摘要:低溫環(huán)境嚴重限制了植物的生長發(fā)育和作物產(chǎn)量。在長期的進化過程中,植物在分子、生理和生化水平上形成了復(fù)雜的適應(yīng)低溫脅迫的機制。其中,在分子水平上,轉(zhuǎn)錄因子是低溫脅迫信號傳導(dǎo)的主要參與者,一些轉(zhuǎn)錄因子構(gòu)成了信號網(wǎng)絡(luò)中的主要樞紐。該網(wǎng)絡(luò)中主要的轉(zhuǎn)錄因子包括MYB、bHLH、bZIP、ERF、NAC和WRKY等。人們利用基因工程、生物信息學(xué)和轉(zhuǎn)錄組學(xué)等多種生物學(xué)技術(shù),逐漸發(fā)現(xiàn)了bHLH轉(zhuǎn)錄因子在植物逆境響應(yīng)中的重要作用。bHLH轉(zhuǎn)錄因子在低溫脅迫響應(yīng)中起關(guān)鍵作用,是植物分子育種中提高低溫脅迫耐受性的寶貴基因資源。因此,闡明bHLH轉(zhuǎn)錄因子植物響應(yīng)低溫脅迫的調(diào)控機制具有重要意義。本文簡要介紹了bHLH轉(zhuǎn)錄因子的基本特征和各植物中bHLH家族成員數(shù)量,對參與低溫脅迫的bHLH轉(zhuǎn)錄因子家族成員(如ICE、MYC2)進行敘述,并闡述了bHLH轉(zhuǎn)錄因子在低溫脅迫中的調(diào)控機制,包括與下游靶基因或其他轉(zhuǎn)錄因子互作、ICE-CBF通路和活性氧(ROS)及植物激素介導(dǎo)的信號通路,為進一步提高植物抗寒性和培育抗寒新品種提供參考。
關(guān)鍵詞:bHLH轉(zhuǎn)錄因子;低溫脅迫;調(diào)控;逆境響應(yīng);抗寒性
中圖分類號:S184 文獻標志碼:A
文章編號:1002-1302(2024)16-0011-09
低溫限制了冷敏感植物的生長發(fā)育、地理分布、產(chǎn)量和品質(zhì),對植物的影響顯著大于其他環(huán)境脅迫因素[1]。低溫脅迫對植物的影響主要表現(xiàn)在光合作用減弱、水分代謝失調(diào)、酶活性降低,對植物生長和產(chǎn)量造成不可逆的傷害[2]。為了在惡劣條件下生存,許多植物通過轉(zhuǎn)錄因子調(diào)控一系列靶基因的表達來增強植物對低溫脅迫的適應(yīng)性[3]。轉(zhuǎn)錄因子根據(jù)DNA結(jié)合區(qū)域的特異性可分為多個不同的家族,與植物抗逆性相關(guān)的主要有4種:堿性亮氨酸拉鏈(bZIP)、WRKY、AP2/ERF(APETALA2/ethylene responsive factor)、MYB(V-myb avian myeloblastosis viral oncogene homolog)。堿性螺旋-環(huán)-螺旋(bHLH)轉(zhuǎn)錄因子家族在抗逆研究中相對滯后[4]。近年來隨著對bHLH轉(zhuǎn)錄因子家族研究的不斷深入,發(fā)現(xiàn)其在抵御低溫脅迫中有重要的調(diào)控作用,比如擬南芥(Arabidopsis thaliana)中的ICE1(inducer of CBF expression 1)和ICE2(inducer of CBF expression 2)、野生稻(Oryza rufipogon)中的OrbHLH001參與低溫脅迫應(yīng)答,并可構(gòu)成調(diào)控網(wǎng)絡(luò)[5-7]。本文重點綜述了bHLH轉(zhuǎn)錄因子在調(diào)控植物低溫脅迫耐受性分子機制中的作用,這些研究為提高植物的抗寒性奠定了基礎(chǔ)。
