發(fā)揮標(biāo)準(zhǔn)方法在轉(zhuǎn)基因生物安全監(jiān)管中的作用,提高中國對非授權(quán)轉(zhuǎn)基因油菜產(chǎn)品非法擴(kuò)散的檢測、監(jiān)測水平,為中國的轉(zhuǎn)基因生物安全監(jiān)管提供有效的技術(shù)支撐。
轉(zhuǎn)基因油菜標(biāo)準(zhǔn)物質(zhì)GT73(0304-B2)、RF1(0711-B2)、MS1(0711-A3)、RF2(0711-C2)、MS8(0306-F6)、RF3(0306-G5)、OXY235、T45(0208-A5)、Topas19 /2(0711-D3)、MON88302(1011-A)購自美國油脂化學(xué)家協(xié)會(American Oil Chemists’ Society,AOCS);轉(zhuǎn)基因油菜73496(ERM- BF434b)的標(biāo)準(zhǔn)物質(zhì)購自歐盟的標(biāo)準(zhǔn)物質(zhì)與測量研究所(institute for reference materials and measurements,IRMM)。
用pUC18質(zhì)粒作為標(biāo)準(zhǔn)質(zhì)粒分子的載體骨架。PCR引物和探針由上海生物工程技術(shù)服務(wù)有限公司合成。
確定轉(zhuǎn)基因油菜篩查元件的核苷酸序列后,將各基因元件的核苷酸序列拼接到一起,送到上海生物工程有限公司人工合成核苷酸序列,將合成的核苷酸序列構(gòu)建到pUC18質(zhì)粒分子上。然后對質(zhì)粒分子進(jìn)行重測序,確定核苷酸序列的準(zhǔn)確性。
用Qiagen的基因組DNA提取試劑盒提取標(biāo)準(zhǔn)樣品的基因組DNA。用紫外分光光度計(jì)測定所提取基因組DNA的純度和濃度,要求OD260/OD230>2.0,OD260/OD280為1.8—2.0。
在普通PCR儀C1000 TouchTM(Bio-rad,USA)上進(jìn)行PCR反應(yīng),PCR反應(yīng)體系為25 μL,含20 ng基因組DNA、1×PCR buffer、5 mmol·L-1MgCl2,200 μmol·L-1dNTPs、400 nmol·L-1引物、1單位Taq酶(Takara,Shiga,Japan)。PCR反應(yīng)程序?yàn)?4℃ 2 min;94℃ 20 s,60℃ 30 s,72℃ 30 s,35個(gè)循環(huán);72℃ 2 min。2%瓊脂糖凝膠電泳檢測PCR產(chǎn)物,EB染色后,在凝膠成像儀中觀測結(jié)果(Bio-rad,USA)。
在實(shí)時(shí)熒光PCR儀CFX96TM上進(jìn)行實(shí)時(shí)熒光PCR反應(yīng),PCR反應(yīng)體系為20 μL,含20 ng基因組DNA、1×TaqMan Universal PCR Master Mix(ABI,USA)、400 nmol·L-1引物、200 nmol·L-1探針。反應(yīng)程序?yàn)?0℃預(yù)酶切2 min;95℃ UNG滅活10 min;95℃ 15 s,60℃ 1 min,50個(gè)循環(huán)。用CFX Manager?軟件(Bio-rad,USA)分析數(shù)據(jù)。
查閱國際農(nóng)業(yè)生物技術(shù)應(yīng)用服務(wù)組織(The International Service for the Acquisition of Agri-biotech Applications,ISAAA)的“GMO Approved Database”數(shù)據(jù)庫(http://www.isaaa.org/gmapprovaldatabase/ cropslist/default.asp)和改性活生物體登記(Living Modified Organism (LMO) Registry)數(shù)據(jù)庫(http://bch.cbd.int/database/lmo-registry),分析轉(zhuǎn)基因油菜產(chǎn)業(yè)化和研發(fā)現(xiàn)狀。ISAAA數(shù)據(jù)庫中可查詢到41個(gè)轉(zhuǎn)基因油菜品種,包括14個(gè)復(fù)合性狀品種和27個(gè)獨(dú)立轉(zhuǎn)化體品種,其中,轉(zhuǎn)基因油菜Topas 19/2被統(tǒng)計(jì)2次,分別對應(yīng)HCN10和HCN92(表1)。LMO數(shù)據(jù)庫中登記了55個(gè)轉(zhuǎn)基因油菜品系,有28個(gè)轉(zhuǎn)基因油菜品系未出現(xiàn)在ISAAA數(shù)據(jù)庫中,其中2個(gè)品系含有,6個(gè)品系含有,其余品系未提供功能基因和調(diào)控元件信息。
表1 ISAAA數(shù)據(jù)庫中登記的轉(zhuǎn)基因油菜品種
中國批準(zhǔn)了耐除草劑油菜Ms1×Rf1、Ms1×Rf2、Ms8×Rf3、T45、Topas19/2、Oxy-235、GT73、RF3和MON88302 9個(gè)品種進(jìn)口用作加工原料,涉及10個(gè)獨(dú)立轉(zhuǎn)化體MS1、RF1、RF2、MS8、RF3、T45、OXY235、Topas 19/2、GT73和MON88302。在中國曾做過安全評價(jià),但還未批準(zhǔn)進(jìn)口的有2個(gè)品種,分別是MS8×RF3×GT73和73496,涉及1個(gè)新轉(zhuǎn)化體73496。
