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糖基转移酶(glycosyltransfereases, GTs)能把不同活化糖基转移到糖链、核酸、蛋白质、脂质以及各种有机复合物等特异受体分子上,形成多糖分子和糖基化衍生物[1-2],在生物代谢中作用巨大。糖基转移酶广泛参与植物代谢反应。首先,细胞的各种重要代谢产物如糖蛋白、糖脂、核酸、淀粉和蔗糖等的糖基都必须在糖基转移酶作用下添加上去[4-5];其次,组成细胞壁的纤维素、半纤维素和果胶等细胞组分的形成都需要糖基转移酶参与[2];另外,它还可以通过调节各种植物生长调节剂的糖基化,改变生长调节剂活性,参与植物生长发育以及对逆境因子的响应过程[6-7]。植物中糖基转移酶及其相应基因功能研究对了解植物代谢效应,以及植物细胞对胞内、胞外环境的响应都有重要意义。编码该类酶的基因在基因组中成员众多,如拟南芥Arabidopsis thanliana中有450多个,水稻Oryza sativa中有600多个,杨树Populus trichocarpa中有800多个[1, 3]。该类基因通常以基因家族形式存在,目前已知的糖基转移酶家族超过90个,其中植物中有40多个[3]。植物中GT8糖基转移酶基因家族组成复杂,该基因家族成员数量众多,仅拟南芥中就有41个属于GT8家族的基因[1]。根据编码蛋白序列特征和功能,可将GT8基因家族分成2大类。一类为半乳糖醛酸转移酶(gAlac uronosyl transferase, GAUT),包括GAUT和GATL(GAUT-Like)2个子类。目前研究认为:该类基因主要参与果胶和木聚糖的生物合成,如拟南芥中GAUT1编码的蛋白为半乳糖醛酸聚糖糖基转移酶,参与果胶合成[8]。AtGAUT12的突变能大幅度降低植株中木聚糖含量[9],GUX1,GUX2和GUX5也都参与植物木聚糖合成[10],而果胶和木聚糖是细胞壁合成所必需的,表明GT8家族的基因在植物细胞壁合成中发挥重要作用[11-12]。另一类包括植物类糖原淀粉合成起始蛋白(plant glycogenin-lilke starch intiation proteins, PGSIPs)和乳糖苷合成酶(galactinol synthses, GolSs)。其中PGSIPs参与淀粉生物合成的启动[13];GolSs则是棉子糖类多糖合成的关键酶,后者能够作为渗透调节剂在植物逆境响应中发挥重要作用[14-15]。糖基转移酶家族成员众多,糖基转移酶功能特异性很强,即使添加同一个活化糖基,也可能因为受体不同而需要不同糖基转移酶来完成[5];而且,不同家族成员在功能上也存在交叉现象[16]。这些问题给糖基转移酶基因功能研究带来了很大困难。植物中糖基转移酶相关基因功能研究仍处在起步阶段,林木中此类基因的具体功能更是知之甚少。桉树Eucalyptus是世界上三大用材树种之一,其生产和地域分布极易受到低温、干旱、高温和高盐等非生物逆境因子的影响。EgrGATL1(Eucgr. I01882)是巨桉Eucalyptus grandis GT8家族中一个基因成员,前期研究中发现该基因表达受低温胁迫诱导,表明该基因可能与巨桉逆境响应有一定关系。目前一般认为植物GATL子类中的基因也主要与果胶和木聚糖生物合成有关[9, 17-18],但在水稻中也发现多个OsGATL基因受低温、干旱和ABA处理的诱导,暗示植物中GATL基因可能在非生物逆境胁迫响应中发挥了一定功能[19]。本研究从EgrGATL的序列特征和低温、干旱和高盐胁迫以及脱落酸(ABA),茉莉酸甲酯(MeJA)处理下基因表达角度上,分析了EgrGATL1与巨桉抗逆的关系,为其进一步功能的研究提供依据。
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本研究所用材料为巨桉G5无性系,来源于中国林业科学研究院热带林业研究所曾炳山研究员实验室。无性系幼苗种植于浙江农林大学苗圃地。选取苗龄3个月,长势一致的巨桉无性系幼苗作为实验材料。在植物生长箱(Snijders MC1000,荷兰)中正常培养,日温为25 ℃,夜温为22 ℃;光照/黑暗为14 h/10 h;光强为150 μmol·m-2·s-1,相对湿度为70%。
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根据基因注释编号Eucgr. I01882,从https://phytozome.jgi.doe.gov/pz/portal.html#!info?alias=Org_ Egrandis下载该基因核酸序列和蛋白序列。设计全长引物(表 1)进行聚合酶链式反应(PCR)扩增,测序验证。其编码蛋白氨基酸序列用Protparam(http://www.expasy.ch/tools)软件进行分子量、等电点分析。结构域搜寻用保守域数据库(CDD. https://www.ncbi.nlm.nih.gov/cdd)结合EgrGATL1不同植物中同源蛋白多序列比对(Clustalx)以及GT8基因家族相关基因分析文献进行[1, 20]。
