摘" " 要:【目的】探究DdSOC1基因調(diào)控德陽柿(Diospyros deyangensis)成花的分子機(jī)制。【方法】通過生物信息學(xué)、基因表達(dá)量分析、酵母雙雜篩庫和雙雜互作驗(yàn)證等方法,解析DdSOC1基因在調(diào)控成花中的功能。【結(jié)果】德陽柿DdSOC1序列和君遷子DlSOC1序列遺傳距離較近;在成花誘導(dǎo)過程中,DdSOC1在莖、葉、芽中隨開花進(jìn)程出現(xiàn)差異表達(dá);基于柿酵母文庫,篩選獲得7個(gè)DdSOC1的互作蛋白(MIOX、AGL14、JOINTLESS、GL2、NOVEIN、NBS、UBC7),酵母雙雜交和雙分子熒光互補(bǔ)試驗(yàn)表明,DdSOC1和上述7個(gè)蛋白均互作;qRT-PCR結(jié)果顯示,一年生已開花的德陽柿SOC1、AGL14、JOINTLESS、NOVEIN、GL2、UBC7、NBS的表達(dá)量,幼葉高于成齡葉;二年生實(shí)生苗中,SOC1表達(dá)量差異不大,而AGL14、JOINTLESS、GL2、UBC7、MIOX表達(dá)量在開花實(shí)生苗中的表達(dá)量高于未開花實(shí)生苗?!窘Y(jié)論】DdSOC1及其互作蛋白在德陽柿成花轉(zhuǎn)變中發(fā)揮著重要作用,為探究德陽柿短童期分子調(diào)控網(wǎng)絡(luò)提供了更多理論依據(jù)。
關(guān)鍵詞:德陽柿;DdSOC1;互作蛋白;酵母雙雜交;雙分子熒光互補(bǔ);實(shí)時(shí)熒光定量分析
中圖分類號(hào):S665.2 文獻(xiàn)標(biāo)志碼:A 文章編號(hào):1009-9980(2025)02-0276-12
Molecular mechanism of DdSOC1 gene regulating flower bud initiation in Diospyros deyangensis
WAN Jianqi1, DING Yu1, REN Han1, LI Wenxia1, YANG Yong1, HUANG Jinmeng2, GUAN Changfei1*
(1College of Horticulture, Northwest A amp; F University, Yangling 712100, Shaanxi, China; 2Guangxi Academy of Specialty Crops, Guilin 541004, Guangxi, China)
Abstract: 【Objective】 Seedlings of the new identified persimmon species Diospyros deyangensis have a short juvenile stage and can flower within one year after seed sowing. The function of the DdSOC1 gene in controlling flower bud initiation in D. deyangensis was investigated, along with its sequence characterization and expression pattern. 【Methods】 Plant materials were obtained from Nicotiana tabacum and 1- and 2-year-old persimmon (D. deyangensis) seedlings cultivated in the orchard at Northwest A amp; F University under natural conditions. Online analysis of the open reading frame of DdSOC1 was done using the ORF Finder. The physicochemical property of the encoded protein was predicted using Expasy ProtParam program. The MEGA7.0 software was used to create the phylogenetic tree. QRT-PCR was used to examine the expression features of DdSOC1. On the one-deficient and three-deficient plates, the self-toxicity and self-activation of DdSOC1 were explored. Verification of the screening library and yeast interaction was done on a four-lack plate. Confocal microscopy was used in the BiFC experiment. 【Results】 The findings demonstrated that D. deyangnsis SOC1 shared a close genetic distance with SOC1 from Diospyros lotus, Actinidia chinensis, Actinidia eriantha, Camellia sinensis and other species. Populus alba, Vitis vinifera, Malus domestica, Prunus persica, Mangifera indica and other species were distantly linked to D. deyangnsis SOC1 protein. Furthermore, D. deyangnsis SOC1 protein was the most distantly related to that of the herbaceous plants Triticum aestivum and Oryza sativa. Online analysis demonstrated that DdSOC1 protein encodes 126 amino acids. The molecular weight is 14.56 ku. Its isoelectric point is 5.62. SOC1 expression was the highest during flowering and lowest during the bud stage in annual flowering D. deyangnsis stems. As the flowering process progressed, SOC1 expression in the leaves rose. SOC1 expression in the buds peaked during the seedling stage and decreased during the flowering stage. For Y2H, the first deficient plate had plaques, whereas the third plate had none. It demonstrated that DdSOC1 did not have autotoxicity and autoactivation. Following that, DdSOC1 was employed as the