甘蓝型油菜的BR响应及BnBZL2基因的功能分析
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摘要
对甘蓝型油菜(Brassica napus L.)与拟南芥(Arabidopsis thaliana L.)中保守的油菜素甾醇(Brassinosteroids,BR)信号相关基因进行对比分析,并以甘蓝型油菜品种‘沪油15’为材料,对BR信号通路相关同源基因进行了组织表达分析。结果显示,BR合成基因与信号组分在花和幼嫩种子中表达量更高;低浓度BR处理可以促进幼苗根的生长,高浓度BR处理则起抑制作用; BR合成抑制剂(Brassinozole,BRZ)处理可抑制黑暗条件下幼苗下胚轴的伸长; BR处理可以降低BR合成基因的表达水平,而BRZ处理则相反,表明甘蓝型油菜中BR信号增加能反馈抑制BR的合成。烟草(Nicotiana tabacum L.)瞬时表达实验结果发现,与拟南芥BZR1基因同源的甘蓝型油菜BnBZL2编码蛋白定位在细胞质和细胞核中,BR处理可增加BnBZL2的核定位。蛋白质免疫印迹检测结果显示,BR处理可增加去磷酸化BnBZL2的比例。本研究进一步模拟了拟南芥bzr1-1D功能获得性突变体对BnBZL2蛋白进行点突变(BnBZL2*),并构建载体转化拟南芥,黑暗条件下转基因植株幼苗对BRZ处理不敏感,提示BnBZL2*可提高转基因植株的BR信号水平。本研究结果表明甘蓝型油菜中存在与拟南芥相似且保守的BR信号通路和调控机制。
Brassinosteroids( BR) are important phytohormones that regulate plant growth,development,and seed yield. Brassica napus L. is one of the main eatable oil crops in China.Studying BR signaling and regulation of B. napus growth and development can provide clues to increase yield. We compared BR-related genes in B. napus and A. thaliana and analyzed their expression levels in different tissues( using 'Huyou15'as material). Results indicated that the key genes involved in BR synthesis and signal transduction pathways were highly expressed in the flower and young seed; seedling root growth was promoted under BR treatment at low concentration but was inhibited at high concentration; and hypocotyl elongation was inhibited under brassinozole( BRZ,a BR biosynthesis inhibitor) treatment indarkness. Furthermore,BR treatment reduced the expression levels of BR synthesis genes,whereas BRZ treatment increased their expression levels, suggesting that BR signaling feedback inhibited the expression of BR biosynthesis genes. Transient expression experiments in tobacco demonstrated that BnBZL2( BZR1-like gene in B. napus) was localized in the cytoplasm and nucleus,and BR treatment increased the nuclear localization of BnBZL2.Western blotting revealed that BR treatment increased the ratio of dephosphorylated and phosphorylated BnBZL2. The vector of BnBZL2 with point mutations( BnBZL2*,mimicking A.thaliana gain-of-function mutant bzr1-1 D) was transformed into A. thaliana and the transgenic plants showed insensitivity to BRZ treatment in darkness,suggesting that BnBZL2*increased BR signaling. Thus,the above results indicated that BR signaling and regulatory mechanisms were conserved in B. napus and A. thaliana.
