趙亞婷,邢紅俠,龐 茜,鄭 旭,張 靖,甕巧云,2,邢繼紅,董金皋
(1.河北省植物生理與分子病理學(xué)重點(diǎn)實(shí)驗(yàn)室,河北農(nóng)業(yè)大學(xué) 真菌毒素與植物分子病理學(xué)實(shí)驗(yàn)室,河北 保定 071001;2.河北北方學(xué)院 農(nóng)林科技學(xué)院,河北 張家口 075000)
灰霉病是一種世界性分布的植物病害,其病原為灰葡萄孢(Botrytiscinerea),主要為害幼果以及成熟的果實(shí)、花序、葉片、果柄等,常導(dǎo)致花序、果實(shí)大量脫落,已成為嚴(yán)重影響我國(guó)大田和溫室作物產(chǎn)量和品質(zhì)的重大病害。目前,灰霉病的防治仍以化學(xué)防治為主,但由于灰葡萄孢具有遺傳變異大、繁殖速度快、適應(yīng)性強(qiáng)以及具有多次再侵染等特點(diǎn),使其對(duì)多種不同作用機(jī)制的殺菌劑產(chǎn)生了抗藥性,導(dǎo)致殺菌劑的使用量逐年增大,并對(duì)農(nóng)產(chǎn)品的安全性造成了嚴(yán)重威脅。因此,挖掘植物抗灰霉病基因,深入研究其抗病分子機(jī)制,為培育抗灰霉病的作物新品種具有重要意義。近年來(lái),從擬南芥中克隆得到的抗病基因以及抗性相關(guān)基因一直是人們研究的熱點(diǎn)。目前,大部分植物抗病基因及抗性相關(guān)基因是從擬南芥中獲得的,如RPS2[1-2]、RPS5、RPS6[3]、RPM1[1,4-5]、RPP4[6-7]、RPP7[8]、RPW8[9-12]等,其中部分抗病基因已經(jīng)應(yīng)用到生產(chǎn)上。研究顯示,植物產(chǎn)生抵抗死體病原菌灰葡萄孢的侵染時(shí),水楊酸(SA)信號(hào)途徑發(fā)揮了重要作用,SA的積累可以增加植物對(duì)灰葡萄孢的局部抗性[13]。通過(guò)高通量轉(zhuǎn)錄組分析,已經(jīng)鑒別了大量植物抵抗灰葡萄孢侵染起作用的轉(zhuǎn)錄因子TFs(Transcription factors)[14-17]。擬南芥T1N6_22基因編碼的蛋白為NAD(P)結(jié)合Rossmann-折疊蛋白家族的成員,具有葡萄糖脫氫酶活性和短鏈氧化還原酶活性,參與植物體內(nèi)各種催化反應(yīng)和新陳代謝過(guò)程,已經(jīng)確定其通過(guò)參與SA和茉莉酸(JA)信號(hào)途徑調(diào)控?cái)M南芥對(duì)灰葡萄孢的抗性[18]。河北農(nóng)業(yè)大學(xué)真菌毒素與植物分子病理學(xué)實(shí)驗(yàn)室前期獲得了一株對(duì)灰葡萄孢敏感的擬南芥突變體,確定了其突變基因?yàn)門1N6_22;通過(guò)互補(bǔ)回復(fù)試驗(yàn),明確了T1N6_22基因在擬南芥抗灰霉病過(guò)程中起正調(diào)控作用,在擬南芥抗丁香假單胞桿菌(PstDC3000)過(guò)程中起負(fù)調(diào)控作用;利用酵母雙雜交技術(shù),以T1N6_22蛋白為誘餌篩選擬南芥的酵母cDNA文庫(kù),獲得了T1N6_22蛋白的候選互作蛋白[19]。但是,T1N6_22蛋白的互作蛋白及其調(diào)控?cái)M南芥抗病的分子機(jī)制尚未明確。
本研究利用酵母雙雜交技術(shù),對(duì)擬南芥抗病相關(guān)基因T1N6_22的互作蛋白進(jìn)行鑒定,旨在為進(jìn)一步明確T1N6_22基因調(diào)控?cái)M南芥抗病的分子機(jī)制奠定基礎(chǔ)。