bait protein to test the cDNA library of Fuping persimmon. Following colony PCR, the blue plaque on the four-deficient plate in the sieve library was forwarded for sequencing. By comparing the sequences obtained from the screening library with the NCBI BLAST and the genome annotation of D. deyangnsis, seven putative interacting proteins (MIOX, AGL14, JOINTLESS, GL2, NOVEIN, NBS and UBC7) were screened out. The AD vectors of JOINTLESS, NOVEIN, GL2 and other interacting proteins were introduced into BD-SOC1 yeast-competent cells to verify yeast two-hybrid interactions. PGBKT7-53 + pGADT7-T, pGBKT7-Lam + pGADT7-T, and BD-SOC1 + pGADT7 were used as positive, negative and blank control. The combined plasmid was effectively transferred into yeast strains. The findings demonstrated that nine sets of yeast combinations were able to establish white colonies on DDO plates. Plaque was absent from both negative and blank controls on QDO and QDO/X/A plates. On QDO/X/A plates, the positive control and seven yeast combinations (BD-SOC1+AD-NBS, BD-SOC1+AD-JOINTLESS, BD-SOC1+AD-UBC7, BD-SOC1+AD-MIOX, BD-SOC1+AD-GL2, BD-SOC1+AD-NOVEIN and BD-SOC1+AD-AGL14) could grow properly and turn blue. The SOC1 protein and interaction proteins MIOX, JOINTLESS, AGL14, NOVEIN, UBC7 and GL2 in D. deyangensis were evaluated based on the results of the yeast two-hybrid. The pSPYCE (CE) vector of putative interacting proteins and the pSPYNE (NE) vector of DdSOC1 were constructed. Following co-injection, YFP fluorescence signals were seen in tobacco cells. The findings demonstrated that JOINTLESS-cYFP + SOC1-nYFP produced the strongest yellow fluorescence in the tobacco cell membrane and nucleus out of the seven combinations. Other combinations (NOVEIN-cYFP + SOC1-nYFP, UBC7-cYFP + SOC1-nYFP, NBS-cYFP + SOC1-nYFP, GL2-cYFP + SOC1-nYFP and MIOX-cYFP + SOC1-nYFP) detected yellow fluorescence on the cell membrane, while the combination of AGL14-cYFP+SOC1-nYFP produced yellow fluorescence in the nucleus. According to the aforementioned findings, DdSOC1 interacted with seven potential plant interacting proteins. D. deyangensis seedlings with various characteristics (flowering and non-flowering) were examined for the expression of DdSOC1 and its interaction proteins in young leaves (leaves close to the apical bud) and mature leaves (adult leaves distant from the apical bud). According to the findings, juvenile leaves had higher expression levels of SOC1, AGL14, JOINTLESS, NOVEIN, GL2, UBC7 and NBS than mature leaves, but younger leaves had lower expression levels of MIOX. The expression levels of SOC1, NOVEIN and MIOX in young leaves were lower than those in mature leaves in the two-year-old D. deyangensis seedlings, whereas the other genes (GL2, UBC7, NBS, AGL14 and JOINTLESS) exhibited a contrast pattern. 【Conclusion】 This study isolated and cloned the DdSOC1 gene, which was relatively conserved in the evolution of woody plants; DdSOC1 integrated flowering signals from leaves to achieve the transition from vegetative growth to reproductive growth; the results from Y2H and BiFC confirmed that DdSOC1 interacted with interaction protein (MIOX, AGL14, JOINTLESS, GL2, NOVEIN, NBS and UBC7); MIOX may play a role in delaying flowering, while AGL14, JOINTLESS, GL2 and NBS may have a positive influence on the short-childhood of D. deyangensis.
