胡杨NAC转录因子PeNAC045基因的克隆及功能分析
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摘要
NAC(NAM、ATAF1/2和CUC2)域蛋白是植物特有的最大的转录因子家族之一,在调节衰老,细胞分裂,木质形成,生物和非生物胁迫等方面发挥重要作用。本研究从胡杨中成功克隆出与胁迫相关的基因,并命名为PeNAC045。测序结果表明,PeNAC045基因编码区长度为915 bp,编码304个氨基酸,与毛果杨PtrNAC045的氨基酸一致性为96.05%。对PeNAC045基因在NaCl和干旱胁迫下的表达情况进行了分析,PeNAC045基因的表达受高盐和干旱的强烈诱导。利用PeNAC045的cDNA全长构建表达载体pBI121-PeNAC045-GFP,测序确认后,将重组结构和阳性对照(空载体)分别转化野生型拟南芥(Col-0),进行亚细胞定位观察,结果显示PeNAC045-GFP融合蛋白定位于细胞核上,并由DAPI进行核染色标定。利用农杆菌花序侵染法将构建的表达载体pCAMBIA1301-Pe NAC045转化野生型拟南芥和突变体(ataf2),通过PCR鉴定,获得过表达植株及ataf2/PeNAC045回补株系。对各株系进行NaCl胁迫处理,分析PeNAC045基因的生物学功能。在150 mmol/L NaCl胁迫下,相比于拟南芥突变体和野生型植株,拟南芥PeNAC045过表达株系的萌发率降低,根长变短。此外,拟南芥PeNAC045过表达株系的株高明显低于其他株系,其在苗期对盐胁迫的敏感性增加。研究结果表明,在盐胁迫下,PeNAC045作为转录调节因子,负调控胁迫相关基因的表达。
NAC( NAM,ATAF1 /2 and CUC2) domain proteins constitute one of the largest plant-specific transcription factors( TFs) and play an important role in regulating senescence,cell division,wood formation and biotic and abiotic stresses. In present study,we successfully isolated a stress responsive gene from Populus euphratica, i. e., PeNAC045. Sequencing results indicated that the length of Pe NAC045 is 915 bp encoding 304 amino acids,and PeNAC045 shares 96. 05% homology in amino acid sequence with PtrNAC045. The expression of Pe NAC045 in response to Na Cl and drought stress was characterized. PeNAC045 mRNA expression was strongly induced by high-salinity and drought treatment.The expression vector p BI121-PeNAC045-GFP was constructed using the full-length PeNAC045 cDNA cloned into the p BI121-GFP vector. After sequencing confirmation,the construct and positive control( empty vector) were transformed into Arabidopsis. Subcellular localization experiments in Arabidopsis indicated that the PeNAC045-GFP fusion protein was localized in the nucleus. Arabidopsis was stained with the DNA dye 4,6-diamidino-2-phenylindole( DAPI) to visualize the nucleus. The expression vector pCAMBIA1301-Pe NAC045 was constructed and transformed into Arabidopsis thaliana wild type( Col-0)and ataf2 mutant using floral dip method. Then,we obtained the PeNAC045 overexpression lines of Arabidopsis and ataf2 / PeNAC045. To test the function of PeNAC045,each line was treated with NaCl.The germination percentage of Pe NAC045 overexpression lines of Arabidopsis was reduced and the root length was shorter under 150 mmol / L NaCl stress,compared to ataf2 mutant and wild-type plants.Furthermore,the sensitivity of transgenic PeNAC045 overexpression lines to NaCl stress was increased at the seedling stage and the height of the seedlings was significantly lower than others. Our results indicated that PeNAC045,as a transcriptional regulator,negatively regulates the expression of stress responsive genes under NaCl stress.