1 bHLH轉(zhuǎn)錄因子的結(jié)構(gòu)特征與分類
bHLH家族是真核生物轉(zhuǎn)錄因子中僅次于MYB的第二大家族,廣泛存在于植物中,其命名來源于其具有高度保守的堿性/螺旋-環(huán)-螺旋特殊結(jié)構(gòu)域[8]。它由2個部分組成,一部分是堿性氨基酸區(qū)域,另一部分是螺旋-環(huán)-螺旋區(qū)域(HLH)(圖1)。堿性結(jié)構(gòu)域位于bHLH的N端,包含約15個氨基酸和6個堿性殘基,其主要參與DNA與靶基因中的E-box(CANNTG)或G-box(CACGTG)基序的結(jié)合[9];HLH區(qū)域位于C端,包含40~50個氨基酸,包括2個由疏水殘基通過疏水環(huán)連接的兩親性α-螺旋。由于α-螺旋具有靈活性,可以進行結(jié)構(gòu)域二聚化以促進蛋白質(zhì)-蛋白質(zhì)相互作用,并形成同源或異源二聚體復(fù)合物來調(diào)控靶基因的表達[10]。
bHLH家族首先在小鼠肌肉發(fā)育研究中被發(fā)現(xiàn),隨后在所有真核生物包括動物、植物和真菌中被鑒定[11-12]。1989年,Ludwig等在玉米中發(fā)現(xiàn)了由R(resistance)基因編碼花青素合成的第1種植物
bHLH蛋白[13]。bHLH家族基因的數(shù)量在不同的物種之間也有差異(表1):在擬南芥(Arabidopsis thaliana)的基因組中共鑒定出162個基因(AtbHLH)[14],而在水稻(Oryza sativa)中發(fā)現(xiàn)了167個(OsbHLH),在番茄(Solanum lycopersicum)中發(fā)現(xiàn)了159個(SlbHLH),在銀杏(Ginkgo biloba)中發(fā)現(xiàn)了85個(GbbHLH),在蘋果(Malus domestica)中發(fā)現(xiàn)了188個(MdbHLH),在葡萄(Vitis vinifera)中發(fā)現(xiàn)了191個(VvbHLH)[15-19]。
1999年,Atchley等根據(jù)進化關(guān)系、與DNA的結(jié)合模式以及自身的功能特性,首次將動物bHLH分為6個亞家族(A~F)[9]。A組可以特異性結(jié)合 E-box 核心序列;B組成員可與具有CACGTG或CATGTTG特征的E-box結(jié)合;C組可以結(jié)合ACGTG或GCGTG序列;D組成員沒有基本的DNA結(jié)合區(qū)域,主要參與與其他bHLH家族蛋白的異源二聚化;E組可以優(yōu)先與具有CACGCG或CACGAG堿基的 N-box 結(jié)合;而F組成員可以結(jié)合特定的DNA靶序列,僅有1個COE家族[40]。擬南芥中首次構(gòu)建了植物bHLH的系統(tǒng)進化樹,擬南芥bHLH家族被分為12個亞家族[41]。在植物的發(fā)育過程中,某些亞家族可能起著重要的調(diào)節(jié)生物反應(yīng)的作用。
2 與低溫脅迫有關(guān)的bHLH轉(zhuǎn)錄因子