Key words: Diospyros deyangensis; DdSOC1; Interaction protein; Y2H; BiFC; qPCR
德陽柿(Diospyros deyangensis)原產(chǎn)于四川省德陽市,是柿科(Ebenaceae)柿屬(Diospyros)多年生木本植物,屬于雌雄異株落葉果樹樹種,又稱紅花野毛柿。前人通過形態(tài)學(xué)觀察、分子標(biāo)記、染色體倍性分析等手段發(fā)現(xiàn)德陽柿為四倍體,屬于柿屬植物新種[1-2]。木本果樹植物的生命周期分為童期、成年期和衰老期,其中,童期指從種子萌發(fā)至具備正常開花能力的時(shí)期。木本植物的童期普遍較長,一般為3~8 a(年)[3],云杉甚至需要20~25 a才能進(jìn)入成年期[4]。然而,德陽柿作為栽培柿(Diospyros kaki)的近緣種,在播種數(shù)月后即可開花[5],是研究柿屬植物短童期花發(fā)育機(jī)制的優(yōu)良試材。研究短童期調(diào)控的分子機(jī)制對(duì)促進(jìn)柿早花結(jié)實(shí)、提高育種效率具有重要的理論意義和實(shí)踐價(jià)值。
通過對(duì)模式植物擬南芥的研究,發(fā)現(xiàn)了調(diào)控植物開花的重要整合因子SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1)[6]。SOC1隸屬于MADS-box基因家族,它可以整合來自光周期、春化作用、自主途徑等多個(gè)開花調(diào)控途徑的信號(hào),隨后將信號(hào)傳遞給下游的花分生組織基因進(jìn)而促進(jìn)植物成花轉(zhuǎn)化[6-7]。目前已從多種植物,如甜橙(Citrus sinensis)、銀白楊(Populus trichocarpa)、蘋果(Malus domestica)、歐洲葡萄(Vitis vinifera)中克隆出SOC1同源基因[8-11]。SOC1調(diào)控開花的機(jī)制也被廣泛研究[12]。前人研究發(fā)現(xiàn),B3結(jié)構(gòu)域轉(zhuǎn)錄因子REM16通過結(jié)合SOC1和FT(FLOWERING LOCUS T)的啟動(dòng)子促進(jìn)擬南芥開花[13];BjuWRKY71-1通過調(diào)節(jié)SOC1的表達(dá)促進(jìn)芥菜開花[14];應(yīng)激誘導(dǎo)型啟動(dòng)子rd29A通過促進(jìn)AtSOC1的過表達(dá)可以將干旱脅迫下菊花的開花時(shí)間提前[15]。以上研究表明SOC1作為轉(zhuǎn)錄因子受到其他蛋白或核酸的調(diào)控后調(diào)節(jié)植物的開花時(shí)間。此外,SOC1也可以與其他蛋白質(zhì)形成二聚體或高階復(fù)合物靶向調(diào)控開花基因進(jìn)而影響植物開花節(jié)奏[16]。SOC1和AGL6亞家族同源物DAL1相互作用介導(dǎo)松樹營養(yǎng)生長到生殖生長的轉(zhuǎn)變[4];TaSOC1通過與MADS-box開花調(diào)節(jié)因子TaVRT2競(jìng)爭(zhēng)結(jié)合TaVRN1,形成TaSOC1-TaVRN1模塊,整合光周期和春化信號(hào),調(diào)控小麥開花[17];BrSOC1b通過與BrAGL9a、BrAGL9b、BrAGL2和BrAGL8蛋白相互作用,共同參與調(diào)節(jié)白菜的開花[18];擬南芥中SOC1與AGL16形成蛋白質(zhì)復(fù)合物,共同作用于開花靶標(biāo)基因[19]。SOC1在調(diào)控植物開花時(shí)間的過程中起到關(guān)鍵的作用,然而至今還未有德陽柿SOC1基因相關(guān)的報(bào)道,SOC1基因在德陽柿短童期中的作用也尚不清楚。