NAC( NAM,ATAF1 /2 and CUC2) domain proteins constitute one of the largest plant-specific transcription factors( TFs) and play an important role in regulating senescence,cell division,wood formation and biotic and abiotic stresses. In present study,we successfully isolated a stress responsive gene from Populus euphratica, i. e., PeNAC045. Sequencing results indicated that the length of Pe NAC045 is 915 bp encoding 304 amino acids,and PeNAC045 shares 96. 05% homology in amino acid sequence with PtrNAC045. The expression of Pe NAC045 in response to Na Cl and drought stress was characterized. PeNAC045 mRNA expression was strongly induced by high-salinity and drought treatment.The expression vector p BI121-PeNAC045-GFP was constructed using the full-length PeNAC045 cDNA cloned into the p BI121-GFP vector. After sequencing confirmation,the construct and positive control( empty vector) were transformed into Arabidopsis. Subcellular localization experiments in Arabidopsis indicated that the PeNAC045-GFP fusion protein was localized in the nucleus. Arabidopsis was stained with the DNA dye 4,6-diamidino-2-phenylindole( DAPI) to visualize the nucleus. The expression vector pCAMBIA1301-Pe NAC045 was constructed and transformed into Arabidopsis thaliana wild type( Col-0)and ataf2 mutant using floral dip method. Then,we obtained the PeNAC045 overexpression lines of Arabidopsis and ataf2 / PeNAC045. To test the function of PeNAC045,each line was treated with NaCl.The germination percentage of Pe NAC045 overexpression lines of Arabidopsis was reduced and the root length was shorter under 150 mmol / L NaCl stress,compared to ataf2 mutant and wild-type plants.Furthermore,the sensitivity of transgenic PeNAC045 overexpression lines to NaCl stress was increased at the seedling stage and the height of the seedlings was significantly lower than others. Our results indicated that PeNAC045,as a transcriptional regulator,negatively regulates the expression of stress responsive genes under NaCl stress.
引文
[1]NURUZZAMAN M,SHARONI A M,KIKUCHI S.Roles of NAC transcription factors in the regulation of biotic and abiotic stress responses in plants[J].Frontiers in Microbiology,2013,4:248.
[2]ERNST H A,OLSEN A N,SKRIVER K,et al.Structure of the conserved domain of ANAC,a member of the NAC family of transcription factors[J].Embo Reports,2004,5(3):297--303.
[3]DUVAL M,HSIEH T F,KIM S Y,et al.Molecular characterization of At NAM:a member of the Arabidopsis NAC domain superfamily[J].Plant Molecular Biology,2002,50(2):237--248.
[4]AIDA M,ISHIDA T,FUKAKI H,et al.Genes involved in organ separation in Arabidopsis:an analysis of the cup-shaped cotyledon mutant[J].Plant Cell,1997,9(6):841-857.
[5]OLSEN A N,ERNST H A,LO LEGGIO L,et al.NAC transcription factors:structurally distinct,functionally diverse[J].Trends in Plant Science,2005,10(2):79-87.
[6]SU H Y,ZHANG S Z,YUAN X W,et al.Genome-wide analysis and identification of stress-responsive genes of the NAM-ATAF1,2-CUC2 transcription factor family in apple[J].Plant Physiology and Biochemistry,2013,71:11--21.
[7]WANG Z Y,RASHOTTE A M,MOSS A G,et al.Two NAC transcription factors from Citrullus colocynthis,Cc NAC1,Cc NAC2implicated in multiple stress responses[J].Acta Physiologiae Plantarum,2014,36(3):621--634.
[8]LIU G Z,LI X L,JIN S X,et al.Overexpression of rice NAC gene SNAC1 improves drought and salt tolerance by enhancing root development and reducing transpiration rate in transgenic cotton[J].PLo S One,2014,9(1):e86895.
[9]LI W,HUANG G Q,ZHOU W,et al.A cotton(Gossypium hirsutum)gene encoding a NAC transcription factor is involved in negative regulation of plant xylem development[J].Plant Physiology and Biochemistry,2014,83:134--141.
[10]FAN K,WANG M,MIAO Y,et al.Molecular evolution and expansion analysis of the NAC transcription factor in Zea mays[J].PLo S One,2014,9(11):e111837.
[11]ZHOU Y,HUANG W F,LIU L,et al.Identification and functional characterization of a rice NAC gene involved in the regulation of leaf senescence[J].BMC Plant Biology,2013,13(1):132.
[12]WANG J Y,WANG J P,HE Y.A Populus euphratica NAC protein regulating Na+/K+homeostasis improves salt tolerance in Arabidopsis thaliana[J].Gene,2013,521(2):265-273.
[13]RIECHMANN J L,HEARD J,MARTIN G,et al.Arabidopsis transcription factors:genome-wide comparative analysis among eukaryotes[J].Science,2000,290:2105--2110.
[14]NURUZZAMAN M,MANIMEKALAI R,SHARONI A M,et al.Genome-wide analysis of NAC transcription factor family in rice[J].Gene,2010,465(1--2):30-44.