近年來,一些研究表明,bHLH轉(zhuǎn)錄因子參與冷脅迫響應(yīng)過程并發(fā)揮重要作用。ICE1編碼一個典型的MYC-like堿性螺旋-環(huán)-螺旋(bHLH)轉(zhuǎn)錄因子,是第1個被鑒定的CBF[C-repeat-binding factors,又稱DREB(dehybration responsive element binding protein)]上游調(diào)控因子,在冷信號傳導(dǎo)途徑中起關(guān)鍵作用[5]。Yang等從南亞熱帶果樹龍眼(Dimocarpus longan)中分離得到1個新的ICE-like基因DlICE1,過表達DlICE1的轉(zhuǎn)基因擬南芥的AtCBF1/AtCBF2/AtCBF3基因和冷響應(yīng)基因(AtRD29a、AtCOR15A、AtCOR47和AtKIN1)的表達水平比野生型的更高,并通過增加脯氨酸(Pro)含量、降低離子滲漏、減少丙二醛(MDA)和活性氧(ROS)積累來增強耐冷性[42]。Wang等研究發(fā)現(xiàn),StICE1在擬南芥中的過表達增強了活性氧的清除能力及CBFs和COR(cold-related)基因的表達水平。并且StICE1通過結(jié)合StLTI6A基因的啟動子,從而維持細胞膜的穩(wěn)定性,并增強了對冷脅迫的耐受性[43]。在低溫脅迫下,植物過表達SlICE1a增強了CBF/DREB及其靶基因的誘導(dǎo),增加了脯氨酸、可溶性糖的水平,從而增強了煙草(Nicotiana tabacum)對冷脅迫的耐受性[44]。Zuo等的研究表明,過表達日本結(jié)縷草(Zoysia japonica)ZjICE1的轉(zhuǎn)基因擬南芥表現(xiàn)出對冷脅迫的耐受性增強,SOD、POD活性增加,游離脯氨酸含量增加,MDA含量降低[45]。Man等研究發(fā)現(xiàn),異源表達蘿卜(Raphanus sativus)RsICE1基因提高了水稻對低溫脅迫的耐受性,表現(xiàn)為較高的存活率、較高的可溶性糖和游離脯氨酸含量、較低的電解質(zhì)滲透率和MDA含量以及較高的葉綠素含量[46]。ICE2是ICE1的旁系同源基因,也具有類似的功能。Zhang等從切花菊神馬(Chrysanthemum morifolium ‘Jinba’)中鑒定出ICE家族基因CmICE2,過表達CmICE2的擬南芥植株比野生型更耐凍,并且經(jīng)過-9 ℃低溫處理6 h后,CmICE2過表達植株中AtCBF1、AtCBF2、AtCBF4、AtCOR6.6A、AtCOR414和AtKIN1等基因的表達量也顯著上調(diào);過表達CmICE2的植株脯氨酸含量及超氧化物歧化酶(SOD)、過氧化物酶(POD)和過氧化氫酶(CAT)的活性也顯著提高[47]。異源表達來自野生山葡萄(Vitis amurensis)的2個bHLH基因VaICE1和VaICE2的轉(zhuǎn)基因擬南芥植株耐冷性增強[48]。Zuo等從日本結(jié)縷草中鑒定得到1個新的MYC型bHLH轉(zhuǎn)錄因子ZjICE2,在擬南芥中過表達ZjICE2增強了其對冷、干旱和鹽脅迫的耐受性[49]。Fursova等從擬南芥中鑒定得到1個新的正調(diào)控低溫脅迫的bHLH家族轉(zhuǎn)錄因子ICE2,在轉(zhuǎn)基因擬南芥植株中過表達ICE2,冷馴化后對低溫脅迫的耐受性增強。過表達ICE2的轉(zhuǎn)基因株系的種子表現(xiàn)為碳水化合物水平降低和脂質(zhì)水平升高[6]。