確定轉(zhuǎn)基因油菜篩查的基因元件要考慮2個(gè)因素,一個(gè)是基因元件的使用頻率高;另一個(gè)是組合使用不同基因元件可達(dá)到最高的品種覆蓋率,最好對已知品種覆蓋率達(dá)到100%。統(tǒng)計(jì)分析轉(zhuǎn)基因油菜中使用的基因元件,ISAAA數(shù)據(jù)庫中有26個(gè)獨(dú)立轉(zhuǎn)基因油菜轉(zhuǎn)化體,能查閱到完整遺傳轉(zhuǎn)化信息的有19個(gè),包含中國已批準(zhǔn)進(jìn)口的10個(gè)轉(zhuǎn)化體(MS1、RF1、RF2、MS8、RF3、T45、OXY235、Topas 19/2、MON88302和GT73)和可能將批準(zhǔn)進(jìn)口的轉(zhuǎn)化體73496。轉(zhuǎn)基因油菜不育系MS11擬取代MS8,用于商業(yè)化生產(chǎn),但沒有查閱到其完整的遺傳轉(zhuǎn)化信息。ISAAA數(shù)據(jù)庫中提供的信息顯示,MS11含有表達(dá)框、表達(dá)框和表達(dá)框。LMO數(shù)據(jù)庫中另外登記的28個(gè)轉(zhuǎn)化體中有2個(gè)轉(zhuǎn)化體含有,6個(gè)轉(zhuǎn)化體含有,其余轉(zhuǎn)化體未提供明確的外源元件及基因信息。油菜作為四大轉(zhuǎn)基因作物之一,中國轉(zhuǎn)基因研究非常活躍,在1992—2015年間有497篇與轉(zhuǎn)基因油菜相關(guān)的論文發(fā)表[19]。在基因工程研究中,除了用、作為選擇標(biāo)記外,還大量用作為選擇標(biāo)記。
通過分析查閱到的轉(zhuǎn)基因油菜品系中常用的外源元件和標(biāo)記基因的使用頻率,以及常用遺傳轉(zhuǎn)化載體中含有的調(diào)控元件和標(biāo)記基因,確定用9個(gè)基因元件進(jìn)行轉(zhuǎn)基因油菜的篩查檢測,分別是(1)P-CaMV 35S、(2)P-FMV 35S、(3)、(4)、(5)修飾的、(6)、(7)T-NOS、(8)馬鈴薯蛋白酶抑制因子Ⅱ終止子(T-PinⅡ)和(9)。9個(gè)基因元件在20個(gè)已知信息油菜轉(zhuǎn)化體中的分布如表2所示。對這9個(gè)基因元件進(jìn)行檢測,可實(shí)現(xiàn)20個(gè)已知轉(zhuǎn)基因油菜品種、LMO數(shù)據(jù)庫中已知遺傳轉(zhuǎn)化信息品種的全覆蓋,批準(zhǔn)進(jìn)口品種覆蓋2—3次。通過將作為檢測參數(shù),可覆蓋部分實(shí)驗(yàn)室研究階段的材料。
表2 9個(gè)篩查元件在油菜轉(zhuǎn)化體中的分布
9個(gè)篩查元件的完整核苷酸序列信息如表3所示,在轉(zhuǎn)基因檢測中,每個(gè)篩查元件僅有部分核苷酸序列用作檢測靶標(biāo),因此,本研究僅將各元件的檢測靶標(biāo)序列構(gòu)建到質(zhì)粒分子中。在確定9個(gè)篩查元件的靶標(biāo)序列時(shí),要求擬構(gòu)建的質(zhì)粒分子不僅可用作普通PCR檢測的陽性對照,還可用作實(shí)時(shí)熒光PCR檢測的陽性對照;不僅適用于農(nóng)業(yè)部發(fā)布標(biāo)準(zhǔn),還適用于GB/T、SN/T和歐盟標(biāo)準(zhǔn)。
查閱9個(gè)篩查元件的檢測標(biāo)準(zhǔn),包括GB/T檢測標(biāo)準(zhǔn)[2-3]、農(nóng)業(yè)農(nóng)村部發(fā)布的檢測標(biāo)準(zhǔn)(農(nóng)業(yè)農(nóng)村部公告)[4-8]、SN/T檢測標(biāo)準(zhǔn)[9-12]和歐盟標(biāo)準(zhǔn)[20-33],收集各標(biāo)準(zhǔn)中針對這9個(gè)篩查元件的普通PCR方法和實(shí)時(shí)熒光PCR方法(表3)。分析各標(biāo)準(zhǔn)中普通PCR引物對和實(shí)時(shí)熒光PCR引物/探針組合在篩查元件核苷酸序列中的位置,確定擬構(gòu)建到質(zhì)粒上的各篩查元件的靶標(biāo)核苷酸序列。選用和作為轉(zhuǎn)基因油菜內(nèi)標(biāo)基因。各篩查元件的靶標(biāo)序列長度及油菜內(nèi)標(biāo)基因和的核苷酸序列信息如表3所示。
將9個(gè)篩查元件和2個(gè)油菜內(nèi)標(biāo)基因的靶標(biāo)序列拼接到一起,獲得一條長4 433 bp的融合序列(圖1)。將融合序列送到上海生工進(jìn)行全序列人工合成,將人工合成的序列通過RⅤ酶切位點(diǎn)插入pUC18質(zhì)粒分子中,構(gòu)建轉(zhuǎn)基因油菜篩查質(zhì)粒分子pYCSC-1905(圖2)。然后將構(gòu)建的轉(zhuǎn)基因油菜篩查質(zhì)粒分子pYCSC-1905進(jìn)行全分子測序,測得的序列與預(yù)期序列完全一致。
表3 各篩查元件和油菜內(nèi)標(biāo)基因的核苷酸序列、標(biāo)準(zhǔn)方法信息