[15]HU R B,QI G A,KONG Y Z,et al.Comprehensive analysis of NAC domain transcription factor gene family in Populus trichocarpa[J].Bmc Plant Biology,2010,10(1):145.
[16]TRAN L S P,NAKASHIMA K,SAKUMA Y,et al.Isolation and functional analysis of Arabidopsis stress-inducible NAC transcription factors that bind to a drought-responsive cis-element in the early responsive to dehydration stress 1 promoter[J].Plant Cell,2004,16(9):2481-2498.
[17]LU P L,CHEN N Z,AN R,et al.A novel drought-inducible gene,ATAF1,encodes a NAC family protein that negatively regulates the expression of stress-responsive genes in Arabidopsis[J].Plant Molecular Biology,2007,63(2):289-305.
[18]JENSEN M K,LINDEMOSE S,DE MASI F,et al.ATAF1transcription factor directly regulates abscisic acid biosynthetic gene NCED3 in Arabidopsis thaliana[J].Febs Open Bio,2013,3:321-327.
[19]OH S K,LEE S,YU S,et al.Expression of a novel NAC domaincontaining transcription factor(Ca NAC1)is preferentially associated with incompatible interactions between chili pepper and pathogens[J].Planta,2005,222(5):876--887.
[20]DELESSERT C,WILSON I W,VAN DER STRAETEN D,et al.Spatial and temporal analysis of the local response to wounding in Arabidopsis leaves[J].Plant Molecular Biology,2004,55(2):165--181.
[21]DELESSERT C,KAZAN K,WILSON I W,et al.The transcription factor ATAF2 represses the expression of pathogenesisrelated genes in Arabidopsis[J].Plant Journal,2005,43(5):745--757.
[22]WANG X,CULVER J N.DNA binding specificity of ATAF2,a NAC domain transcription factor targeted for degradation by tobacco mosaic virus[J].Bmc Plant Biology,2012,12(1):157.
[23]HUH S U,LEE S B,KIM H H,et al.ATAF2,a NAC transcription factor,binds to the promoter and regulates NIT2 gene expression involved in auxin biosynthesis[J].Molecules and Cells,2012,34(3):305--313.
[24]ZHONG R Q,LEE C H,YE Z H.Functional characterization of poplar wood-associated NAC domain transcription factors[J].Plant Physiology,2010,152(2):1044-1055.
[25]ZHAO Y J,SUN J Y,XU P,et al.Intron-mediated alternative splicing of WOOD-ASSOCIATED NAC TRANSCRIPTION FACTOR1B regulates cell wall thickening during fiber development in Populus species[J].Plant Physiology,2014,164(2):765--776.
[26]GU R S,LIU Q L,PEI D,et al.Understanding saline and osmotic tolerance of Populus euphratica suspended cells[J].Plant Cell Tissue and Organ Culture,2004,78(3):261-265.
[27]LI B S,YIN W L,XIA X L.Identification of microRNAs and their targets from Populus euphratica[J].Biochemical and Biophysical Research Communications,2009,388(2):272--277.
[28]马洪双,夏新莉,尹伟伦.建立胡杨抗逆研究的c DNA-AFLP反应体系[J].北京林业大学学报,2010,32(5):34-40.MA H S,XIA X L,YIN W L.Constructing c DNA-AFLP reaction system of abiotic stress study for Populus euphratica[J].Journal of Beijing Forestry University,2010,32(5):34-40.
[29]段中鑫,覃玉蓉,夏新莉,等.超量表达胡杨peu-MIR156j基因增强拟南芥耐盐性[J].北京林业大学学报,2012,33(6):1--7.DUAN Z X,QIN Y R,XIA X L,et al.Overexpression of Populus euphratica peu-MIR156j gene enhancing salt tolerance in Arabidopsis thaliana[J].Journal of Beijing Forestry University,2012,33(6):1--7.
[30]马洪双,夏新莉,尹伟伦.胡杨SCL7基因及其启动子片段的克隆与分析[J].北京林业大学报,2011,33(1):1--10.MA H S,XIA X L,YIN W L.Cloning and analysis of SCL7 gene from Populus euphratica[J].Journal of Beijing Forestry University,2011,33(1):1--10.
[31]覃玉蓉,夏新莉,尹伟伦.实时荧光定量PCR检测miR169g在脱水与高盐胁迫下胡杨叶中的表达[J].现代仪器,2011,17(3):28--30.QIN Y R,XIA X L,YIN W L.Expression determination of miR169g under dehydration and high salinity stress in Populus euphratica leaves by real-time quantitative PCR[J].Modern Instruments,2011,17(3):28-30.
