逆境胁迫对苦荞花期总黄酮含量及关键酶基因表达的影响

为探究花期苦荞在逆境胁迫下的总黄酮含量变化及其响应机理,以川荞3号为材料,研究了盐(Na Cl)、干旱(PEG-6000)及UV-B 3种逆境胁迫对苦荞花期各组织中总黄酮含量的影响,及黄酮合成关键酶基因(CHI、F3H、FLS、FLS1)表达量与花期总黄酮含量之间的关系。结果表明:3种胁迫处理后,根、茎、叶、花中的总黄酮含量均有不同程度的增加。在Na Cl胁迫下,根、茎、叶、花中的总黄酮含量明显增加,且在12 h时叶中达到最高值(160.0 mg·g~(-1));当采用PEG-6000处理后,苦荞的根、茎、叶、花中的总黄酮含量均显著升高,且叶、花对PEG-6000胁迫较其它组织敏感;UV-B胁迫也能显著提高苦荞根、茎、叶中的总黄酮含量,且叶中总黄酮含量变化最大,但花中总黄酮含量却呈极显著下降。Real-time PCR分析表明,在上述逆境胁迫下CHI、F3H、FLS及FLS1基因的m RNA量在茎、叶、花中的变化与总黄酮含量变化趋势相一致,推测这些基因可能在花期苦荞对逆境胁迫的适应中发挥重要作用。本研究结果可为解析苦荞在逆境下的响应机制和通过基因工程培育高黄酮苦荞新品种提供理论依据。     

苦荞细胞色素CYP81家族同源基因FtP450-R4的克隆、分子鉴定及其功能分析

细胞色素P450 (cytochrome P450,CYP450)是高等植物中最大的酶蛋白家族之一,广泛参与植物的次生代谢和抗逆生理.本研究采用同源克隆和cDNA末端快速克隆(rapid-amplification of cDNAends,RACE)技术,获得苦荞(Fagopyrum tataricum) CYP81家族同源基因FtP450-R4 (GenBank登录号:KM271986).FtP450-R4 cDNA全长1770bp,5'-UTR为49 bp,3'-UTR为194bp,ORF为l 527 bp,其ORF序列可编码508个氨基酸残基的蛋白.生物信息学分析表明,FtP450-R4蛋白通过N-端4～24位氨基酸残基定位于内质网,与F3'H (flavonoid 3'-hydroxylase)、I2'H (isoflavone 2'-hydroxylase)和其他CYP450的同源性在44％～46％之间;多重序列比对显示,FtP450-R4具有CYP450中经典的基序和保守序列,但不含F3'H的特征基序(GGEK);系统进化树分析显示,FtP450-R4与拟南芥(Arabidopsis thaliana) CYP81家族和I2'H聚为一大簇,说明其可能参与苦荞黄酮类化合物的羟化或对逆境胁迫的应答.UV-B、寒冷和干旱均能引起FtP450-R4在苦养子叶中表达量的显著变化,而在胚轴中其表达量变化不显著.利用大肠杆菌(Escherchia coli) BL21 (DE3)菌株对FtP450-R4蛋白进行了可溶性表达,活性鉴定表明,重组FtP450-R4蛋白能以还原型烟酰胺腺嘌呤二核苷酸磷酸(reduced form of nicotinamide-adenine dinucleotide phosphate, NADPH)和山奈酚为底物进行酶促反应,具有生物学活性.本研究可为了解CYP450在黄酮合成代谢中的功能,明确苦荞黄酮代谢调控的分子机制提供了基础资料.     

转OsbHLH1和Bar基因水稻及相关特性分析

OsbHLH1基因编码bHLH(basic helix-loop-helix,碱性螺旋-环-螺旋)类转录因子,与水稻耐低温相关。草铵膦是一种高效低毒灭生性除草剂,Bar基因表达产物能解除草铵膦的毒性。本实验对通过农杆菌(Agrobacterium tumefaciens)浸染法获得的以粳型水稻(Oryza sativaL.subsp.japonica Kato)恢复系淮C17为受体的转OsbHLH1和Bar基因水稻进行研究,鉴定其除草剂抗性和耐低温能力,考查其农艺性状。草铵膦筛选发现Bar基因正常表达;对草铵膦筛选获得的转基因植株进行PCR、Southern、RT-PCR和实时荧光定量PCR检测,发现OsbHLH1基因已经整合到水稻基因组中并且在水稻中表达。转基因T3代株系芽期(萌发芽长0.5mm)在2℃条件下处理6d,第6号转基因株系死苗率为17.8%,对照死苗率为61.1%。T3代苗期(一叶一心)在8～10℃下处理7d,第5、6、9、11号株系的根长显著长于对照,第3、5、11号株系的根数显著多于对照,第3号株系的平均鲜重显著重于对照。芽期、苗期耐冷性试验表明,OsbHLH1基因在水稻中过量表达显著提高了水稻芽期、苗期的耐低温能力。对转基因T2代的农艺性状进行考查,株高、千粒重、结实率、理论产量等农艺性状与对照相比较均出现了显著的变化,外源基因的导入对水稻的农艺性状有明显影响。研究结果将为选育抗除草剂、耐低温杂交粳稻新组合提供新种质。     