表 1 实时荧光定量所用引物序列
Table 1. List of primer sequences used in RT-PCR
引物用途 引物名称 引物序列(5′→3′) 全长扩增 EgrGATL1-F CTTCTTCTTCCCATATCGCAGC EgrGATL1-F TTGATTCTCGAGCCGAACATAG qRT-PCR分析 Egr18SrRNA-qRT-F CGCGCTACACTGATGTATTC Egr18SrRNA-qRT-R GTACAAAGGGCAGGGACGTA EgrGATL1-qRT-F ATCTGCTTCCTCCTGCTCC EgrGATL1-qRT-R CCCTCAGGTACTCGAAATCC EgrGATL1进化分类按照ULVSKOV对GATL基因的分类标准[21],分别选取不同子组中相应拟南芥GATL蛋白序列,与EgrGATL1一起,用MEGA软件构建1 000个自举重复无根邻接进化树,对其作进化分类。
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3个月苗龄巨桉幼苗于4 ℃低温生长箱中,为避免由于取样时间点不同对基因表达造成影响,实验采用先后间隔0,24,36,42,46 h依次放入生长箱处理,以25 ℃生长条件下幼苗作为对照(ck)。处理完毕后一起收获叶片(摘取枝条顶芽下面第3~5片完全展开的叶片),迅速投入液氮中,提取RNA进行数字表达谱(DGE)测序(诺禾致源)。结果中差异表达基因(>2倍)用加权基因共表达网络分析(WGCNA)计算与EgrNAC1具有共表达关系基因的Pearson系数(rco),根据rco大小进行基因排序。选取rco或rco绝对值>0.9的基因,将这些基因的编码蛋白序列在UniProtKB蛋白数据库中进行Blastp(https://blast.ncbi.nlm.nih.gov/Blast.cgi)比对,在域值E值<e-5范围内筛选匹配度最好的一项提取蛋白序列编码。然后将所有注释蛋白的序列编码提交到可视化整合蛋白注释数据库(DAVID)中,对比京都基因与基因组百科全书(KEGG)进行分析(https://david.ncifcrf.gov/tools.jsp),对能够在KEGG中找到相应代谢途径的共表达基因进行统计、分析。
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参考魏晓玲等[22]的方法,在生长箱中以25 ℃生长条件下幼苗作为对照(ck),-8,-4,0,4,8和42 ℃分别处理2 h;4 ℃不同时间处理实验同1.3。处理后植株叶片迅速放入液氮,用于RNA提取。高盐处理则将植株置于不同塑料容器(60 L)内,处理组塑料容器内保持植株栽培盆1/3高度的200 mmol·L-1氯化钠溶液,对照组则用清水保持同样液面高度。同样采用间隔0,24,48,60,66 h的方法依次放入处理苗;干旱处理用5,3,2,1 d不浇水植株作为处理组,正常浇水的作为对照。100 μmol·L-1 ABA和100 μmol·L-1 MeJA处理采用植株叶面喷施的方法,ABA以喷施激素溶液后6,12,24,48 h植株作为处理组;MeJA以喷施激素溶液后2,12,24 h植株作为处理组,未喷施植株作为对照组(ck)。实验结束后,统一收获叶片,提取RNA。实验设9株·处理-1,3株·重复-1,共3个重复。
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根据王亚红等[23]的方法提取样品RNA。组织特异性表达分析以正常生长条件下苗龄3个月的巨桉根、木质部、韧皮部和叶为RNA提取材料。RNA反转录利用PrimeScrip®RT reagent Kit(TaKaRa,大连,中国)试剂盒完成。定量荧光染料SYBR-Green(Takara,大连,中国)和BIO-RAD CFX96实时PCR系统(Bio-Rad,美国)用于EgrGATL1基因的定量RT-PCR。以Egr18SrRNA作为内参基因,实验设3个重复。结果用Bio-Rad CFX Manager(Version 1.5.5.34)软件进行分析。并用GraphPad(ver 4.0)进行作图。引物序列见表 1。
Glycosyltransferases gene EgrGATL1 in Eucalyptus grandis