[32]OHTANI M,NISHIKUBO N,XU B,et al.A NAC domain protein family contributing to the regulation of wood formation in poplar[J].Plant Journal,2011,67(3):499--512.
[33]GOODSTEIN D M,SHU S Q,HOWSON R,et al.Phytozome:a comparative platform for green plant genomics[J].Nucleic Acids Research,2012,40(D1):1178--1186.
[34]SAITOU N,NEI M.The neighbor-joining method:a new method for reconstructing phylogenetic trees[J].Molecular Biology and Evolution,1987,4(4):406--425.
[35]WANG H L,CHEN J H,TIAN Q Q,et al.Identification and validation of reference genes for Populus euphratica gene expression analysis during abiotic stresses by quantitative real-time PCR[J].Physiologia Plantarum,2014,152(3):529--545.
[36]ZHANG X R,HENRIQUES R,LIN S S,et al.Agrobacteriummediated transformation of Arabidopsis thaliana using the floral dip method[J].Nature Protocols,2006,1(2):641--646.
[37]JEONG J S,KIM Y S,BAEK K H,et al.Root-specific expression of Os NAC10 improves drought tolerance and grain yield in rice under field drought conditions[J].Plant Physiology,2010,153(1):185-197.
[38]SONG S Y,CHEN Y,CHEN J,et al.Physiological mechanisms underlying Os NAC5-dependent tolerance of rice plants to abiotic stress[J].Planta,2011,234(2):331-345.
[39]LU M,YING S,ZHANG D F,et al.A maize stress-responsive NAC transcription factor,Zm SNAC1,confers enhanced tolerance to dehydration in transgenic Arabidopsis[J].Plant Cell Reports,2012,31(9):1701-1711.
[40]HU H H,YOU J,FANG Y J,et al.Characterization of transcription factor gene SNAC2 conferring cold and salt tolerance in rice[J].Plant Molecular Biology,2008,67(1-2):169-181.
[41]CHEN S L,LI J K,WANG S S,et al.Effects of Na Cl on shoot growth,transpiration,ion compartmentation,and transport in regenerated plants of Populus euphratica and Populus tomentosa[J].Canadian Journal of Forest Research,2003,33(6):967--975.
[42]OTTOW E A,BRINKER M,TEICHMANN T,et al.Populus euphratica displays apoplastic sodium accumulation,osmotic adjustment by decreases in calcium and soluble carbohydrates,and develops leaf succulence under salt stress[J].Plant Physiology,2005,139(4):1762--1772.
[43]HAN X,TANG S,AN Y,et al.Overexpression of the poplar NFYB7 transcription factor confers drought tolerance and improves water-use efficiency in Arabidopsis[J].Journal of Experimental Botany,2013,64(14):4589-4601.
[2]ERNST H A,OLSEN A N,SKRIVER K,et al.Structure of the conserved domain of ANAC,a member of the NAC family of transcription factors[J].Embo Reports,2004,5(3):297--303.
[3]DUVAL M,HSIEH T F,KIM S Y,et al.Molecular characterization of At NAM:a member of the Arabidopsis NAC domain superfamily[J].Plant Molecular Biology,2002,50(2):237--248.
[4]AIDA M,ISHIDA T,FUKAKI H,et al.Genes involved in organ separation in Arabidopsis:an analysis of the cup-shaped cotyledon mutant[J].Plant Cell,1997,9(6):841-857.
[5]OLSEN A N,ERNST H A,LO LEGGIO L,et al.NAC transcription factors:structurally distinct,functionally diverse[J].Trends in Plant Science,2005,10(2):79-87.
[6]SU H Y,ZHANG S Z,YUAN X W,et al.Genome-wide analysis and identification of stress-responsive genes of the NAM-ATAF1,2-CUC2 transcription factor family in apple[J].Plant Physiology and Biochemistry,2013,71:11--21.
[7]WANG Z Y,RASHOTTE A M,MOSS A G,et al.Two NAC transcription factors from Citrullus colocynthis,Cc NAC1,Cc NAC2implicated in multiple stress responses[J].Acta Physiologiae Plantarum,2014,36(3):621--634.