筆者在本研究中基于前期獲得的德陽柿基因組數(shù)據(jù),分離DdSOC1基因并分析其序列特征,探究DdSOC1基因在不同組織器官中的表達(dá)模式;通過酵母雙雜交(Y2H)篩庫得到DdSOC1的互作蛋白并進(jìn)行了Y2H、雙分子熒光互補(bǔ)(BiFC)的互作驗(yàn)證;分析1年生、2年生德陽柿實(shí)生苗蕾期葉片中互作蛋白基因的表達(dá)量,以期探究DdSOC1基因在德陽柿短童期中的功能,為研究德陽柿短童期分子調(diào)控網(wǎng)絡(luò)提供理論依據(jù)。
1 材料和方法
1.1 試驗(yàn)材料
植物材料為種植于陜西楊凌西北農(nóng)林科技大學(xué)國家柿種質(zhì)資源圃(34°17′42.80″ N,108°04′8.21″ E)的1年生、2年生德陽柿(D. deyangensis)實(shí)生苗;本氏煙(Nicotiana tabacum)。用于實(shí)時(shí)熒光定量的試驗(yàn)材料取自1年生、2年生德陽柿蕾期實(shí)生苗葉片。
菌株:富平尖柿的酵母雙雜交文庫,Y2H Gold酵母菌株以及轉(zhuǎn)入pGBKT7空載、陽性對(duì)照(pGBKT7-53+pGADT7-T)、陰性對(duì)照(pGBKT7-Lam+pGADT7-T)的酵母菌株。
載體:Y2H載體pGBKT7(BD)、pGADT7(AD);BiFC載體pSPYNE(NE)、pSPYCE(CE)。
1.2 DdSOC1基因的克隆和序列分析
使用天根生化科技有限公司多糖多酚試劑盒(DP441)提取德陽柿葉片RNA,使用艾科瑞生物工程有限公司Evo M-MLV反轉(zhuǎn)錄試劑盒(AG11728)將所提RNA反轉(zhuǎn)錄合成模板cDNA。根據(jù)基因組數(shù)據(jù)查詢基因的序列,利用SnapGene Viewer 2.4.3軟件進(jìn)行引物設(shè)計(jì)(表1)。采用艾科瑞高保真試劑盒(AG12202)擴(kuò)增CDS序列。DNA片段連接到pMD19-T載體后轉(zhuǎn)化至大腸桿菌DH5α中,經(jīng)過菌落PCR和測(cè)序,最終得到陽性克隆。
使用ORF Finder(https://www.ncbi.nlm.nih.gov/orffinder/)在線分析開放閱讀框,使用Expasy中的ProtParam(https://www.expasy.org/)工具預(yù)測(cè)編碼蛋白的等電點(diǎn)和分子質(zhì)量,在NCBI上進(jìn)行SOC1-like蛋白搜索,下載相似性較高的蛋白質(zhì)序列,利用MEGA 7.0軟件,選擇鄰接法將相關(guān)物種的SOC1序列構(gòu)建系統(tǒng)進(jìn)化樹(bootstrap設(shè)為1000次)。
1.3 DdSOC1基因的表達(dá)特征
采用qRT-PCR分析DdSOC1基因的表達(dá)特征,引物見表1。將cDNA質(zhì)量濃度稀釋至200 ng·μL-1后作為模板,用SYBR Green Pro Taq HS預(yù)混型qPCR試劑盒(含Rox)(AG11718)進(jìn)行定量實(shí)驗(yàn)。
取一年生開花德陽柿實(shí)生苗莖、葉、芽三個(gè)部位,在苗期、蕾期以及花期測(cè)定DdSOC1表達(dá)水平。
1.4 DdSOC1自毒自激活驗(yàn)證及互作蛋白篩選
1.4.1 DdSOC1自激活驗(yàn)證 以DdSOC1的連T載體質(zhì)粒為模板,設(shè)計(jì)pGBKT7(簡(jiǎn)稱BD)引物(表1)并擴(kuò)增,用SmaⅠ和BamHⅠ對(duì)BD進(jìn)行雙酶切,同源重組后,通過菌液PCR和測(cè)序比對(duì)獲得重組載體pGBKT7-DdSOC1(BD-SOC1)。依照酵母感受態(tài)制備及轉(zhuǎn)化試劑盒(PT1183,源葉生物),獲得BD-SOC1陽性酵母菌株。