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摘要: EgrGATL1(Eucgr.I01882)是巨桉Eucalyptus grandis糖基转移酶GT8家族中GATL子类GATL-a子组的成员,多参与细胞壁组分如果胶、木聚糖等的生物合成。实时定量聚合酶链式反应(qRT-PCR)分析表明:EgrGATL1在木质部和韧皮部的相对表达量较高;不同低温(-8,-4,0,4,8℃)和4℃不同时间(0,2,6,12,24,48 h)处理对EgrGATL1都有强烈诱导作用。4℃不同时间处理下,EgrGATL1基因共表达产物主要参与代谢途径分析数据库(KEGG)中的糖代谢和氨基酸代谢途径。干旱胁迫对EgrGATL1有诱导作用;100 μmol·L-1茉莉酸甲酯(MeJA)处理对EgrGATL1表达呈现瞬时诱导效应;200 mmol·L-1氯化钠(NaCl)和100 μmol·L-1脱落酸(ABA)对其表达有抑制作用,而且随处理时间延长,2种处理对EgrGATL1的抑制规律有很强同步性。这些结果说明:EgrGATL1有可能通过参与细胞壁组分生物合成和ABA等植物生长调节剂活性调控,在巨桉低温、干旱和高盐等非生物逆境响应过程中发挥一定作用。Abstract: In Eucalyptus grandis, EgrGATL1 (Eucgr. I01882), a member of the glycosyltransferases 8 family belongs to the GATL subfamily, which contributes to the biosynthesis of cell wall components such as pectin and xylan, is classified as the GATL-a subgroup. In this study, the protein sequence of EgrGATL1 was analyzed and cis-elements were searched in the promoter sequence of this gene with MathInspector software. Real time fluorescence quantitative Polymerase Chain Reaction(qRT-PCR) method was used to evaluate expression pattern of EgrGATL1 under treatments of low temperatures (-8, -4, 0, 4, 8℃), time course at 4℃ (0, 2, 6, 12, 24, 48 h), drought, 100 μmol·L-1 MeJA, 200 mmol·L-1 NaCl and 100 μmol·L-1 ABA. In addition, a KEGG analysis was used to test co-expression genes of EgrGATL1 under treatment of time course at 4℃. The protein sequence analysis showed EgrGATL1 contains a typical GT8 domain. Results of expression in different tissues showed that expression of EgrGATL1 was higher in xylem and phloem than in roots and leaves. Low temperature (-8, -4, 0, 4, 8℃) and time course treatment at 4℃ both can promote the expression of EgrGATL1. With KEGG analysis, 25 genes co-expressed with EgrGATL1 can match to KEGG pathways, 11 genes belong to the sugar metabolism pathways and 8 genes were distributed to amino acid metabolism pathways. EgrGATL1 was also induced by drought and showed transient induction with the 100 μmol·L-1 MeJA treatment. And, there is no significant difference between the expression patterns of EgrGATL1 with treatments of 200 mmol·L-1 NaCl and 100 μmol·L-1 ABA. Thus, EgrGATL1 was possibly involved in cell wall remodeling and with activity of hormones such as ABA, thereby implying a possible role in low temperature, drought, and salinity stress responses in E. grandis.