酵母雙雜交載體PGADT7(AD)和PGBKT7(BD)、酵母菌株AH109、擬南芥Columbia生態(tài)型(Col-0)均由河北省植物生理與分子病理學(xué)重點(diǎn)實(shí)驗(yàn)室、河北農(nóng)業(yè)大學(xué)真菌毒素與植物分子病理學(xué)實(shí)驗(yàn)室提供;酵母轉(zhuǎn)化試劑和酵母培養(yǎng)基購(gòu)于美國(guó)Clontech公司;pCR8克隆試劑盒(K2520-20)和LR克隆試劑盒(11791020)購(gòu)于美國(guó)Invitrogen公司。
提取擬南芥Columbia生態(tài)型(Col-0)植株的總RNA,總RNA提取方法參照提取試劑盒OMEGA Plant RNA Kit的說(shuō)明書。以提取的總RNA為模板,反轉(zhuǎn)錄合成cDNA,cDNA的合成方法參照寶生物反轉(zhuǎn)錄試劑盒的說(shuō)明書。以cDNA為模板,使用T1N6_22基因和AT1G06050、AT1G21400、AT2G19480基因的特異引物進(jìn)行PCR擴(kuò)增(表1)。PCR反應(yīng)體系為MgSO42 μL、10×PCR Buffer 5 μL、dNTP(2.5 mmol/L)1 μL、引物各1 μL、模板cDNA 2 μL、Taq酶0.2 μL,最后加ddH2O至50 μL。PCR程序?yàn)?4 ℃ 2 min;94 ℃ 15 s,56 ℃ 30 s,72 ℃ 1 min,35個(gè)循環(huán)。用1%瓊脂糖凝膠電泳檢測(cè)PCR產(chǎn)物。
表1 引物序列Tab.1 Primer sequence
將T1N6_22基因及其候選互作蛋白基因的PCR擴(kuò)增產(chǎn)物進(jìn)行回收,膠回收方法參照全式金膠回收試劑盒的說(shuō)明書。將回收的基因擴(kuò)增產(chǎn)物分別與Gateway克隆載體pCR8進(jìn)行連接。連接體系為1 μL回收的PCR產(chǎn)物、鹽溶液0.5 μL、ddH2O 1 μL、pCR8 Topo載體0.5 μL,室溫23 ℃反應(yīng)5 min。連接后轉(zhuǎn)化大腸桿菌DH5α,挑取陽(yáng)性克隆進(jìn)行PCR鑒定和測(cè)序驗(yàn)證。
利用質(zhì)粒提取試劑盒,提取經(jīng)測(cè)序正確的pCR8-T1N6_22、pCR8-AT1G06050、pCR8-AT1G21400和pCR8-AT2G19480質(zhì)粒;利用LR重組試劑盒,將4個(gè)基因的入門載體分別與酵母雙雜交載體PGADT7(AD)和PGBKT7(BD)進(jìn)行重組反應(yīng),反應(yīng)體系為質(zhì)粒pCR8-T1N6_22(或者pCR8-AT1G06050、pCR8-AT1G21400、pCR8-AT2G19480)3 μL、AD/BD載體1 μL、LR克隆酶Ⅱ 1 μL,25 ℃連接2 h。2 h后在連接體系中加入蛋白酶K 1 μL,37 ℃ 10 min。將所得到的連接產(chǎn)物轉(zhuǎn)化大腸桿菌DH5α,挑取陽(yáng)性克隆進(jìn)行PCR檢測(cè),將PCR檢測(cè)正確的克隆進(jìn)行進(jìn)一步的測(cè)序鑒定。
