大豆籽粒发育过程中异黄酮合成相关酶基因的表达模式与异黄酮积累的相关分析

利用高效液相色谱法和实时定量PCR方法,分别测定了2个异黄酮含量显著差异的大豆品种鲁黑豆2号(LHD2)和南汇早黑豆(NHZ)在子粒发育过程中的异黄酮含量变化以及异黄酮合成相关酶基因的表达模式变化,试图分析异黄酮积累与各基因表达量变化的相关关系。结果表明在大豆子粒发育过程中,异黄酮含量逐渐升高,而不同异黄酮合成相关酶基因的表达趋势不同,CHS7、CHS8、CHR、CHI1A和IFS2的表达趋势与异黄酮积累模式基本一致,而IFS1和CHI1B1的表达趋势与异黄酮积累模式相反。IFR的表达模式在2个大豆品种中存在相反的趋势,在LHD2中与异黄酮组分积累趋势相反,而在NHZ中与异黄酮组分积累趋势相同。结果还表明,同一基因家族中不同基因在子粒发育过程中的表达量也存在差异。查尔酮合酶基因家族中CHS7和CHS8以及查尔酮异构酶基因家族的CHI1A的表达水平相对其他成员较高,异黄酮合酶基因家族中IFS2的表达量显著高于IFS1的表达量,预示这些基因家族在大豆子粒异黄酮积累过程中存在功能分化。此外,各基因表达模式与异黄酮积累的相关分析结果表明,不同基因表达模式与异黄酮积累的相关性在2个品种中也不尽相同。LHD2中CHS7、CHS8和IFS2在子粒发育过程中的表达量变化与不同异黄酮组分呈显著正相关,CHI1B1基因的表达量变化与不同异黄酮组分呈显著负相关。而在NHZ中,IFR在子粒发育过程中的表达量变化与多个异黄酮组分呈显著正相关。这预示了不同大豆品种异黄酮含量差异的潜在遗传基础。各异黄酮合成相关酶基因表达量变化的相关分析表明,在2个品种中,苯丙氨酸水解酶PAL1与4CL,4CL与CHS2以及CHS1与IFS2基因的表达量均呈现显著正相关。表明这些基因可能通过协同作用共同调控异黄酮的合成与积累。这些结果为今后利用基因工程提高大豆异黄酮含量奠定了基础。     

荫蔽信号对大豆幼苗异黄酮合成的影响

荫蔽导致植物所受红光/远红光(R/FR)比值下降,为探究荫蔽对大豆幼苗异黄酮合成的影响,本试验以耐荫性差异显著的大豆品种"ND12"和"C103"幼苗为研究材料,分别施以不同比例红光/远红光(R/FR)处理,对其叶片、下胚轴、根系中异黄酮积累量及关键酶基因表达情况进行比较研究。结果表明,低R/FR条件下,强耐荫品种"ND12"叶片中总异黄酮及染料木素GE的含量极显著上升,下胚轴中极显著下降,弱耐荫品种"C103"则相反。同时,低R/FR使强耐荫品种"ND12"叶片中异黄酮合成关键基因IFS2、4CL、C4H和CHI的表达量极显著上调,其变化趋势与异黄酮积累变化规律一致,而弱耐荫性品种"C103"则存在较大差异。荫蔽信号诱导耐荫型大豆品种异黄酮合成,并在受胁迫部位叶片中大量积累。本研究初步揭示了荫蔽信号(低R/FR)对苗期大豆异黄酮的调控规律,为研究大豆异黄酮响应荫蔽信号的调控机理奠定了基础。     

干旱胁迫对苗期大豆异黄酮合成的影响

以不同耐旱性的2个大豆品种(高耐旱JP-6、低耐旱JP-16)为研究材料,采用高效液相色谱和实时荧光定量PCR技术,分析不同时间持续干旱胁迫下,大豆叶片和根系中异黄酮的积累变化及关键酶基因的表达情况.结果表明:大豆根部异黄酮含量显著高于叶部,而异黄酮关键酶基因的表达量则在叶片中更高,耐旱品种JP-6根部的异黄酮积累量更大.随着干旱胁迫持续时间的增加,不同耐旱品种的异黄酮合成与积累变化规律存在显著差异:强耐旱品种JP-6的根和叶中,异黄酮积累量均呈现先下降后升高的趋势;而弱耐旱品种JP-16则相反,异黄酮积累量在不同部位中均呈现先上升后降低的趋势;除JP-6叶中C4H、4CL、IFS2等异黄酮合成上游基因外,其他不同品种、不同部位的关键酶基因表达量均随着干旱胁迫持续时间的增加,呈现先下降后上升的趋势.大豆叶片是异黄酮的主要合成部位,大豆根部也存在少量的异黄酮合成.弱耐旱大豆根部的异黄酮合成和最终积累量均较低,强耐旱品种则较高.根部异黄酮积累量高的大豆品种,其耐旱性更强.     