cDNA微阵列检测水稻幼苗空间特异表达基因*

以含有2200个独立水稻转录本的膜质cDNA微阵列鉴别萌发期水稻(Oryza sativa L.)幼苗的空间特异表达基因。经比较表达谱，得到了在胚芽、胚轴和胚根中特异表达的基因分别为31、36和73个。其中，胚轴特异表达基因包括聚泛蛋白、UDP-葡萄糖焦磷酸酶、蔗糖合酶、磷酸甘油酸激酶等参与糖、蛋白质代谢反应的蛋白，意味着在萌发期水稻幼苗中，胚乳贮藏淀粉和贮藏蛋白的降解反应主要发生在胚轴部。实验检测到的胚芽和胚根特异表达基因包括一些具有防御功能的基因及多个参与复制、转录和翻译过程的基因，如胚芽特异表达的基因中，翻译起始因子5a、40s核糖体蛋白s28及核糖体蛋白136与蛋白合成有关；而过敏性蛋白、β-D-葡聚糖外水解酶和肌动蛋白-11等为抗病相关基因。胚根特异表达的基因中，肽链延伸因子1-α、TATA盒结合蛋白、DNA复制蛋白A2、组蛋白和两种核糖体蛋白等与复制、转录和翻译有关；而富含甘氨酸蛋白、创伤诱导性碱性蛋白、Bowman-Birk蛋白酶抑制因子、脂类转运蛋白-2等基因则与幼苗的防卫反应有关。通过分析这些空间特异表达基因，揭示出一些潜在的生物学规律，为研究萌发生理学提供了有价值的信息。     

内生解淀粉芽胞杆菌β-1,3-1,4-葡聚糖酶基因(bglS)的克隆与表达及酶学特性分析

β-1,3-1,4-内切葡聚糖酶普遍存在于植物内生芽胞杆菌中,为了探讨其功能,以内生解淀粉芽胞杆菌(Bacillus amyloliquefaciens)TB2菌株基因组为模板,克隆了β-1,3-1,4-内切葡聚糖酶基因(bglS).测序结果表明,该基因的ORF全长732 bp,编码一条243个氨基酸的蛋白,理论分子量约为27.33 kD,等电点约为6.89,其ORF序列已登录GenBank(Accession No.EU368224).Blast同源性分析结果表明,该基因的ORF序列与植物互作生防解淀粉芽胞杆菌(B.amyloliquefaciens FZB42,GenBank Accession No.CP000560)的β-1,3-1,4-葡聚糖酶基因核苷酸序列的一致性达97.3%,氨基酸序列的一致性达97.1%.将β-1,3-1,4-内切葡聚糖酶基因全长克隆至pUC18载体上,利用基因自身的启动子构建重组表达载体pUC-bglS,并导入大肠杆菌(Escherichia coli)BL21菌株中表达.SDS-PAGE分析表明,BL21::pUC-bglS菌株表达了27 kD左右的蛋白;该酶的最适反应温度为55℃,在50℃以下保温60 min后残余80%以上酶活;最适反应pH为6.2,在pH4.4～6.8 4℃保温30 min残余85%以上的酶活;Ca2+和Fe肛可提高β-1,3-1,4-葡聚糖酶的活性,而Cu2+、Zn2+、Mg2+和Mn2+对其活性具有显著的抑制作用.实验结果为进一步研究植物内生解淀粉芽胞杆菌TB2 β-1,3-1,4-葡聚糖酶的功能和应用打下了基础.     