將1 μg AD質(zhì)粒分別與1 μg BD-T1N6_22、BD-AT1G06050、BD-AT1G21400和BD-AT2G19480組合共同轉(zhuǎn)化酵母感受態(tài)細(xì)胞AH109,室溫孵育1~2 h,42 ℃熱激30 min后,冰浴1~2 min。將酵母細(xì)胞涂布于二缺(-Leu/-Trp)培養(yǎng)基上,30 ℃培養(yǎng)2~3 d。挑取二缺培養(yǎng)基上生長(zhǎng)良好的酵母單克隆,用100 μL無(wú)菌水稀釋,吸取10 μL點(diǎn)于三缺-Leu/-Trp/-His和添加3-AT的-Leu/-Trp/-His培養(yǎng)基上,30 ℃繼續(xù)培養(yǎng)2~3 d,觀察酵母生長(zhǎng)情況。
將1 μg AD-T1N6_22質(zhì)粒分別與1 μg BD-AT1G06050、BD-AT1G21400和BD-AT2G19480質(zhì)粒組合,將1 μg BD-T1N6_22質(zhì)粒分別與1 μg AD-AT1G06050、AD-AT1G21400和AD-AT2G19480質(zhì)粒組合,同時(shí)設(shè)對(duì)照組合AD-T1N6_22+BD、BD-AT1G06050+AD、BD-AT1G21400+AD、BD-AT2G19480+AD、BD-T1N6_22+AD、AD-AT1G06050+BD、AD-AT1G21400+BD和AD-AT2G19480+BD。將不同組合分別轉(zhuǎn)化酵母感受態(tài)細(xì)胞(200 μL),涂布二缺(-Leu/-Trp)培養(yǎng)基上,30 ℃培養(yǎng)2~3 d。挑取二缺培養(yǎng)基上生長(zhǎng)良好的酵母單克隆,用100 μL無(wú)菌水稀釋,分別吸取10 μL點(diǎn)于二缺-Leu/-Trp、三缺-Leu/-Trp/-His、添加3-AT的三缺-Leu/-Trp/-His 3-AT和四缺-Leu/-Trp/-His/-Ade培養(yǎng)基上,30 ℃繼續(xù)培養(yǎng)2~3 d,觀察酵母生長(zhǎng)情況。
利用T1N6_22基因的特異性引物擴(kuò)增得到T1N6_22基因的全長(zhǎng)(888 bp)(圖1-A),將其與入門載體pCR8連接后轉(zhuǎn)化大腸桿菌DH5α,經(jīng)菌落PCR擴(kuò)增檢測(cè)發(fā)現(xiàn)獲得了單一的目的條帶(圖1-B),進(jìn)一步對(duì)其進(jìn)行測(cè)序驗(yàn)證,獲得T1N6_22基因入門載體pCR8-T1N6_22。將pCR8-T1N6_22與酵母雙雜交載體AD、BD進(jìn)行重組反應(yīng),反應(yīng)產(chǎn)物轉(zhuǎn)化大腸桿菌DH5α,經(jīng)菌落PCR鑒定獲得了單一的目的條帶(圖1-C、D),進(jìn)一步對(duì)重組載體進(jìn)行測(cè)序鑒定,最終獲得T1N6_22基因酵母雙雜交載體AD-T1N6_22和BD-T1N6_22。利用同樣的方法,分別獲得AT1G06050、AT1G21400和AT2G19480基因的酵母雙雜交載體AD-AT1G06050、BD-AT1G06050、AD-AT1G2140、BD-AT1G2140、AD-AT2G19480、BD-AT2G19480(圖2-4)。
A.T1N6_22的PCR擴(kuò)增;B.pCR8-T1N6_22的PCR擴(kuò)增;C.AD-T1N6_22的PCR擴(kuò)增;D.BD-T1N6_22的PCR擴(kuò)增。A.PCR amplification of T1N6_22;B.PCR amplification of pCR8-T1N6_22;C.PCR amplification of AD-T1N6_22;D.PCR amplification of BD-T1N6_22.