crylA基因在转基因玉米中的遗传与表达

通过Southern杂交、ELISA分析等方法,研究了crylA基因在转基因玉米中的遗传与表达。结果表明,crylA基因在转基因玉米中呈单位点显性基因遗传。crylA杀虫基因在转基因玉米不同株系中的表达量存在显著差异;在转基因玉米同一植株不同组织中的表达量也明显不同,在叶片,苞叶等绿色组织中的表达量显著高于在髓、花粉等非绿色组织中的表达量;在玉米叶片中的表达量随着发育期的推进有上升的趋势,在研究的3个转基因工程株系中,crylA杀虫蛋白的表达量在R2、R3、R4代之间无显著差异。     

cry1A基因在转基因玉米中的遗传与表达(英文)

通过Southern杂交、ELISA分析等方法 ,研究了cry1A基因在转基因玉米中的遗传与表达。结果表明 ,cry1A基因在转基因玉米中呈单位点显性基因遗传。cry1A杀虫蛋白在转基因玉米不同株系中的表达量存在显著差异 ;在转基因玉米同一植株不同组织中的表达量也明显不同 ,在叶片、苞叶等绿色组织中的表达量显著高于在髓、花丝等非绿色组织中的表达量 ;在玉米叶片中的表达量随着发育期的推进有上升的趋势 ;在研究的 3个转基因玉米株系中 ,cry1A杀虫蛋白的表达量在R2 、R3 、R4代之间无显著差异。     

cry1A基因在转基因玉米中的遗传与表达

通过Southern杂交、ELISA分析等方法, 研究了cry1A基因在转基因玉米中的遗传与表达.结果表明,cry1A基因在转基因玉米中呈单位点显性基因遗传.cry1A杀虫蛋白在转基因玉米不同株系中的表达量存在显著差异;在转基因玉米同一植株不同组织中的表达量也明显不同,在叶片、苞叶等绿色组织中的表达量显著高于在髓、花丝等非绿色组织中的表达量;在玉米叶片中的表达量随着发育期的推进有上升的趋势;在研究的3个转基因玉米株系中,cry1A杀虫蛋白的表达量在R2、R3、R4代之间无显著差异.     

普通小麦中Puroindo1ine b-2基因的分子鉴定及表达分析

Puroindoline b-2基因与小麦子粒硬度及其产量密切相关。本研究采用特异引物PCR扩增,荧光定量PCR(RTPCR)方法以及DNA测序技术,对81份国内外小麦品种(系)的Puroindoline b-2不同变异类型进行了分子鉴定,并对Puroindoline b-B2的不同变异类型在子粒、叶片以及根系部位中的表达水平进行了定量分析。结果表明,所有试验材料中的D和A基因组上均含有Pinb-D2v1和Pinb-A2v4类型,而B基因组上的Pinb-B2v3类型在所有材料中所占比例最高,为91.4%;Pinb-B2v2类型比例较低,仅为8.6%。不同变异类型间Pinb-B2基因表达量分析表明,小麦子粒中Pinb-B2v3b的表达量显著高于PinbB2v2变异类型。进一步研究表明,Pinb-B2v3b类型的相对表达量显著高于Pinb-B2v3a和Pinb-B2v3c两种类型,而此2种变异之间无明显差异(Pinb-B2v3c略高于Pinb-B2v3a变异)。不同组织间Pinb-B2基因表达量分析表明,小麦叶片中Pinb-B2的表达量显著高于根系中的表达量。本研究为进一步理解Pinb-2基因分子遗传基础提供了一定的理论依据。     