Brassinosteroids( BR) are important phytohormones that regulate plant growth,development,and seed yield. Brassica napus L. is one of the main eatable oil crops in China.Studying BR signaling and regulation of B. napus growth and development can provide clues to increase yield. We compared BR-related genes in B. napus and A. thaliana and analyzed their expression levels in different tissues( using 'Huyou15'as material). Results indicated that the key genes involved in BR synthesis and signal transduction pathways were highly expressed in the flower and young seed; seedling root growth was promoted under BR treatment at low concentration but was inhibited at high concentration; and hypocotyl elongation was inhibited under brassinozole( BRZ,a BR biosynthesis inhibitor) treatment indarkness. Furthermore,BR treatment reduced the expression levels of BR synthesis genes,whereas BRZ treatment increased their expression levels, suggesting that BR signaling feedback inhibited the expression of BR biosynthesis genes. Transient expression experiments in tobacco demonstrated that BnBZL2( BZR1-like gene in B. napus) was localized in the cytoplasm and nucleus,and BR treatment increased the nuclear localization of BnBZL2.Western blotting revealed that BR treatment increased the ratio of dephosphorylated and phosphorylated BnBZL2. The vector of BnBZL2 with point mutations( BnBZL2*,mimicking A.thaliana gain-of-function mutant bzr1-1 D) was transformed into A. thaliana and the transgenic plants showed insensitivity to BRZ treatment in darkness,suggesting that BnBZL2*increased BR signaling. Thus,the above results indicated that BR signaling and regulatory mechanisms were conserved in B. napus and A. thaliana.
引文
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[22]Yang BJ,Lin WH,Fu FF,Xu ZH,Xue HW.Receptor-like protein ELT1 promotes brassinosteroid signaling through interacting with and suppressing the endocytosis-mediated degradation of receptor BRI1[J].Cell Res,2017,27(9):1182-1185.
[23]朱聪明.油菜素甾醇类及茉莉酸类化合物对油菜籽粒产量及品质的调节作用[D].武汉:华中农业大学,2013.
[24]Dhaubhadel S,Chaudhary S,Dobinson KF,Krishna P.Treatment with 24-epibrassinolide,a brassinosteroid,increases the basic thermotolerance of Brassica napus and tomato seedlings[J].Plant Mol Biol,1999,40(2):333-342.
[25]Derevyanchuk M,Kretynin S,Iakovenko O,Litvinovskaya R,Zhabinskii V,et al.Effect of 24-epibrassinolide on Brassica napus alternative respiratory pathway,guard cells movements and phospholipid signaling under salt stress[J].Steroids,2017,117:16-24.
[26]Sahni S,Prasad BD,Liu Q,Grbic V,Sharpe A,et al.Overexpression of the brassinosteroid biosynthetic gene DWF4 in Brassica napus simultaneously increases seed yield and stress tolerance[J].Sci Rep,2016,6:28298.
[27]Chory J,Nagpal P,Peto CA.Phenotypic and genetic analysis of det2,a new mutant that affects light-regulated seedling development in Arabidopsis[J].Plant Cell,1991,3(5):445-459.
[28]Nagata N,Min YK,Nakano T,Asami T,Yoshida S.Treatment of dark-grown Arabidopsis thaliana with a brassinosteroid-biosynthesis inhibitor,brassinazole,induces some characteristics of light-grown plants[J].Planta,2000,211(6):781.
[29]Wang ZY,Nakano T,Gendron J,He J,Chen M,et al.Nuclear-localized BZR1 mediates brassinosteroid-induced growth and feedback suppression of brassinosteroid biosynthesis[J].Dev Cell,2002,2(4):505-513.
[30]Shimada Y,Goda H,Nakamura A,Takatsuto S,Fujioka S,Yoshida S.Organ-specific expression of brassinosteroid-biosynthetic genes and distribution of endogenous brassinosteroids in Arabidopsis[J].Plant Physiol,2003,131(1):287-297.
[31]Choe S,Fujioka S,Noguchi T,Takatsuto S,Yoshida S,Feldmann KA.Over-expression of DWARF4 in brassinosteroid biosynthetic pathway results in increased vegetative growth and seed yield in Arabidopsis[J].Plant J,2001,26(6):573-582.
[32]Manoli A,Trevisan S,Quaggiotti S,Varotto S.Identification and characterization of the BZR transcription factor family and its expression in response to abiotic stresses in Zea mays L.[J].Plant Growth Regul,2018,84(3):423-436.
[33]Saha G,Park JI,Jung HJ,Ahmed NU,Kayum MA,et al.Molecular characterization of BZR transcription factor family and abiotic stress induced expression profiling in Brassica rapa[J].Plant Physiol Biochem,2015,92:92-104.