除ICE蛋白外,bHLH轉(zhuǎn)錄因子家族的其他一些成員也參與植物的低溫脅迫。煙草NtbHLH123是一種轉(zhuǎn)錄激活因子,可與NtCBF基因啟動子中的G-box/E-box基序結(jié)合,調(diào)控ROS清除相關(guān)和脅迫響應(yīng)基因的表達,從而提高抗寒性[50]。Wang等研究發(fā)現(xiàn),在王林蘋果(Malus domestica ‘Orin’)愈傷組織中過表達MdMYC2提高了MdCIbHLH1、MdCBF1、MdCBF2和MdCBF3的表達水平,從而提高了其抗凍性[51]。Wang等研究發(fā)現(xiàn),TaMYC2在低溫脅迫響應(yīng)中起正調(diào)控作用。過表達TaMYC2提高了擬南芥抗凍性,包括積累脯氨酸含量和增加ROS清除活性[52]。從我國野生山葡萄耐寒種質(zhì)黑龍江實生苗中鑒定得到的葡萄bHLH轉(zhuǎn)錄因子VabHLH1和歐洲葡萄赤霞珠(V. vinifera ‘Cabernet Sauvignon’)中鑒定得到的bHLH轉(zhuǎn)錄因子VvbHLH1作為轉(zhuǎn)錄激活因子參與了低溫脅迫。在轉(zhuǎn)基因擬南芥植株中過表達VabHLH1和VvbHLH1轉(zhuǎn)錄因子不影響轉(zhuǎn)基因擬南芥的生長發(fā)育,但增強了其對低溫脅迫的耐受性[53]。異源表達MdCIbHLH1基因增強了轉(zhuǎn)基因擬南芥和轉(zhuǎn)基因煙草的耐冷性[54]。在轉(zhuǎn)基因煙草中過表達秋子梨(Pyrus ussuriensis)PubHLH1,增強了對冷脅迫的耐受性。過表達PubHLH1的轉(zhuǎn)基因株系表現(xiàn)為較高的存活率、較高的葉綠素含量和脯氨酸含量、較低的電解質(zhì)滲透率和MDA含量[55]??嗍w麥(Fagopyrum tataricum)FtbHLH2是一個冷相關(guān)轉(zhuǎn)錄因子,在增強冷脅迫耐受性中發(fā)揮正調(diào)控作用。在擬南芥中過表達FtbHLH2通過上調(diào)相關(guān)酶的表達,提高轉(zhuǎn)基因植株對低溫脅迫的抗性[56]。辣椒(Capsicum annuum)CabHLH79通過調(diào)控抗氧化系統(tǒng)酶(SOD、POD和CAT)和抗寒相關(guān)基因(AtRD29a、AtERD15和AtCBF1)的表達來增強抗寒性[57]。
最新研究發(fā)現(xiàn),屬于bHLH轉(zhuǎn)錄因子家族Ⅶ類轉(zhuǎn)錄因子的光敏色素互作因子PIFs也參與了植物的低溫脅迫。Lee等研究發(fā)現(xiàn),CBF途徑會受到光周期的調(diào)控,黎明后8 h,短日照(SD)植株的CBF轉(zhuǎn)錄水平是長日照(LD)植株的3~5倍,SD植株的抗凍性大于LD植株,并且光敏色素B(PHYB)和2個光敏色素互作因子PIF4和PIF7在低溫脅迫下下調(diào)了CBF途徑和耐凍性[58]。Jiang等研究發(fā)現(xiàn),PIF3通過直接結(jié)合CBF基因的啟動子來下調(diào)其表達,從而作為擬南芥抗凍性的負調(diào)節(jié)因子發(fā)揮作用[59]。甜橙(Citrus sinensis)中一個光敏色素互作轉(zhuǎn)錄因子(PIF)基因(CsPIF8)在低溫脅迫下顯著上調(diào),過表達CsPIF8提高了轉(zhuǎn)基因番茄植株和轉(zhuǎn)基因葡萄柚愈傷組織的耐冷性[60]。SlPIF4通過直接結(jié)合SlCBF基因的啟動子并激活其表達來正向調(diào)控番茄的耐冷性[61]。Cordeiro等在水稻中鑒定了一種光敏色素互作因子OsPIF14,它與OsDREB1B啟動子結(jié)合,下調(diào)了水稻原生質(zhì)體中OsDREB1B的表達[62]。He等通過ChIP-qPCR分析、酵母雙雜交試驗、表達模式分析等試驗發(fā)現(xiàn),光敏色素(phyB)缺失通過OsPIL16正向調(diào)節(jié)OsDREB1表達以增強細胞膜完整性并降低丙二醛濃度,從而提高phyB突變體的耐寒性[63]。還有其他的bHLH轉(zhuǎn)錄因子參與調(diào)控低溫脅迫,詳見表2。