稻瘟病菌胁迫下水稻不同单基因系防卫相关基因表达分析

水稻(Oryza sativa)不同稻瘟病抗性基因抗性水平存在显著差异,为了解防卫基因在不同抗性单基因系中的表达模式,本研究利用qRT-PCR方法比较了4个水稻抗稻瘟病单基因系IRB LKh-K3(Pik-h)、IRBLKs-F5 (Pik-s)、IRBLta2-Re (Pita-2)和IRBLta-K1 (Pita)中抗稻瘟病防卫相关基因几丁质酶基因1(chitinase 1,Cht-1)、β-1,3葡聚糖酶基因(β-1,3-glucanase,Glu)、苯丙氨酸解氨酶基因(phenylalanine ammonia lyase,PAL)和过氧化物酶基因(peroxidase,POX22.3)表达的差异.结果表明,在稻瘟病菌(Magnaporthe oryzae)胁迫后的6、12、24、36、48、72和96 h时间点,Cht-1和Glu的表达量在4个单基因系中的差异无明显的规律性.PAL在IRB LKh-K3(Pik-h)基因系中以及POX22.3在IRBLta2-Re (Pita-2)基因系中的表达量均持续高于在其余3个基因系中;前者的最高表达量至少是对照、IRBLta2-Re(Pita-2)、IRBLta-K1(Pita)和IRBLKs-F5(Pik-s)基因系的3.35、3.05、3.85和4.32倍,后者是对照、IRBLta-Kl(Pita)、IRBLKh-K3(Pik-h)和IRBLKs-F5(Pik-s)基因系的24.86、2.12、2.85和2.60倍.研究结果表明,PAL基因与POX22.3基因的表达分别受抗性基因Pik-h和Pita-2的特异调控参与抗性反应,为进一步研究抗性基因的抗性调控机制提供了依据.     

草莓果实中BG基因的克隆及功能分析

脱落酸(abscisic acid,ABA)能促进草莓(Fragaria×ananassa)果实的发育成熟,葡萄糖苷酶(β-glucosidase,BG)能通过水解ABA葡萄糖酯(ABA glucose ester,ABA-GE),把非活性的ABA转换成有活性的ABA,因此,BG参与果实发育进程.但是目前还没有遗传学证据来揭示BG对果实发育的作用机理.为了研究BG在果实发育中的作用,本实验以草莓品种甜查理为试材,通过PCR分子克隆的方法分离到3个编码BG的基因FaBG1、FaBG2和FaBG3;首先对3个基因进行生物信息学、时空表达分析,以及测定果实内源ABA含量的变化;其次通过分子调控FaBG3基因的表达量影响果实内源BG的活性,分析草莓果实的生理指标以及与ABA信号路径、色素代谢和细胞壁代谢相关基因的表达水平.实验结果表明,BG蛋白含有一个BglB区域,是能水解其他的复合物的特异区域.随着草莓果实的发育成熟,ABA的含量逐渐升高,FaBG1基因的表达量一直很低,FaBG2的表达量呈总体的下降趋势,只有FaBG3的表达量与ABA含量变化相一致.利用RNA干扰技术调低草莓果实中FaBG3基因的表达量也下调了FaBG1和FaBG2的表达量,同时降低了果实中BG的活性,导致果实中ABA含量、果实色素和可溶性固形物含量降低,提高了果实的硬度等生理指标,与生理指标相关的如色素代谢基因查尔酮合酶(chalcone synthase, CHS)、查尔酮异构酶(chalcone isomerase,CHI)、类黄酮-3-羟化酶(flavonoid-3-hydroxy-lase,F3H)、类黄酮-3-O-葡萄糖基转移酶(UDP Glc-flavonoid 3-O-glucosyl transferase,UFGT)和二氢黄酮醇-4-还原酶(dihydroflavo-nol-4-reductase,DFR),果实软化基因果胶甲酯酶(pectin methylesterase,PE)、伸展蛋白(expansin,EXP)、多聚半乳糖醛酸酶(polygalacturonase,PG)和果胶酸裂解酶(pectate lyases,PL),果实香味代谢基因醌氧化还原酶(quinone oxidoreductase,QR)、酰基转移酶(alcohol acyltransferase,AT)和ABA信号路径中的基因抗副球菌素蛋白(pyrabatin resistance,PYR)、ABA不敏感体1(ABA insensitive 1,AB11)、ABI3、ABI4和ABI5的表达量等分子指标也出现了不同程度的变化,最后导致了果实延迟成熟.与此相反,FaBG3基因超表达的草莓果实出现了提前着色成熟的现象.果实生理及分子指标的变化可揭示BG调控草莓果实发育进程的机理.     