表中CT-PCR表示普通PCR,RT-PCR表示實(shí)時(shí)熒光PCR
CT-PCR indicates conventional PCR, RT-PCR indicates real-time PCR
圖1 篩查元件和油菜內(nèi)標(biāo)基因融合序列示意圖
圖2 轉(zhuǎn)基因油菜篩查質(zhì)粒分子結(jié)構(gòu)示意圖
將轉(zhuǎn)基因油菜GT73、MS1、RF1、MS1、RF2、MS8、RF3、OXY235、T45、Topas19 /2、MON88302和73496的基因組DNA,作為測試樣品,將質(zhì)粒分子pYCSC-1905設(shè)為陽性對照,進(jìn)行轉(zhuǎn)基因油菜普通PCR和實(shí)時(shí)熒光PCR篩查檢測,引物、探針序列見電子附表1。將普通PCR產(chǎn)物進(jìn)行凝膠電泳分析,各篩查元件和油菜內(nèi)標(biāo)基因在陽性對照和相應(yīng)的轉(zhuǎn)基因油菜樣品中均擴(kuò)增出預(yù)期產(chǎn)物,在不含有相應(yīng)元件的樣品中沒有擴(kuò)增產(chǎn)物(圖4)。實(shí)時(shí)熒光PCR擴(kuò)增結(jié)果表明,各篩查元件和油菜內(nèi)標(biāo)基因在陽性對照和相應(yīng)的轉(zhuǎn)基因油菜樣品中均有典型擴(kuò)增曲線,在不含有相應(yīng)元件的樣品中沒有擴(kuò)增曲線(數(shù)據(jù)未給出)。普通PCR和實(shí)時(shí)熒光PCR的篩查檢測結(jié)果一致,陽性質(zhì)粒分子pYCSC-1905的每個(gè)靶標(biāo)均獲得預(yù)期擴(kuò)增,實(shí)際應(yīng)用結(jié)果進(jìn)一步證實(shí)pYCSC-1905適合用作轉(zhuǎn)基因油菜普通PCR和實(shí)時(shí)熒光PCR篩查檢測的質(zhì)控樣品。
E表示擴(kuò)增效率,2表示標(biāo)準(zhǔn)曲線的決定系數(shù),slope表示標(biāo)準(zhǔn)曲線的斜率,y-int 表示標(biāo)準(zhǔn)曲線的截距
E indicates amplification efficiency,2indicates regression coefficient, slope indicates the slope of standard curve, y-int indicates the intercept of standard curve
圖3 9個(gè)篩查元件和2個(gè)油菜內(nèi)標(biāo)基因的標(biāo)準(zhǔn)曲線繪制和擴(kuò)增效率檢測
Fig. 3 Standard curves and amplification efficiencies of nine screening elements and two rapeseed reference genes
轉(zhuǎn)基因生物安全監(jiān)管一方面要監(jiān)管批準(zhǔn)進(jìn)口的轉(zhuǎn)基因產(chǎn)品是否按規(guī)定流通和使用;另一方面要監(jiān)管中國未批準(zhǔn)進(jìn)口的轉(zhuǎn)基因產(chǎn)品是否非法進(jìn)入市場或田間。其中,對非法轉(zhuǎn)基因產(chǎn)品的檢測和監(jiān)測是轉(zhuǎn)基因生物安全監(jiān)管工作的重中之重。非法(非授權(quán))轉(zhuǎn)基因產(chǎn)品是指未經(jīng)批準(zhǔn)而釋放到市場上的轉(zhuǎn)基因產(chǎn)品,包括在別的國家批準(zhǔn)而在中國并未獲批的轉(zhuǎn)基因材料、田間非法種植的僅批準(zhǔn)進(jìn)口用作加工原料的轉(zhuǎn)基因材料,以及尚處于試驗(yàn)階段的轉(zhuǎn)基因材料。由于轉(zhuǎn)基因產(chǎn)品存在潛在的環(huán)境和食用安全風(fēng)險(xiǎn),一旦發(fā)生非授權(quán)轉(zhuǎn)基因產(chǎn)品的非法擴(kuò)散,將擾亂正常貿(mào)易秩序,在消費(fèi)者中引發(fā)恐慌情緒,對國民經(jīng)濟(jì)、生活產(chǎn)生一系列的惡劣影響。轉(zhuǎn)基因檢測是轉(zhuǎn)基因生物安全監(jiān)管的技術(shù)基礎(chǔ),在轉(zhuǎn)基因檢測中盡量降低漏檢轉(zhuǎn)基因成分的幾率,才能保證轉(zhuǎn)基因生物安全監(jiān)管的有效性。
中國轉(zhuǎn)基因油菜研究活躍,存在很大的非法擴(kuò)散風(fēng)險(xiǎn)。本研究通過分析轉(zhuǎn)基因油菜中基因元件的使用,制定出了組合檢測9個(gè)基因元件(P-CaMV 35S、P-FMV 35S、、、、、、T-NOS、T-PinⅡ)對轉(zhuǎn)基因油菜進(jìn)行篩查檢測的策略,采用本篩查策略可以覆蓋已知信息的轉(zhuǎn)基因油菜品種,并且通過篩查,最大程度覆蓋了試驗(yàn)階段的轉(zhuǎn)基因產(chǎn)品。為了給篩查檢測提供通用的標(biāo)準(zhǔn)樣品,本研究還研制出了轉(zhuǎn)基因油菜篩查質(zhì)粒分子pYCSC-1905,本質(zhì)粒分子可為不同的標(biāo)準(zhǔn)方法提供陽性對照,包括農(nóng)業(yè)部公告、GB/T、SN/T和歐盟標(biāo)準(zhǔn)中涉及的普通定性PCR方法和實(shí)時(shí)熒光PCR方法,具有良好的廣適性。組合使用本研究建立的轉(zhuǎn)基因油菜篩查策略和篩查陽性質(zhì)粒分子pYCSC-1905,不僅可篩查出中國批準(zhǔn)進(jìn)口的轉(zhuǎn)基因油菜,還可篩查出非授權(quán)的轉(zhuǎn)基因油菜品種。