OsPT6基因过表达对低磷条件下菜用大豆结瘤及固氮的影响

采用砂培方法,以转OsPT6基因的菜用大豆(T3株系)与其非转基因(NT)受体品种为实验材料,研究了两者在低磷条件下的生长发育指标,植株有效磷、全磷、全氮、豆血红蛋白和籽粒蛋白质含量以及谷氨酰胺合成酶活性的差异,并对植株结瘤及固氮相关基因表达进行检测,为阐明转OsPT6基因菜用大豆在低磷条件下结瘤及固氮相关机理提供理论依据。结果显示:(1)转基因植株的株高、茎粗、花数和荚数、根瘤数均显著高于NT植株。(2)转基因植株根、茎、叶及根瘤中有效磷,全株总磷、总氮含量,根瘤中的豆血红蛋白含量、功能叶片中谷氨酰胺合成酶的活性和籽粒蛋白质含量均显著高于NT植株。(3)相关性分析表明,豆血红蛋白含量、谷氨酰胺合成酶活性、总磷、总氮含量4个指标间均呈显著正相关关系。(4)GmENOD40a、GmENOD40b、GmGS1β1、GmGS1β2基因在转基因植株中的表达量显著高于NT植株。研究表明,OsPT6基因过表达增强了菜用大豆在低磷条件下的结瘤及固氮能力,该研究结果为进一步研究其调控机理奠定了基础。     

粉葛PtCHI基因的克隆、原核表达和亚细胞定位

为探究葛根品种间异黄酮类物质代谢关键酶基因PtCHI的分子机制差异，并揭示其品种间异黄酮物质含量差异的原因，该研究以野葛品种‘桂葛8号’和粉葛品种‘桂葛1号’为材料，经乙醇提取并通过高效液相色谱仪对野葛和粉葛中葛根素和总黄酮的含量进行测定，基于已报道的野葛CHI基因，通过同源克隆方法分离粉葛中PtCHI基因，并在体外进行蛋白表达，同时在拟南芥原生质体中研究PtCHI基因的定位。结果表明：(1)野葛中的葛根素含量显著高于粉葛的，野葛的总黄酮含量也高于粉葛但未达到显著水平。(2)成功分离到粉葛PtCHI基因，长度为742 bp且包含672 bp完整的ORF框，编码223个氨基酸，与野葛的CHI基因具有99%的同源性。(3)CHI基因在粉葛中的表达量为茎>根>叶子，在野葛中则为根>茎>叶子，除叶子外野葛中CHI基因的表达量均显著高于粉葛。(4)经预测，粉葛PtCHI蛋白为稳定的亲水性蛋白且大小为27.8 kD,二、三级结构以α-螺旋为主，具有25个磷酸化位点，与野葛、大豆和乌拉尔甘草的亲缘关系较近，与F3H2、F3H、4CL4、DFR2及CHS发生互作的可能性较大。(...     

具不同蛋白质含量水稻品种中天冬酰胺合成酶基因的表达

为研究水稻中氮同化与籽粒蛋白质合成可能的关系,本实验通过Northern杂交分析比较了氮同化关键酶一天冬酰胺合成酶基因(OsAS)在不同水稻品种中的表达特性.结果显示,OsAS基因在水稻不同组织及其不同发育时期中的表达水平不同,以发育种子中的表达量最高,叶鞘和叶片中相对较弱;在籽粒发育过程中OsAS基因的表达呈先升高后下降的趋势.具不同种子蛋白质含量水稻品种叶片中OsAS基因的表达水平存在显著差异,相关性分析显示在籼亚种或粳亚种不同品种内OsAS基因表达量与籽粒蛋白质含量可能存在一定的关联.     

Isoflavonoid biosynthesis and accumulation in developing soybean seeds

Isoflavonoids are biologically active natural products that accumulate in soybean seeds during development. The amount of isoflavonoids present in soybean seed is variable, depending on genetic and environmental factors that are not fully understood. Experiments were conducted to determine whether isoflavonoids are synthesized within seed tissues during development, or made in other plant organs and transported to the seeds where they accumulate. An analysis of isoflavonoids by HPLC detected the compounds in all organs of soybean plant, but the amount of isoflavonoids present varied depending on the tissue and developmental stage. The greatest concentrations were found in mature seeds and leaves. The 2-hydroxyisoflavanone synthase genes IFS1 and IFS2 were studied to determine their pattern of expression in different tissues and developmental stages. The highest level of expression of IFS1 was observed in the root and seed coat, while IFS2 was most highly expressed in embryos and pods, and in elicitor-treated or pathogen-challenged tissues. Incorporation of radiolabel into isoflavonoids was observed when developing embryos and other plant organs were fed with [(14)C]phenylalanine. Embryos excised from developing soybean seeds also accumulated isoflavonoids from a synthetic medium. A maternal effect on seed isoflavonoid content was noted in reciprocal crosses between soybean cultivars that differ in seed isoflavonoids. From these results, we propose that developing soybean embryos have an ability to synthesize isoflavonoids de novo, but that transport from maternal tissues may in part contribute to the accumulation of these natural products in the seed.     