3 bHLH轉(zhuǎn)錄因子在植物低溫脅迫中的調(diào)控機制
3.1 與下游靶基因或其他轉(zhuǎn)錄因子互作
bHLH轉(zhuǎn)錄因子是一類含有保守的bHLH結(jié)構(gòu)域的蛋白質(zhì)家族,是參與DNA結(jié)合的基序。bHLH蛋白在這些基因的啟動子區(qū)域通過序列特異性相互作用調(diào)控下游基因[91]。在擬南芥中AtICE1/AtbHLH116[JP+1]蛋白在低溫環(huán)境下與CBF啟動子區(qū)域結(jié)合影響轉(zhuǎn)錄起始,過表達AtICE1/AtbHLH116的植株對低溫表現(xiàn)出更高的耐受性[5]。而Hu等研究發(fā)現(xiàn),AtJAZ1和AtJAZ4可以與AtICE1/AtICE2互作,抑制AtICE的穩(wěn)定性及其下游CBF的表達,從而負調(diào)控擬南芥耐冷性[92]。Wang等研究發(fā)現(xiàn),TaMYC2與TaICE41互作激活下游CBF-COR途徑,從而提高植物的抗凍性。TaJAZ7可能與TaMYC2互作抑制TaICE41的轉(zhuǎn)錄活性或直接干擾TaICE41抑制TaICE41基因的表達,從而負調(diào)控植物耐凍性[52]。PuICE1可以通過與PuHP1互作提高PuDREBa的轉(zhuǎn)錄表達,從而提高秋子梨的抗寒性[72]。PtrMYC2與PtrBADH-I互作可以提高甘氨酸和甜菜堿的含量,從而提高枳(Poncirus trifoliata)的耐冷性[81]。Feng等通過EMSA和ChIP-PCR驗證了MdCIbHLH1蛋白與AtCBF3和MdCBF2基因啟動子中的MYC識別序列特異性結(jié)合[54]。Xie等在探究MdbHLH3調(diào)控低溫誘導(dǎo)的蘋果花青素積累和果實著色的分子機制中,進行了酵母雙雜交試驗和雙分子熒光互補試驗,發(fā)現(xiàn)MdbHLH3與MdMYB1之間存在特異性互作關(guān)系[66]。
3.2 ICE-CBF通路
為了快速感知和響應(yīng)低溫脅迫,植物進化出一系列復(fù)雜且精確的生理、生化和分子機制來響應(yīng)這種脅迫。其中,依賴于CBF的途徑是植物中最重要的冷信號途徑。CBF又稱脫水應(yīng)答元件結(jié)合因子1(DREB1),屬于AP2/EREBP轉(zhuǎn)錄因子家族,是冷信號途徑中的核心轉(zhuǎn)錄因子[93]。CBF基因的表達受冷脅迫快速誘導(dǎo),與COR基因啟動子中的脫水應(yīng)答元件(CRT/DRE)結(jié)合,激活COR基因表達,增強植物的抗寒性[5]。CBF受多個轉(zhuǎn)錄因子調(diào)控,其中CBF誘導(dǎo)因子(inducer of CBF,ICE)被認為是CBF的主要調(diào)控因子。ICE1與CBF啟動子中的MYC結(jié)合位點(CANNTG)結(jié)合。ICE1蛋白的功能主要受翻譯后修飾(post-translational modification,PTM)的調(diào)控[42]。ICE1蛋白中的PTM主要包括泛素化、SUMO化和磷酸化。編碼一個RING型泛素E3連接酶的HOS1(high expression of osmotically responsive genes 1)直接與ICE1蛋白相互作用并多聚泛素化導(dǎo)致該蛋白通過26S蛋白酶體途徑(26S proteasome pathway)降解[94]。