在SD/-Trp培養(yǎng)基上分別點(diǎn)BD-SOC1和BD空載的酵母菌液,28 ℃倒置培養(yǎng)2~3 d后觀察酵母生長情況,若BD-SOC1在SD/-Trp平板上正常生長則表明其對(duì)酵母菌株無毒性。
在SD/-Trp/-Ade/-His+X-α-Gal(TDO/X)上分別點(diǎn)上陽性對(duì)照(pGBKT7-53+pGADT7-T)、陰性對(duì)照(pGBKT7-Lam+pGADT7-T)、pGBKT7空載(BD-empty)、BD-SOC1,觀察酵母的生長情況。若BD-SOC1的菌液在三缺板上不長斑則說明不存在自激活,可直接進(jìn)行后續(xù)的篩庫試驗(yàn),若在三缺板上長斑并變藍(lán),則需篩選合適的抑制劑濃度抑制其自激活。
1.4.2 DdSOC1酵母文庫篩選 將柿的核次級(jí)文庫質(zhì)粒轉(zhuǎn)入BD-SOC1的酵母感受態(tài)細(xì)胞中,經(jīng)過轉(zhuǎn)化后,將菌液涂布至SD/-Trp/-Leu/-Ade/-His(QDO)培養(yǎng)基上,觀察單菌落生長情況。挑取單菌落,稀釋后點(diǎn)至SD/-Trp/-Leu/-Ade/-His/X-α-Gal/AbA(QDO/X/A)上,觀察是否有變藍(lán)的菌落。
菌落PCR及測(cè)序:將藍(lán)色單菌落挑至離心管中加入20 μL裂解液(Lysis Buffer for Microorganism to Direct PCR,9164,寶日醫(yī)),熱變性后低速離心,取上清液作為模板進(jìn)行菌落PCR。選擇電泳條帶大于500 bp且單一的菌落PCR產(chǎn)物送至上海生工生物工程有限公司測(cè)序(表2)。
1.4.3 互作蛋白克隆 將篩庫測(cè)序得到的序列在NCBI的BLAST數(shù)據(jù)庫中進(jìn)行比對(duì),根據(jù)功能注釋篩選互作蛋白,在德陽柿基因組中找出對(duì)應(yīng)的CDS序列,并設(shè)計(jì)擴(kuò)增引物(表3)。
1.5 酵母雙雜交(Y2H)
設(shè)計(jì)互作蛋白pGADT7(AD)的引物(表4)并擴(kuò)增,用SmaⅠ和BamHⅠ對(duì)AD載體進(jìn)行雙酶切,同源重組后,對(duì)菌落PCR、提質(zhì)粒及測(cè)序。
參照1.4.2方法,將空載(AD-empty)質(zhì)粒及互作蛋白的AD質(zhì)粒分別轉(zhuǎn)入BD-SOC1酵母感受態(tài)細(xì)胞,處理后的菌液涂布至DDO(SD/-Trp/-Leu)平板上。培養(yǎng)至長出單菌落后,挑取單菌落點(diǎn)至DDO、QDO/X/A板上,觀察酵母生長及變色情況。設(shè)置陽性和陰性對(duì)照。
1.6 雙分子熒光互補(bǔ)(BiFC)
設(shè)計(jì)DdSOC1的pSPYNE(NE)以及互作蛋白pSPYCE(CE)的引物(表1,表5)并擴(kuò)增,同源重組后測(cè)序檢測(cè),并提取重組質(zhì)粒備用。
參照農(nóng)桿菌感受態(tài)說明書將重組質(zhì)粒轉(zhuǎn)化至農(nóng)桿菌感受態(tài)GV3101中,利用菌落PCR鑒定陽性菌株,在雙抗LB液體培養(yǎng)基中培養(yǎng)。離心后棄上清液,用MES溶液重懸菌液,OD600值調(diào)整至0.8后加入乙酰丁香酮,室溫黑暗靜置。將CE和NE侵染液等比例混合,將農(nóng)桿菌侵染液注射進(jìn)煙草葉背,暗培養(yǎng)48 h。使用激光共聚焦顯微鏡(TCS SP8 SR,Leica,德國)觀察YFP熒光。
1.7 互作基因表達(dá)分析
參照1.3的方法,設(shè)計(jì)互作蛋白的定量引物(表6),取蕾期1年生、2年生德陽柿(D. deyangensis)實(shí)生苗頂芽附近3~4枚葉(幼葉)及枝條基部的成年葉分析互作基因表達(dá)量。