[2]Belkhadir Y,Jaillais Y.The molecular circuitry of brassinosteroid signaling[J].New Phytol,2015,206(2):522-540.
[3]Sasse JM.Physiological actions of Brassinosteroids:an update[J].J Plant Growth Regul,2003,22(4):276-288.
[4]Clouse SD.Brassinosteroid signal transduction:from receptor kinase activation to transcriptional networks regulating plant development[J].Plant Cell,2011,23(4):1219-1230.
[5]Huang HY,Jiang WB,Hu YW,Wu P,Zhu JY,et al.BRsignal influences Arabidopsis ovule and seed number through regulating related genes expression by BZR1[J].Mol Plant,2013,6(2):456-469.
[6]Jiang WB,Huang HY,Hu YW,Zhu SW,Wang ZY,Lin WH.Brassinosteroid regulates seed size and shape in Arabidopsis[J].Plant Physiol,2013,162(4):1965-1977.
[7]Li J,Nagpal P,Vitart V,McMorris TC,Chory J.A role for brassinosteroids in light-dependent development of Arabidopsis[J].Science,1996,272(5260):398-401.
[8]Ohnishi T,Godza B,Watanabe B,Fujioka S,Hategan L,et al.CYP90A1/CPD,a brassinosteroid biosynthetic cytochrome P450 of Arabidopsis,catalyzes C-3 oxidation[J].J Biol Chem,2012,287(37):31551-31560.
[9]Choi YH,Fujioka S,Harada A,Yokota T,Takatsuto S,Sakurai A.A brassinolide biosynthetic pathway via 6-deoxocastasterone[J].Phytochemistry,1996,43(3):593-596.
[10]Asami T,Yoshida S.Characterization of brassinazole,a triazole-type brassinosteroid biosynthesis inhibitor[J].Plant Physiol,2000,123(1):93.
[11]孙超,黎家.油菜素甾醇类激素的生物合成、代谢及信号转导[J].植物生理学报,2017,53(3):291-307.Sun C,Li J.Biosynthesis,metabolism and signal transduction of brassinosteroids[J].Journal of Plant Physiology,2017,53(3):291-307.
[12]Wang ZY,Bai MY,Oh E,Zhu JY.Brassinosteroid signaling network and regulation of photomorphogenesis[J].Annu Rev Genet,2012,46:701-724.
[13]Li J,Wen J,Lease KA,Doke JT,Tax FE,Walker JC.BAK1,an Arabidopsis LRR receptor-like protein kinase,interacts with BRI1 and modulates brassinosteroid signaling[J].Cell,2002,110(2):213-222.
[14]Kim TW,Guan S,Sun Y,Deng Z,Tang W,et al.Brassinosteroid signal transduction from cell-surface receptor kinases to nuclear transcription factors[J].Nat Cell Biol,2009,11(10):1254-1260.
[15]Kim TW,Guan S,Burlingame AL,Wang ZY.The CDG1kinase mediates brassinosteroid signal transduction from BRI1 receptor kinase to BSU1 phosphatase and GSK3-like kinase BIN2[J].Mol Cell,2011,43(4):561-571.
[16]He JX,Gendron JM,Yang Y,Li J,Wang ZY.The GSK3-like kinase BIN2 phosphorylates and destabilizes BZR1,a positive regulator of the brassinosteroid signaling pathway in Arabidopsis[J].Proc Natl Acad Sci USA,2002,99(15):10185-10190.
[17]Yin Y,Wang ZY,Mora-Garcia S,Li J,Yoshida S,et al.BES1 accumulates in the nucleus in response to brassinosteroids to regulate gene expression and promote stem elongation[J].Cell,2002,109(2):181-191.
[18]Yamamuro C,Ihara Y,Wu X,Noguchi T,Fujioka S,et al.Loss of function of a rice brassinosteroid insensitive1homolog prevents internode elongation and bending of the lamina joint[J].Plant Cell,2000,12(9):1591-1606.