SUMO E3連接酶SIZ1介導(dǎo)ICE1的SUMO化修飾,同時減弱HOS1對該蛋白的泛素化,以增強ICE蛋白的穩(wěn)定性,從而通過其下游CBF網(wǎng)絡(luò)增強植物的耐凍性[95]。Zhang等研究發(fā)現(xiàn),OsMAPK3磷酸化OsICE1后,OsICE1直接調(diào)控OsTPP1的表達,從而促進海藻糖合成,正調(diào)控水稻耐寒性[65]。來自蘿卜的脅迫反應(yīng)基因RsICE1在提高水稻耐冷性方面發(fā)揮積極作用,可能是通過與RsICE1基因互作上調(diào)OsDREBL和OsTPP1在低溫脅迫下的表達水平[46]。Yang等研究發(fā)現(xiàn),在低溫條件下,MdbHLH4通過直接與MdCBF1和MdCBF3啟動子結(jié)合來抑制其表達,從而負調(diào)控蘋果耐寒性。它還與MdCICE1L相互作用,并抑制MdICE1L與MdCBF1/MdCBF3啟動子的結(jié)合,從而抑制其表達[67]。
3.3 ROS及植物激素介導(dǎo)的信號通路
冷脅迫會引起超氧陰離子自由基(O-2·)、過氧化氫(H2O2)和羥基自由基(·OH)等ROS的過量積累,對細胞中的蛋白質(zhì)、脂質(zhì)和核酸具有高反應(yīng)性和毒性,最終導(dǎo)致細胞死亡。清除過量ROS是應(yīng)對冷脅迫的必要手段之一。植物進化出高效的酶促和非酶促抗氧化系統(tǒng)來保護自身免受氧化損傷。酶促抗氧化系統(tǒng)包括超氧化物歧化酶(SOD)、過氧化物酶(POD)、過氧化氫酶(CAT)、抗壞血酸過氧化物酶(APX)、谷胱甘肽過氧化物酶(GPX)、脫氫抗壞血酸還原酶(DHAR)、單脫氫抗壞血酸還原酶(MDHAR)、谷胱甘肽還原酶(GR)、谷胱甘肽S-轉(zhuǎn)移酶(GST)等[96]。在低溫脅迫前后,編碼ROS清除酶基因(NtAPX、NtSOD和NtCAT)的轉(zhuǎn)錄水平在PubHLH1過表達株系中上調(diào)[55]。NtbHLH123過表達植株在冷脅迫下表現(xiàn)出更低的電解質(zhì)外滲率,降低丙二醛含量,減少H2O2和ROS的積累,這有助于緩解冷脅迫處理后細胞膜的氧化損傷[50]。Geng等研究發(fā)現(xiàn),CsbHLH18介導(dǎo)的耐冷性可能至少部分是通過直接或間接調(diào)控抗氧化基因(CsPOD、CsSOD、CsCAT)來調(diào)節(jié)抗氧化系統(tǒng)[76]。Luo等從多花薔薇(Rosa multiflora)中分離得到RmICE1,在煙草中過表達RmICE1通過調(diào)節(jié)抗氧化酶系統(tǒng)介導(dǎo)的ROS清除和脅迫響應(yīng)基因的表達來增強抗寒性[77]。非酶促抗氧化系統(tǒng)包括還原型谷胱甘肽(GSH)、類胡蘿卜素、抗壞血酸(AsA)、類黃酮、花青素、生育酚/維生素E等[96]。低溫條件下,MdbHLH3通過調(diào)控花青素合成基因MdDFR和MdU-FGT的表達提高花青素的積累,從而提高蘋果植株的抗寒性[66]。番茄中參與花青素合成調(diào)控的AH(Hoffmans Anthocyaninless)基因編碼1個與矮牽牛(Petunia hybrida)AN1和TT8具有高度序列同源性的bHLH蛋白,通過促進低溫環(huán)境下花青素的合成,提高植物對低溫的耐受性。此外,與AH過表達株系相比,AH突變體在低溫條件下表現(xiàn)出更多的ROS積累和組成型激活的防御反應(yīng),表明AH在抵御低溫脅迫中起關(guān)鍵作用[74]。Miura等為鑒定SlICE1的功能,構(gòu)建過表達番茄株系,同源表達SlICE1基因通過增強冷響應(yīng)基因SlCBF1和SlDRCi7的表達以及抗壞血酸的積累,以提高番茄的耐冷性[73]。