[8]LIU G Z,LI X L,JIN S X,et al.Overexpression of rice NAC gene SNAC1 improves drought and salt tolerance by enhancing root development and reducing transpiration rate in transgenic cotton[J].PLo S One,2014,9(1):e86895.
[9]LI W,HUANG G Q,ZHOU W,et al.A cotton(Gossypium hirsutum)gene encoding a NAC transcription factor is involved in negative regulation of plant xylem development[J].Plant Physiology and Biochemistry,2014,83:134--141.
[10]FAN K,WANG M,MIAO Y,et al.Molecular evolution and expansion analysis of the NAC transcription factor in Zea mays[J].PLo S One,2014,9(11):e111837.
[11]ZHOU Y,HUANG W F,LIU L,et al.Identification and functional characterization of a rice NAC gene involved in the regulation of leaf senescence[J].BMC Plant Biology,2013,13(1):132.
[12]WANG J Y,WANG J P,HE Y.A Populus euphratica NAC protein regulating Na+/K+homeostasis improves salt tolerance in Arabidopsis thaliana[J].Gene,2013,521(2):265-273.
[13]RIECHMANN J L,HEARD J,MARTIN G,et al.Arabidopsis transcription factors:genome-wide comparative analysis among eukaryotes[J].Science,2000,290:2105--2110.
[14]NURUZZAMAN M,MANIMEKALAI R,SHARONI A M,et al.Genome-wide analysis of NAC transcription factor family in rice[J].Gene,2010,465(1--2):30-44.
[15]HU R B,QI G A,KONG Y Z,et al.Comprehensive analysis of NAC domain transcription factor gene family in Populus trichocarpa[J].Bmc Plant Biology,2010,10(1):145.
[16]TRAN L S P,NAKASHIMA K,SAKUMA Y,et al.Isolation and functional analysis of Arabidopsis stress-inducible NAC transcription factors that bind to a drought-responsive cis-element in the early responsive to dehydration stress 1 promoter[J].Plant Cell,2004,16(9):2481-2498.
[17]LU P L,CHEN N Z,AN R,et al.A novel drought-inducible gene,ATAF1,encodes a NAC family protein that negatively regulates the expression of stress-responsive genes in Arabidopsis[J].Plant Molecular Biology,2007,63(2):289-305.
[18]JENSEN M K,LINDEMOSE S,DE MASI F,et al.ATAF1transcription factor directly regulates abscisic acid biosynthetic gene NCED3 in Arabidopsis thaliana[J].Febs Open Bio,2013,3:321-327.
[19]OH S K,LEE S,YU S,et al.Expression of a novel NAC domaincontaining transcription factor(Ca NAC1)is preferentially associated with incompatible interactions between chili pepper and pathogens[J].Planta,2005,222(5):876--887.
[20]DELESSERT C,WILSON I W,VAN DER STRAETEN D,et al.Spatial and temporal analysis of the local response to wounding in Arabidopsis leaves[J].Plant Molecular Biology,2004,55(2):165--181.
[21]DELESSERT C,KAZAN K,WILSON I W,et al.The transcription factor ATAF2 represses the expression of pathogenesisrelated genes in Arabidopsis[J].Plant Journal,2005,43(5):745--757.
[22]WANG X,CULVER J N.DNA binding specificity of ATAF2,a NAC domain transcription factor targeted for degradation by tobacco mosaic virus[J].Bmc Plant Biology,2012,12(1):157.
[23]HUH S U,LEE S B,KIM H H,et al.ATAF2,a NAC transcription factor,binds to the promoter and regulates NIT2 gene expression involved in auxin biosynthesis[J].Molecules and Cells,2012,34(3):305--313.
[24]ZHONG R Q,LEE C H,YE Z H.Functional characterization of poplar wood-associated NAC domain transcription factors[J].Plant Physiology,2010,152(2):1044-1055.
[25]ZHAO Y J,SUN J Y,XU P,et al.Intron-mediated alternative splicing of WOOD-ASSOCIATED NAC TRANSCRIPTION FACTOR1B regulates cell wall thickening during fiber development in Populus species[J].Plant Physiology,2014,164(2):765--776.
[26]GU R S,LIU Q L,PEI D,et al.Understanding saline and osmotic tolerance of Populus euphratica suspended cells[J].Plant Cell Tissue and Organ Culture,2004,78(3):261-265.
[27]LI B S,YIN W L,XIA X L.Identification of microRNAs and their targets from Populus euphratica[J].Biochemical and Biophysical Research Communications,2009,388(2):272--277.