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Key words:
- botany /
- Eucalyptus grandis /
- EgrGATL1 /
- abiotic stress /
- gene expression
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表 1 实时荧光定量所用引物序列
Table 1. List of primer sequences used in RT-PCR
引物用途 引物名称 引物序列(5′→3′) 全长扩增 EgrGATL1-F CTTCTTCTTCCCATATCGCAGC EgrGATL1-F TTGATTCTCGAGCCGAACATAG qRT-PCR分析 Egr18SrRNA-qRT-F CGCGCTACACTGATGTATTC Egr18SrRNA-qRT-R GTACAAAGGGCAGGGACGTA EgrGATL1-qRT-F ATCTGCTTCCTCCTGCTCC EgrGATL1-qRT-R CCCTCAGGTACTCGAAATCC -
[1] YIN Yanbin, MOHNEN D, GELINEO-ALBERSHEIM, et al. Glycosyltransferases of the GT8 Family[J]. Annu Plant Rev, 2011, 41:167-172. [2] LAIRSON LL, HENRISSAT B, DAVIES GJ, et al. Glycosyltransferases:structures, functions, and mechanisms[J]. Annu Rev Biochem, 2008, 77:521-555. [3] LAO J, OIKAWA A, BROMLEY J R, et al. The plant glycosyltransferase clone collection for functional genomics[J]. Plant J, 2014, 79(3):517-529. [4] VOGT T, JONES P. Glycosyltransferases in plant natural product synthesis:characterization of a supergene family[J]. Trends Plant Sci, 2000, 5(9):380-386. [5] CAMPBELL J A, DAVIES G J, BULONE V, et al. A classification of nucleotide-diphospho-sugar glycosyltransferases based on amino acid sequence similarities[J]. Biochem J, 1997, 326(3):929-939. [6] TIWARI P, SANGWAN R S, SANGWAN N S. Plant secondary metabolism linked glycosyltransfrases:an update on expanding knowledge and scopes[J]. Biotechnol Adv, 2016, 34(5):714-739. [7] PALANIYANDI S A, CHUNG G, KIM S H, et al. Molecular cloning and characterization of the ABA-specific glucosyltransferase gene from bean (Phaseolus vulgaris L.)[J]. J Plant Physiol, 2015, 178(2):1-9. [8] STERLING J D, ATMODJO M A, INWOOD S E, et al. Functional identification of an Arabidopsis pectin biosynthetic homogalacturonan galacturonosyltransferase[J]. Proc Nat Acad Sci USA, 2006, 103(13):5236-5241. [9] BROWN D M, GOUBET F, WONG V W, et al. Comparison of five xylan synthesis mutants reveals new insight into the mechanisms of xylan synthesis[J]. Plant J, 2007, 52(6):1154-1168. [10] RENNIE E A, HANSEN S F, BAIDOO E E, et al. Three members of the Arabidopsis glycosyltransferase family 8 are xylan glucuronosyltransferases[J]. Plant Physiol, 2012, 159(4):1408-1417. [11] COSGROVE D J. Growth of the plant cell wall[J]. Nat Rev Mol Cell Biol, 2005, 6(11):850-861. [12] PEAUCELLE A, BRAYBROOK S, HÖFTE H. Cell wall mechanics and growth control in plants:the role of pectins revisited[J]. Front Plant Sci, 2012, 3:121. doi:10.338g/fpls. 2012. 00121. [13] CHATTERJEE M, BERBEZY P, VYAS D, et al. Reduced expression of a protein homologous to glycogenin leads to reduction of starch content in Arabidopsis leaves[J]. Plant Sci, 2005, 168(2):501-509. [14] NISHIZAWA-YOKOI A, YABUTA Y, SHIGEOKA S. Galactinol and raffinose constitute a novel function to protect plants from oxidative damage[J]. Plant Physiol, 2008, 147(3):1251-1263. [15] LAO N T, LONG D, KIANG S, et al. Mutation of a family 8 glycosyltransferase gene alters cell wall carbohydrate composition and causes a humidity-sensitive semi-sterile dwarf phenotype in Arabidopsis[J]. Plant Mol Biol, 2003, 53(5):687-701. [16] COUTINHO P M, HENRISSAT B. Annotating Carbohydrateactive Enzymes in Plant Genomes:Present Challenges[M]. Oxford:Wiley-Blackwell Publishing Ltd., 2010:93-107. [17] LEE C H, ZHONG R Q, RICHARDSON E A, et al. The PARVUS gene is expressed in cells undergoing secondary wall thickening and is essential for glucuronoxylan