植物激素茉莉酸(JA)作為脂肪酸代謝的衍生物,廣泛存在于植物中,它可以通過與其他激素或轉(zhuǎn)錄因子相互作用完成多種生物過程的調(diào)控,在調(diào)節(jié)植物生長、發(fā)育和抗逆等方面發(fā)揮著重要的作用。JA信號通路核心轉(zhuǎn)錄因子MYC2在調(diào)控植物耐寒中發(fā)揮了不可或缺的作用[51]。Zhao等首次報道了關(guān)于MYC2與ICE1的相互作用,在香蕉(Musa acuminaa)中,JA信號調(diào)控因子MaMYC2s與MaICE1相互作用,MeJA顯著誘導(dǎo)了ICE-CBF冷響應(yīng)途徑基因MaCBF1、MaCBF2、MaCOR1、MaKIN2、MaRD2和MaRD5的表達,從而增強其抗寒性[85]。Ming等研究發(fā)現(xiàn),由于JA的誘導(dǎo),PtrMYC2與PtrBADH-1的啟動子結(jié)合并激活其表達促進甜菜堿的生物合成,從而提高枳的耐冷性[81]。Min等研究發(fā)現(xiàn),SlMYC2可能是通過改善抗氧化酶系統(tǒng)和增加脯氨酸和番茄紅素水平參與了MeJA介導(dǎo)果實的耐寒性(圖2)[97]。
4 展望
作為真核生物中存在最廣泛的轉(zhuǎn)錄因子之一,bHLH家族成員眾多,功能豐富。越來越多的證據(jù)表明,bHLH轉(zhuǎn)錄因子在調(diào)節(jié)植物的低溫脅迫應(yīng)答反應(yīng)中起著關(guān)鍵作用。bHLH轉(zhuǎn)錄因子通過特異性結(jié)合脅迫相關(guān)基因啟動子區(qū)的順式作用元件,來調(diào)控其轉(zhuǎn)錄表達,從而調(diào)節(jié)植物低溫應(yīng)激反應(yīng)。本文基于bHLH的結(jié)構(gòu)特征與分類,綜述了其在調(diào)控靶基因和參與信號通路中的作用。但目前,關(guān)于bHLH轉(zhuǎn)錄因子在調(diào)控植物響應(yīng)低溫脅迫中的作用研究還不夠深入,特別是在轉(zhuǎn)錄和蛋白水平。未來可以通過轉(zhuǎn)錄調(diào)控因子與其他因子協(xié)同作用,轉(zhuǎn)錄后和翻譯后修飾等方式研究bHLH轉(zhuǎn)錄因子的功能。借助高通量測序、全基因組關(guān)聯(lián)分析和蛋白質(zhì)組學(xué)分析等生物技術(shù),可以了解不同的bHLH相關(guān)網(wǎng)絡(luò),解釋植物對低溫脅迫的響應(yīng)機制。鑒于此,bHLH可以被利用并應(yīng)用于培育抗逆性提高的作物品種方面。
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基金項目:寧夏自然科學(xué)基金(編號:2022AAC03010);寧夏重點研發(fā)計劃(編號:2022BBF03004)。
作者簡介:李 珊(2000—),女,湖南衡陽人,碩士,主要從事果樹分子育種相關(guān)研究。E-mail:lshanym@163.com。
通信作者:尹 曉,博士,講師,主要從事果樹分子育種教學(xué)和相關(guān)研究。E-mail:yinxiao90@nxu.edu.cn。