1.8 數(shù)據(jù)統(tǒng)計(jì)和分析
所有處理均包括3次重復(fù),數(shù)據(jù)均表示為平均值±標(biāo)準(zhǔn)誤差,統(tǒng)計(jì)分析和作圖使用GraphPad Prism 8軟件完成。
2 結(jié)果與分析
2.1 DdSOC1基因的克隆和序列分析
以德陽柿葉的cDNA為模板擴(kuò)增得到DdSOC1基因,經(jīng)測(cè)序驗(yàn)證擴(kuò)增得到的序列與德陽柿基因組序列一致。該基因CDS全長381 bp,編碼126個(gè)氨基酸;蛋白質(zhì)的分子質(zhì)量為14.56 ku、等電點(diǎn)為5.62。
利用MEGA 7.0軟件對(duì)德陽柿及其他物種的SOC1序列進(jìn)行系統(tǒng)發(fā)育樹分析,結(jié)果(圖1)顯示,DdSOC1和DlSOC1關(guān)系最近,形成一個(gè)小的分支,與中華獼猴桃、毛花獼猴桃、茶SOC1蛋白序列一致性較高;與銀白楊、歐洲葡萄、蘋果、桃、杧果等SOC1蛋白的親緣關(guān)系較遠(yuǎn);與水稻、小麥SOC1蛋白親緣關(guān)系最遠(yuǎn)。
2.2 DdSOC1基因的表達(dá)特征
1年生開花德陽柿不同器官(莖、葉、芽)在不同時(shí)期SOC1的定量結(jié)果(圖2)顯示,莖中SOC1表達(dá)量在蕾期最低,而在花期達(dá)到最高;葉中SOC1表達(dá)量隨著開花進(jìn)程逐漸升高;芽中SOC1的表達(dá)量在幼苗期最高,而在花期最低。
2.3 DdSOC1自毒自激活驗(yàn)證及酵母文庫篩選
分別在SD/-Trp和SD/-Trp/Ade/His + X-α-gal培養(yǎng)基上對(duì)DdSOC1毒性及自激活進(jìn)行檢測(cè),結(jié)果如圖3所示,在SD/-Trp培養(yǎng)基上,BD-SOC1長出菌落,說明BD-SOC1對(duì)酵母菌生長無影響;在SD/-Trp/-Ade/-His + X-α-gal培養(yǎng)基上,只有陽性對(duì)照(Po)長出菌斑,陰性對(duì)照(Ne)、空白對(duì)照(BD-empty)、BD-SOC1均未長出菌斑,說明DdSOC1沒有自激活現(xiàn)象。
酵母篩庫結(jié)果顯示,BD-SOC1質(zhì)粒與酵母文庫質(zhì)粒共轉(zhuǎn)入的酵母菌在QDO板上長出白色單菌落,其在QDO/X/A板上均變藍(lán)。對(duì)QDO/X/A上變藍(lán)單菌落進(jìn)行菌落PCR檢測(cè),選擇大于500 bp的條帶測(cè)序;利用NCBI BLAST以及德陽柿基因組注釋對(duì)比后從中篩選出7條候選互作蛋白(AGL14、JOINTLESS、NOVEIN、GL2、UBC7、NBS、MIOX)。
2.4 酵母雙雜交(Y2H)
酵母試驗(yàn)結(jié)果顯示,9組酵母組合在DDO培養(yǎng)基上均長出白色菌落,表明9組質(zhì)粒均成功轉(zhuǎn)入酵母菌株;在QDO及QDO/X/A培養(yǎng)基上,陰性和空白對(duì)照均無菌斑,陽性對(duì)照以及7個(gè)酵母組合均能正常生長,且可轉(zhuǎn)變?yōu)樗{(lán)色(圖4)。因此,德陽柿SOC1蛋白與AGL14、JOINTLESS、NOVEIN、GL2、UBC7、NBS、MIOX均可發(fā)生互作。
2.5 雙分子熒光互補(bǔ)(BiFC)