M:marker;1:p-YCSC-1905;2:T45;3:GT73;4:MS8;5:MS1;6:RF1;7:RF2;8:RF3;9:OXY235;10:Topas 19/2;11:73496;12:MON88302;13:陰性對照中油821;14:空白對照
建立了轉(zhuǎn)基因油菜篩查策略,并研制出與轉(zhuǎn)基因油菜篩查策略配套的陽性質(zhì)粒分子pYCSC-1905,為轉(zhuǎn)基因油菜篩查和各基因元件標(biāo)準(zhǔn)方法的使用提供了一個(gè)通用標(biāo)準(zhǔn)樣品。本篩查策略實(shí)現(xiàn)了目前已知信息轉(zhuǎn)基因油菜品種的全覆蓋,降低了轉(zhuǎn)基因油菜篩查檢測中漏檢個(gè)別品種的幾率。
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Development and Application of Plasmid Reference Molecule for Genetically Modified Rapeseed Screening
LI Jun1, LI Xiaying2, WANG Haoqian2, ZHAI Shanshan1, CHEN Ziyan2, GAO Hongfei1, LI Yunjing1, WU Gang1, ZHANG Xiujie2, WU Yuhua1
(1Oil Crops Research Institute, Chinese Academy of Agricultural Sciences/Key Laboratory of Biology and Genetic Improvement of Oil Crop, Ministry of Agriculture, Wuhan 430062;2Development Center of Science and Technology, Ministry of Agriculture and Rural Affairs, Beijing 100025)
【】 Rapeseed is one of the four major genetically modified (GM) crops, the production and application of GM rapeseed must be regulated in China. Performance of GMO detection is the prerequisite to implement GMO regulations, screening is the first step to determine the presence or absence of GMO ingredients in testing samples. Appropriate selection of screening targets can effectively reduce the chance of missed detection of some GM ingredients. A technical platform, involving establishment of screening strategy for GM rapeseed and development of a common reference plasmid that is compatible with the screening strategy, would provide technical support for regulating GM rapeseed.【】 Both regulatory elements and marker genes commonly used in GM rapeseed are obtained by collecting and analyzing the GM rapeseed varieties registered in database, then the screening strategy for GM rapeseed can be determined based on the principle of maximum coverage of GM rapeseed varieties. The whole nucleotide sequences of screening elements are collected by searching nucleotide database or retrieving patent. One screening target usually has multiple standard detection methods, both the primer pairs