[28]马洪双,夏新莉,尹伟伦.建立胡杨抗逆研究的c DNA-AFLP反应体系[J].北京林业大学学报,2010,32(5):34-40.MA H S,XIA X L,YIN W L.Constructing c DNA-AFLP reaction system of abiotic stress study for Populus euphratica[J].Journal of Beijing Forestry University,2010,32(5):34-40.
[29]段中鑫,覃玉蓉,夏新莉,等.超量表达胡杨peu-MIR156j基因增强拟南芥耐盐性[J].北京林业大学学报,2012,33(6):1--7.DUAN Z X,QIN Y R,XIA X L,et al.Overexpression of Populus euphratica peu-MIR156j gene enhancing salt tolerance in Arabidopsis thaliana[J].Journal of Beijing Forestry University,2012,33(6):1--7.
[30]马洪双,夏新莉,尹伟伦.胡杨SCL7基因及其启动子片段的克隆与分析[J].北京林业大学报,2011,33(1):1--10.MA H S,XIA X L,YIN W L.Cloning and analysis of SCL7 gene from Populus euphratica[J].Journal of Beijing Forestry University,2011,33(1):1--10.
[31]覃玉蓉,夏新莉,尹伟伦.实时荧光定量PCR检测miR169g在脱水与高盐胁迫下胡杨叶中的表达[J].现代仪器,2011,17(3):28--30.QIN Y R,XIA X L,YIN W L.Expression determination of miR169g under dehydration and high salinity stress in Populus euphratica leaves by real-time quantitative PCR[J].Modern Instruments,2011,17(3):28-30.
[32]OHTANI M,NISHIKUBO N,XU B,et al.A NAC domain protein family contributing to the regulation of wood formation in poplar[J].Plant Journal,2011,67(3):499--512.
[33]GOODSTEIN D M,SHU S Q,HOWSON R,et al.Phytozome:a comparative platform for green plant genomics[J].Nucleic Acids Research,2012,40(D1):1178--1186.
[34]SAITOU N,NEI M.The neighbor-joining method:a new method for reconstructing phylogenetic trees[J].Molecular Biology and Evolution,1987,4(4):406--425.
[35]WANG H L,CHEN J H,TIAN Q Q,et al.Identification and validation of reference genes for Populus euphratica gene expression analysis during abiotic stresses by quantitative real-time PCR[J].Physiologia Plantarum,2014,152(3):529--545.
[36]ZHANG X R,HENRIQUES R,LIN S S,et al.Agrobacteriummediated transformation of Arabidopsis thaliana using the floral dip method[J].Nature Protocols,2006,1(2):641--646.
[37]JEONG J S,KIM Y S,BAEK K H,et al.Root-specific expression of Os NAC10 improves drought tolerance and grain yield in rice under field drought conditions[J].Plant Physiology,2010,153(1):185-197.
[38]SONG S Y,CHEN Y,CHEN J,et al.Physiological mechanisms underlying Os NAC5-dependent tolerance of rice plants to abiotic stress[J].Planta,2011,234(2):331-345.
[39]LU M,YING S,ZHANG D F,et al.A maize stress-responsive NAC transcription factor,Zm SNAC1,confers enhanced tolerance to dehydration in transgenic Arabidopsis[J].Plant Cell Reports,2012,31(9):1701-1711.
[40]HU H H,YOU J,FANG Y J,et al.Characterization of transcription factor gene SNAC2 conferring cold and salt tolerance in rice[J].Plant Molecular Biology,2008,67(1-2):169-181.
[41]CHEN S L,LI J K,WANG S S,et al.Effects of Na Cl on shoot growth,transpiration,ion compartmentation,and transport in regenerated plants of Populus euphratica and Populus tomentosa[J].Canadian Journal of Forest Research,2003,33(6):967--975.
[42]OTTOW E A,BRINKER M,TEICHMANN T,et al.Populus euphratica displays apoplastic sodium accumulation,osmotic adjustment by decreases in calcium and soluble carbohydrates,and develops leaf succulence under salt stress[J].Plant Physiology,2005,139(4):1762--1772.
[43]HAN X,TANG S,AN Y,et al.Overexpression of the poplar NFYB7 transcription factor confers drought tolerance and improves water-use efficiency in Arabidopsis[J].Journal of Experimental Botany,2013,64(14):4589-4601.