biosynthesis[J]. Plant Cell Physiol, 2007, 48(12):1659-1672. [18] KONG Yingzhen, ZHOU Gongke, AVCI U, et al. Two poplar glycosyltransferase genes, PdGATL1.1 and PdGATL1.2, are functional orthologs to PARVUS/AtGATL1 in Arabidopsis[J]. Mol Plant, 2009, 2(5):1040-1050. [19] LIU Jinlong, LUO Mansi, YAN Xin, et al. Characterization of genes coding for galacturonosyltransferase-like (GATL) proteins in rice[J]. Genes Genom, 2016, 38(10):917-929. [20] YIN Yanbin, CHEN Huiling, HAHN M G, et al. Evolution and function of the plant cell wall synthesis-related glycosyltransferase family 8[J]. Plant Physiol, 2010, 153(4):1729-1746. [21] ULVSKOV P. Annual Plant Reviews, Plant Polysaccharides:Biosynthesis and Bioengineering[M]. New Jersey:John Wiley & Sons, 2011. DOI:10.1002/9781444391015 [22] 魏晓玲, 程龙军, 窦锦青, 等.巨桉EgrDREB2A基因结构及表达特性分析[J].林业科学, 2015, 51(2):80-89. WEI Xiaoling, CHENG Longjun, DOU Jinqing, et al. The structure and expression characteristics of EgrDREB2A gene in Eucalyputs grandis[J]. Sci Silv Sin, 2015, 51(2):80-89. [23] 王亚红, 刘缙, 王玉国.高质量提取银杏种仁RNA的改良方法[J].中国农学通报, 2010, 26(15):48-52. WANG Yahong, LIU Jin, WANG Yuguo. An improved method for RNA isolation from seeds of Ginkgo biloba L.[J]. Chin Agric Sci Bull, 2010, 26(15):48-52. [24] KONG Yingzhen, ZHOU Gongke, YIN Yanbin, et al. Molecular analysis of a family of Arabidopsis genes related to galacturonosyl transferases[J]. Plant Physiol, 2011, 155(4):1791-1805. [25] KONG Yingzhen, ZHOU Gongke, ABDEEN A A, et al. GALACTURONOSYLTRANSFERASE-LIKE5 is involved in the production of Arabidopsis seed coat mucilage[J]. Plant Physiol, 2013, 163(3):1203-1217. [26] TENHAKEN R. Cell wall remodeling under abiotic stress[J]. Front Plant Sci, 2015, 5:771. doi:10.338g/fpls. 2014. 00771. [27] QU Tangdong, LIU Rugao, WANG Weilin, et al. Brassinosteroids regulate pectin methylesterase activity and AtPME41 expression in Arabidopsis under chilling stress[J]. Cryobiology, 2011, 63(2):111-117. [28] DOMON J M, BALDWIN L, ACKET S, et al. Cell wall compositional modifications of Miscanthus ecotypes in response to cold acclimation[J]. Phytochemistry, 2013, 85(2):51-61. [29] LEUCCI M R, LENUCCI M S, PIRO G, et al. Water stress and cell wall polysaccharides in the apical root zone of wheat cultivars varying in drought tolerance[J]. J Plant Physiol, 2008, 165(11):1168-1180. [30] PAULY M, KEEGSTRA K. Cell-wall carbohydrates and their modification as a resource for biofuels[J]. Plant J, 2008, 54(4):559-568. [31] le GALL H, PHILIPPE F, DOMON J M, et al. Cell wall metabolism in response to abiotic stress[J]. Plants, 2015, 4(1):112-166. [32] GACHON C M M, LANGLOIS-MEURINNE M, SAINDRENAN P. Plant secondary metabolism glycosyltransferases:the emerging functional analysis[J]. Trends Plant Sci, 2005, 10(11):542-549. [33] BEVERIDGE C A, MURFET I C, KERHOAS L, et al. The shoot controls zeatin riboside export from pea roots:evidence from the branching mutant rms4[J]. Plant J, 1997, 11(2):339-345. [34] DONG Ting, XU Zhengyi, PARK Y M, et al. Abscisic acid uridine diphosphate glucosyltransferases play a crucial role in abscisic acid homeostasis in Arabidopsis[J]. Plant Physiol, 2014, 165(1):277-289. [35] RIEMANN M, DHAKAREY R, HAZMAN M, et al. Exploring jasmonates in the hormonal network of drought and salinity responses[J]. Front Plant Sci, 2015, 6:1077. doi:10.3389/fpls.2015.01077. -
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https://zlxb.zafu.edu.cn/article/doi/10.11833/j.issn.2095-0756.2018.04.004