for conventional PCR and the primers/probe combinations for real-time PCR are aligned with the nucleotide sequence of each screening target to determine the target sequence that would be integrated into plasmid. The fusion sequence of all screening elements together with rapeseed reference genes was artificially synthesized, and cloned into the plasmid pUC18 to construct a positive plasmid molecule. Both conventional PCR and real-time PCR are utilized to evaluate the applicability of constructed plasmid as positive control.【】 The screening strategy for transgenic rapeseed was established by detecting nine elements, involving two promoters of CaMV 35S and FMV 35S, five genes of,,,, and, two terminators of NOS and PinII. This screening strategy achieved full coverage of transgenic rapeseed varieties with known information. The screening plasmid pYCSC-1905 was constructed for GM rapeseed, carrying nine screening elements and 2 rapeseed reference genes ofand. The amplification efficiencies of nine screening elements and two rapeseed reference genes were in the range from 90% to 110%, demonstrating that the amplification efficiency of screening target is not influenced due to the mutual interference of integrated fragments. The plasmid pYCSC-1905 can be used as a common positive control for nine screening targets and two rapeseed reference genes, applicable to national standards (GB/T and Declaration of Ministry of Agriculture and Rural Affairs), Entry-exit inspection and quarantine industry standards (SN/T) and European Union standards.【】The screening strategy covering 9 elements for GM rapeseed screening , can achieve the screening of GM rapeseed in all stages from commercialization to safety assessment, and significantly reduce the missed detection of GM rapeseed. The developed plasmid pYCSC-1905 provides a general positive control for rapeseed screening and the standard methods, and ensures the accuracy and comparability of test results between laboratories.
genetically modified rapeseed; screening; screening strategy; positive plasmid molecule; application
10.3864/j.issn.0578-1752.2020.07.003
2019-08-07;
2019-11-13
轉(zhuǎn)基因生物新品種培育專項(xiàng)(2016ZX08012003)、國家自然科學(xué)基金(31601581)
李俊,E-mail:lijuner126@126.com。通信作者張秀杰,E-mail:zhxj7410@sina.com。通信作者武玉花,E-mail:wuyuhua@oilcrops.cn
(責(zé)任編輯 李莉)