為驗(yàn)證DdSOC1與7個(gè)候選互作蛋白在植物體內(nèi)的互作關(guān)系,將DdSOC1和候選互作蛋白分別構(gòu)建BiFC載體pSPYNE(NE)和pSPYCE(CE),并在煙草細(xì)胞中共注射后觀察YFP熒光信號(hào)。結(jié)果(圖5)顯示,7個(gè)組合中,JOINTLESS-cYFP+SOC1-nYFP在煙草細(xì)胞的細(xì)胞核、膜中發(fā)出較強(qiáng)烈的黃色熒光;AGL14-cYFP+Dd-SOC1-nYFP組合在細(xì)胞核中發(fā)出黃色熒光;其他組合在細(xì)胞膜上顯示黃色熒光。以上情況表明DdSOC1與7個(gè)候選互作蛋白在植物體內(nèi)均存在互作關(guān)系。
2.6 DdSOC1及互作蛋白基因在德陽柿中的表達(dá)情況
探究了蕾期1年生、2年生不同性狀(已開花、未開花)德陽柿實(shí)生苗幼葉(頂芽附近葉片)、成葉(遠(yuǎn)離頂芽的成年葉)中DdSOC1及互作蛋白基因的表達(dá)情況。試驗(yàn)結(jié)果(圖6)顯示,與未開花實(shí)生苗相比,1年生已開花德陽柿實(shí)生苗的幼葉中SOC1、AGL14、NOVEIN、GL2、UBC7、NBS的表達(dá)量較成葉中高,而MIOX在幼葉的表達(dá)量則低于成葉;2年生已開花德陽柿實(shí)生苗中,幼葉中SOC1、NOVEIN表達(dá)量較成葉低,而其他基因(GL2、UBC7、NBS、AGL14、JOINTLESS)的表達(dá)量在幼葉中高于成葉;2年生未開花實(shí)生苗中,幼葉中SOC1表達(dá)量略低于成葉,其他基因(GL2、AGL14、NOVEIN、JOINTLESS、UBC7、NBS、MIOX)在幼葉中的表達(dá)量均高于成葉。
3 討 論
本研究中筆者克隆出了DdSOC1基因,預(yù)測(cè)了DdSOC1蛋白的等電點(diǎn)及分子質(zhì)量等理化性質(zhì)。進(jìn)化樹分析表明,DdSOC1蛋白與擬南芥AtSOC1、水稻OsSOC1親緣關(guān)系較遠(yuǎn),與歐洲葡萄VvSOC1、茶CsSOC1、中華獼猴桃AcSOC1等親緣關(guān)系較近,與同屬君遷子DlSOC1相似性最高,這表明SOC1在木本植物上進(jìn)化較為保守。DdSOC1的表達(dá)特征結(jié)果顯示,在整個(gè)成花過程中,葉、芽中DdSOC1表達(dá)量分別是逐漸升高和逐漸降低,莖中DdSOC1表達(dá)量先降低后升高;幼苗期DdSOC1在芽中表達(dá)量最高,蕾期在葉中表達(dá)量最高,花期在莖中表達(dá)量最高。以上結(jié)果表明,DdSOC1整合了來自葉片的開花信號(hào),以實(shí)現(xiàn)營養(yǎng)生長向生殖生長過渡的階段,而不是直接調(diào)控花器官的發(fā)育,這與歐洲葡萄(V. vinifera)、竹子(Bambusa oldhamii)、白梨(Pyrus bretschneideri)、荔枝(Litchi chinensis)的研究結(jié)果較為相似[20-23]。
在前人已探明的SOC1調(diào)控植物開花時(shí)間的網(wǎng)絡(luò)中,CO、FT、FLC、SVP、DELLA蛋白、AGL24蛋白及LFY是重要的調(diào)控因子。其中,SOC1與AGL24在植物莖頂端分生組織中相互作用形成復(fù)合物,然后結(jié)合在LFY啟動(dòng)子上激活其表達(dá)從而完成開花誘導(dǎo)[24-27]。明晰DdSOC1的成花調(diào)控網(wǎng)絡(luò),對(duì)探究DdSOC1調(diào)控德陽柿短童期分子機(jī)制具有重要意義。本研究基于富平尖柿cDNA核次級(jí)文庫對(duì)DdSOC1進(jìn)行互作蛋白的篩選,共篩選得到7個(gè)互作蛋白。Y2H和BiFC試驗(yàn)結(jié)果均驗(yàn)證了DdSOC1與7個(gè)互作蛋白之間存在互作關(guān)系。此外,GL2-cYFP + SOC1-nYFP、NOVEIN-cYFP + SOC1-nYFP、JOINTLESS-cYFP + SOC1-nYFP三個(gè)組合熒光強(qiáng)度較高,表明DdSOC1與這3個(gè)互作蛋白(GL2、NOVEIN、JOINTLESS)互作關(guān)系較緊密。后續(xù)可以通過Co-IP或Pull-down蛋白試驗(yàn)進(jìn)行進(jìn)一步驗(yàn)證。