A.AT1G06050的PCR擴(kuò)增;B.pCR8-AT1G06050的PCR擴(kuò)增;C.AD-AT1G06050的PCR擴(kuò)增;D.BD-AT1G06050的PCR擴(kuò)增。A.PCR amplification of AT1G06050;B.PCR amplification of pCR8-AT1G06050;C. PCR amplification of the AD-AT1G06050;D. PCR amplification of BD-AT1G06050.
A.AT1G21400的PCR擴(kuò)增;B.pCR8-AT1G21400的PCR擴(kuò)增;C.AD-AT1G21400的PCR擴(kuò)增;D.BD-AT1G21400的PCR擴(kuò)增。A.PCR amplification of AT1G21400;B.PCR amplification of pCR8-AT1G21400;C.PCR amplification of AD-AT1G21400;D.PCR amplification of BD-AT1G21400.
A.AT2G19480的PCR擴(kuò)增;B.pCR8-AT2G19480的PCR擴(kuò)增;C.AD-AT2G19480的PCR擴(kuò)增;D.BD-AT2G19480的PCR擴(kuò)增。A.PCR amplification of AT2G19480;B. PCR amplification of pCR8-AT2G19480;C. PCR amplification of AD-AT2G19480;D. PCR amplification of BD-AT2G19480.
將AD空載體分別與BD-T1N6_22、BD-AT1G06050、BD-AT1G21400和BD-AT2G19480質(zhì)粒組合共轉(zhuǎn)化酵母感受態(tài)細(xì)胞,檢測(cè)各基因的自激活活性。結(jié)果發(fā)現(xiàn),共同轉(zhuǎn)化AD與BD-T1N6_22、BD-AT1G21400和BD-AT2G19480載體的酵母菌落均不能在三缺培養(yǎng)基-Leu/-Trp/-His和-Leu/-Trp/-His 3-AT上生長(zhǎng),共同轉(zhuǎn)化BD-AT1G06050和AD載體的酵母菌落能在三缺(-Leu/-Trp/-His)培養(yǎng)基上正常生長(zhǎng),添加3-AT的三缺培養(yǎng)基-Leu/-Trp/-His 3-AT能夠抑制其生長(zhǎng)(圖5)。表明T1N6_22、AT1G21400、AT2G19480基因無(wú)自激活活性,AT1G06050基因有自激活活性。
圖 5 T1N6_22及其可能互作蛋白自激活活性的鑒定Fig.5 Self-activating activity of T1N6_22 and its candidate interacting protein
將AD-T1N6_22與BD-AT1G06050、BD-T1N6_22與AD-AT1G06050組合進(jìn)行酵母雙雜交試驗(yàn),同時(shí)設(shè)AD-T1N6_22+BD、AD+BD-AT1G06050、BD-T1N6_22+AD、BD+AD-AT1G06050、AD+BD組合作為陰性對(duì)照。結(jié)果發(fā)現(xiàn),共轉(zhuǎn)化AD-T1N6_22與BD-AT1G06050、BD-T1N6_22與AD-AT1G06050組合的酵母菌落在三缺培養(yǎng)基(-Leu/-Trp/-His和-Leu/-Trp/-His 3-AT)和四缺培養(yǎng)基(-Leu/-Trp/-His/-Ade)均能生長(zhǎng),共轉(zhuǎn)化陰性對(duì)照AD與BD-AT1G06050組合的酵母菌落在三缺培養(yǎng)基(-Leu/-Trp/-His)上能夠生長(zhǎng),而共轉(zhuǎn)化其他陰性對(duì)照組合的酵母菌落在三缺培養(yǎng)基(-Leu/-Trp/-His和-Leu/-Trp/-His 3-AT)和四缺培養(yǎng)基(-Leu/-Trp/-His/-Ade)上均不能生長(zhǎng)(圖6)。表明T1N6_22與AT1G06050能在酵母細(xì)胞中直接互作。