大豆转录因子基因GmMYBJ6的表达及功能分析

MYB转录因子是最大的植物转录因子家族之一, 对植物的生长发育及生理代谢具有重要的调节作用。GmMYBJ6 (GenBank登录号: DQ902863)是从大豆中分离克隆的新的MYB转录因子基因, 本文对其在植物中的表达及功能进行了初步研究。利用Norhern杂交对GmMYBJ6在不同组织中的表达情况进行了检测, 结果只在叶片中检测到了GmMYBJ6的表达; 酵母表达结果显示, GmMYBJ6具有明显的转录激活功能, b－半乳糖苷酶活性为28.48 U/mL; 构建绿色荧光蛋白融合表达载体, 基因枪法转化洋葱表皮细胞进行瞬时表达, 结果表明, GmMYBJ6蛋白定位于细胞核中; 半定量RT-PCR检测结果显示, 在转化烟草中, GmMYBJ6的表达可提高类黄酮代谢途径中的苯丙氨酸氨基裂解酶(PAL)、肉桂酸-4-羟化酶(C4H)、4-香豆酰辅酶A连接酶(4CL)、查尔酮合成酶(CHS)、黄酮醇合成酶(FLS)等关键酶的表达, 并且使烟草中总黄酮的含量增加; 此外, 在紫外辐射、高盐及干旱(PEG)等处理下, 大豆品种吉林3号中GmMYBJ6的表达量明显增加, 显示GmMYBJ6对非生物胁迫具有明显的应答反应。     

QTL underlying the resistance to soybean aphid (<Emphasis Type="Italic">Aphis glycines</Emphasis> Matsumura) through isoflavone-mediated antibiosis in soybean cultivar ‘Zhongdou 27’

Soybean aphid (Aphis glycines Matsumura) results in severe yield loss of soybean in many soybean-growing countries of the world. A few loci have been previously identified to be associated with the aphid resistance in soybean. However, none of them was via isoflavone-mediated antibiosis process. The aim of the present study was to conduct genetic analysis of aphid resistance and to identify quantitative trait loci (QTL) underlying aphid resistance in a Chinese soybean cultivar with high isoflavone content. One hundred and thirty F_5:6 derived recombinant inbred lines from the ‘Zhongdou 27’ × ‘Jiunong 20’ cross were used. Two QTL were directly associated with resistance to aphid as measured by aphid damage index. qRa_1, close to Satt470 on soybean linkage group (LG) A2 (chromosome 8), was consistently detected for 3- and 4-week ratings and explained a large portion of phenotypic variations ranging from 25 to 35%. qRa_2, close to Satt144 of LG F (chromosome 13), was detected for 3- and 4-week ratings and could explain 7 and 11% of the phenotypic variation, respectively. These two QTL were highly associated with high isoflavone content and both positive alleles were derived from ‘Zhongdou 27’, a cultivar with higher isoflavone content. The results revealed that higher individual or total isoflavones contents in soybean lines could protect soybean against aphid attack. These two QTL detected jointly provide potential for marker-assisted selection to improve the resistance of soybean cultivars to aphid along with the increase of isoflavone content.     

Polymorphism and expression of isoflavone synthase genes from soybean cultivars

Isoflavones are synthesized by isoflavone synthases via the phenylpropanoid pathway in legumes. We have cloned two isoflavone synthase genes, IFS1 and IFS2, from a total of 18 soybean cultivars. The amino acid residues of the proteins that differed between cultivars were dispersed over the entire coding region. However, amino acid sequence variation did not occur in conserved domains such as the ERR triad region, except that one conserved amino acid was changed in the IFS2 protein of the GS12 cultivar (R374G) and the IFS1 proteins of the 99M06 and Soja99s65 cultivars (A109T, F105I). In three cultivars (99M06, 99M116, and Simheukpi), most of amino acid changes were such that the difference between the amino acid sequences of IFS1 and IFS2 was reduced. The expression profiles of three enzymes that convert naringenin to the isoflavone, genistein, chalcone isomerase (CHI), isoflavone synthase (IFS) and flavanone 3-hydroxylase (F3H) were examined. In general, IFS mRNA was more abundant in etiolated seedlings than mature plants whereas the levels of CHI and F3H mRNAs were similar in the two stages. During seed development, IFS was expressed a little later than CHI and F3H but expression of these three genes was barely detectable, if at all, during later seed hardening. In addition, we found that the levels of CHI, F3H, and IFS mRNAs were under circadian control. We also showed that IFS was induced by wounding and by application of methyl jasmonate to etiolated soybean seedlings.