為了進(jìn)一步探究DdSOC1及其互作蛋白在德陽柿短童期中的作用,測(cè)定了DdSOC1基因在1年生和2年生德陽柿實(shí)生苗葉片中的表達(dá)量。德陽柿短童期現(xiàn)象在德陽柿種內(nèi)也存在差異,即存在開花和未花兩種性狀,因此本研究中選取蕾期的葉片作為試驗(yàn)材料。在1年生德陽柿中,已開花實(shí)生苗幼葉SOC1表達(dá)量比成葉高,而在未開花實(shí)生苗中幼葉SOC1表達(dá)量比成葉低,這表明SOC1對(duì)德陽柿開花有著積極影響。同樣地,AGL14、JOINTLESS、NOVEIN、GL2、UBC7、NBS也表現(xiàn)出與SOC1相似的表達(dá)規(guī)律,即在1年生已開花的德陽柿的幼葉中高表達(dá),這說明以上6個(gè)互作蛋白可能對(duì)德陽柿短童期具有正調(diào)控作用;而MIOX在1年生開花德陽柿實(shí)生苗幼葉中低表達(dá),這說明其對(duì)德陽柿開花可能有阻遏作用。2年生實(shí)生苗,SOC1表達(dá)量在不同性狀的實(shí)生苗中差異不大,而AGL14、JOINTLESS、GL2、UBC7在開花實(shí)生苗中的表達(dá)量高于未開花實(shí)生苗。此外,前人研究發(fā)現(xiàn),AGL14通過促進(jìn)LFY和AP1的表達(dá)使擬南芥出現(xiàn)早花表型[28],AGL14也參與擬南芥花衰老方面的調(diào)節(jié)[29];JOINTLESS為典型的MADS-box基因,與花序分生組織發(fā)育有著密切關(guān)系,如在番茄中正調(diào)控番茄花序的分支和數(shù)量[30-31];GL2作為GL2-zip家族轉(zhuǎn)錄因子通過與ZIM結(jié)構(gòu)域蛋白CsJAZ1相互作用,進(jìn)而調(diào)控延遲黃瓜雄花的開花時(shí)間[32];MIOX參與了晚熟橙花和葉片的發(fā)育過程[33];轉(zhuǎn)錄組學(xué)分析表明,NBS在早開花紫苜蓿中高表達(dá)[34],而目前并未有關(guān)于NOVEIN、UBC7參與植物成花調(diào)控的報(bào)道。綜上,本研究中篩選得到7個(gè)互作蛋白,AGL14、JOINTLESS、GL2、NBS可能正調(diào)控德陽柿短童期性狀,MIOX可能有延遲開花的作用,而NOVEIN、UBC7可能不參與德陽柿的成花調(diào)控。
4 結(jié) 論
本研究從柿中克隆分離出DdSOC1基因,其序列在木本植物中進(jìn)化較為保守;DdSOC1可能整合了來自葉片的開花信號(hào),以此實(shí)現(xiàn)營養(yǎng)生長向生殖生長的過渡;篩選得到了DdSOC1的7個(gè)互作蛋白;AGL14、JOINTLESS、GL2、NBS可能正調(diào)控促進(jìn)德陽柿開花,MIOX可能有延遲開花的作用,而NOVEIN、UBC7可能不參與德陽柿成花調(diào)控。
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收稿日期:2024-09-26 接受日期:2024-12-04
基金項(xiàng)目:國家重點(diǎn)研發(fā)計(jì)劃(2022YFD2200403);廣西自然科學(xué)基金項(xiàng)目(2021GXNSFBA196032)
作者簡(jiǎn)介:萬建琦,在讀碩士研究生,研究方向?yàn)楣麡溆N與生物技術(shù)。E-mail:wanjianqi0101@qq.com
*通信作者Author for correspondence. E-mail:guanchangfei@nwafu.edu.cn