利用同樣的方法,檢測(cè)T1N6_22與AT1G21400、AT2G19480之間在酵母中的互作關(guān)系,結(jié)果發(fā)現(xiàn),共轉(zhuǎn)化AD-T1N6_22+BD-AT1G21400、BD-T1N6_22+AD-AT1G21400、AD-T1N6_22+BD-AT2G19480、BD-T1N6_22+AD-AT2G19480組合的酵母菌落在三缺培養(yǎng)基(-Leu/-Trp/-His和-Leu/-Trp/-His 3-AT)和四缺培養(yǎng)基(-Leu/-Trp/-His/-Ade)上均能生長(zhǎng),而陰性對(duì)照組合除BD+AD-AT1G21400和AD+BD在三缺培養(yǎng)基(-Leu/-Trp/-His)上有微弱生長(zhǎng)外,其余陰性對(duì)照組合均不能在三缺和四缺培養(yǎng)基上正常生長(zhǎng)(圖7-8)。表明T1N6_22與AT1G21400、AT2G19480能在酵母細(xì)胞中直接互作。
圖 6 T1N6_22 和AT1G06050酵母雙雜交Fig.6 Results of T1N6_22 and AT1G06050 yeast two-hybrid
圖7 T1N6_22 和AT1G21400酵母雙雜交Fig.7 Results of T1N6_22 and AT1G21400 yeast two-hybrid
圖8 T1N6_22 和AT2G19480酵母雙雜交Fig.8 Results of T1N6_22 and AT2G19480 yeast two-hybrid
酵母雙雜交系統(tǒng)(Yeast two-hybrid system)是分析蛋白與蛋白之間相互作用的有效、快速的方法,可以精確地測(cè)定蛋白質(zhì)之間微弱的相互作用,由于其操作水平是在核酸水平,不需要純化大量的蛋白,因此,操作簡(jiǎn)單容易。但是,酵母雙雜交技術(shù)存在一些自身缺陷,很明顯的一個(gè)缺陷就是存在假陽(yáng)性。因此,酵母雙雜交驗(yàn)證的蛋白質(zhì)相互作用往往還需要其他的試驗(yàn)證據(jù)進(jìn)一步支持。本研究中,利用酵母雙雜交技術(shù)確定了T1N6_22蛋白與AT1G06050、AT1G21400和AT2G19480存在互作關(guān)系?;诮湍鸽p雜交系統(tǒng)自身的局限性,后續(xù)試驗(yàn)中可以采用其他技術(shù)對(duì)其互作關(guān)系進(jìn)行進(jìn)一步的驗(yàn)證。
除了酵母雙雜交之外,還有多種檢測(cè)蛋白互作的方法。如雙分子熒光互補(bǔ)技術(shù)(BiFC)和免疫共沉淀技術(shù)(Co-IP)。其中,BiFC技術(shù)是一個(gè)在活細(xì)胞中檢測(cè)蛋白互作的非常好的工具[20-23];Co-IP技術(shù)是一種在細(xì)胞非變性條件下研究蛋白之間直接互作的方法,可以在體內(nèi)直接確定它們之間相互作用方式的動(dòng)態(tài)變化[24]。
本研究利用酵母雙雜交技術(shù)確定了T1N6_22蛋白的互作蛋白AT1G06050、AT1G21400和AT2G19480,下一步工作可以對(duì)AT1G06050、AT1G21400和AT2G19480的功能進(jìn)行深入研究,明確其在擬南芥抗病中的功能及其與SA和JA信號(hào)途徑之間的關(guān)系,深入探討T1N6_22基因及其互作蛋白基因調(diào)控?cái)M南芥抗病的分子機(jī)制奠定基礎(chǔ)。
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