[19]Bai MY,Zhang LY,Gampala SS,Zhu SW,Song WY,et al.Functions of OsBZR1 and 14-3-3 proteins in brassinosteroid signaling in rice[J].Proc Natl Acad Sci USA,2007,104(34):13839-13844.
[20]Tong H,Chu C.Brassinosteroid signaling and application in rice[J].J Genet Genomics,2012,39(1):3-9.
[21]Zhang Y,Zhang YJ,Yang BJ,Yu XX,Wang D,et al.Functional characterization of Gm BZL2(At BZR1 like gene)reveals the conserved BR signaling regulation in Glycine max[J].Sci Rep,2016,6:31134.
[22]Yang BJ,Lin WH,Fu FF,Xu ZH,Xue HW.Receptor-like protein ELT1 promotes brassinosteroid signaling through interacting with and suppressing the endocytosis-mediated degradation of receptor BRI1[J].Cell Res,2017,27(9):1182-1185.
[23]朱聪明.油菜素甾醇类及茉莉酸类化合物对油菜籽粒产量及品质的调节作用[D].武汉:华中农业大学,2013.
[24]Dhaubhadel S,Chaudhary S,Dobinson KF,Krishna P.Treatment with 24-epibrassinolide,a brassinosteroid,increases the basic thermotolerance of Brassica napus and tomato seedlings[J].Plant Mol Biol,1999,40(2):333-342.
[25]Derevyanchuk M,Kretynin S,Iakovenko O,Litvinovskaya R,Zhabinskii V,et al.Effect of 24-epibrassinolide on Brassica napus alternative respiratory pathway,guard cells movements and phospholipid signaling under salt stress[J].Steroids,2017,117:16-24.
[26]Sahni S,Prasad BD,Liu Q,Grbic V,Sharpe A,et al.Overexpression of the brassinosteroid biosynthetic gene DWF4 in Brassica napus simultaneously increases seed yield and stress tolerance[J].Sci Rep,2016,6:28298.
[27]Chory J,Nagpal P,Peto CA.Phenotypic and genetic analysis of det2,a new mutant that affects light-regulated seedling development in Arabidopsis[J].Plant Cell,1991,3(5):445-459.
[28]Nagata N,Min YK,Nakano T,Asami T,Yoshida S.Treatment of dark-grown Arabidopsis thaliana with a brassinosteroid-biosynthesis inhibitor,brassinazole,induces some characteristics of light-grown plants[J].Planta,2000,211(6):781.
[29]Wang ZY,Nakano T,Gendron J,He J,Chen M,et al.Nuclear-localized BZR1 mediates brassinosteroid-induced growth and feedback suppression of brassinosteroid biosynthesis[J].Dev Cell,2002,2(4):505-513.
[30]Shimada Y,Goda H,Nakamura A,Takatsuto S,Fujioka S,Yoshida S.Organ-specific expression of brassinosteroid-biosynthetic genes and distribution of endogenous brassinosteroids in Arabidopsis[J].Plant Physiol,2003,131(1):287-297.
[31]Choe S,Fujioka S,Noguchi T,Takatsuto S,Yoshida S,Feldmann KA.Over-expression of DWARF4 in brassinosteroid biosynthetic pathway results in increased vegetative growth and seed yield in Arabidopsis[J].Plant J,2001,26(6):573-582.
[32]Manoli A,Trevisan S,Quaggiotti S,Varotto S.Identification and characterization of the BZR transcription factor family and its expression in response to abiotic stresses in Zea mays L.[J].Plant Growth Regul,2018,84(3):423-436.
[33]Saha G,Park JI,Jung HJ,Ahmed NU,Kayum MA,et al.Molecular characterization of BZR transcription factor family and abiotic stress induced expression profiling in Brassica rapa[J].Plant Physiol Biochem,2015,92:92-104.