山羊繁殖季节性相关基因DIO2与DIO3的表达分析

研究表明,2型脱碘酶基因(typeⅡiodothyronine deiodinase gene,DIO2)和3型脱碘酶基因(type Ⅲiodothyronine deiodinase gene,DIO3)对啮齿动物(Rodentia)和绵羊(Ovis aries)的季节性繁殖活动具有重要调控作用.本研究选择常年发情济宁青山羊(Capra hircus)和季节性发情辽宁绒山羊(C.hircus)作为实验对象,应用反转录PCR和定量PCR技术分别对两个基因的组织表达谱及繁殖轴组织中两个基因的表达差异进行检测分析.研究发现,(1)DIO2基因在所研究的24个组织都有一定量表达,DIO3基因主要在小脑、海马、下丘脑、垂体、脑桥以及卵巢和肾上腺等表达,品种间两基因组织表达谱相似;(2)济宁青山羊垂体DIO2基因表达量显著高于辽宁绒山羊(P＜0.05),下丘脑、卵巢表达量也均高于辽宁绒山羊,但两品种间差异不显著(P＞0.05),子宫表达量显著低于辽宁绒山羊(P＜0.05);(3)对于下丘脑组织DIO3基因,则济宁青山羊表达量比辽宁绒山羊明显要高(P＜0.05),而对于卵巢和子宫DIO3基因表达量,则济宁青山羊明显比辽宁绒山羊低(P＜0.05),济宁青山羊垂体DIO3基因表达量低于辽宁绒山羊,但两品种间差异不显著(P＞0.05).本研究提示DIO2和DIO3基因可能与山羊季节性繁殖调控有关,研究结果可为初步揭示山羊繁殖季节性分子调控机制提供参考.     

过量表达盐芥TsIPK2基因增强转基因水稻耐盐性

【目的】本试验以野生型(WT)和转盐芥TsIPK2基因的水稻为材料,研究NaCl胁迫条件下过量表达TsIPK2基因对水稻植株抗盐胁迫能力的影响。【方法】取水稻材料种子和其3叶龄幼苗,分别在不同NaCl浓度(0、50、100、150、200 mmol/L)下进行处理。检测WT与过量表达TsIPK2基因水稻种子的发芽率、主根长和芽长、幼苗的丙二醛(MDA)和脯氨酸的含量,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,以及与胁迫相关的5个基因的表达。【结果】在盐胁迫下,与野生型相比,转基因水稻具有更好的发芽率、主根长和芽长。野生型和转基因水稻两者的脯氨酸含量增加,转基因水稻的积累量显著高于野生型,但是转基因水稻MDA含量增加幅度小于野生型。野生型和转基因水稻幼苗SOD酶活性均增加,但转基因植株的酶活性显著高于野生型;二者POD酶活性呈现先升高后下降的趋势,但是二者活性没有显著的差别;转基因水稻的CAT活性也呈现先升高后下降的趋势,然而野生型水稻的CAT活性在盐胁迫下没有显著的变化。高盐处理后,野生型和转基因水稻的5个与胁迫相关的基因表达倍数都增加,与野生型相比,转基因水稻的OsP5CS1、OsSOD、OsCATB和OsLEA3的表达量显著升高,而OsPOX1基因的表达量变化不显著。【结论】过量表达TsIPK2基因能够通过增强水稻的渗透调节能力、抗氧化胁迫能力并调节胁迫相关基因的表达,以提高水稻的耐盐性。     

桂花15-顺式-ζ-胡萝卜素异构酶基因(Z-ISO)的克隆及表达分析

15-顺式-ζ-胡萝卜素异构酶(15-cis-ζ-carotene isomerase,Z-ISO)可以催化9,15,9'-三顺式-ζ-胡萝卜素异构化生成9,9'-二顺式-ζ-胡萝卜素,Z-ISO基因是植物类胡萝卜素代谢途径中最后一个被鉴定的基因.为克隆桂花(Osmanthus fragrans) Z-ISO基因的ORF序列并研究其表达特征,本研究利用已构建的桂花花瓣转录组数据库中Unigene序列信息,结合PCR技术克隆得到桂花Of Z-ISO1(GenBank登录号:KX120175)和Of Z-ISO2(GenBank登录号:KX120176)基因ORF序列.生物信息学分析表明,Of Z-ISO1和OfZ-ISO2基因均含有长为1 107 bp的ORF,编码368个氨基酸残基.Of Z-ISO1和Of Z-ISO2蛋白均含有6个跨膜螺旋区和3个保守的异构酶功能作用所必需的活性位点(H152、H268和D296).Of Z-ISO1和Of-ISO2与玉米(Zea mays)和拟南芥(Arabidopsis thaliana) Z-ISO1氨基酸序列有较高的相似性,系统进化树分析发现,Of Z-ISO1和Of Z-ISO2与芝麻(Sesamum indicum)Z-ISO亲缘关系最近,聚为同一小支.qRT-PCR结果显示,堰虹桂花序发育过程中,OfZ-ISO1基因在花蕾期花序中表达量较低,铃梗期其表达量急剧增加,初开期表达量保持不变,而盛开期表达量显著下降;Of Z-ISO2基因在花蕾期和铃梗期花序中表达量较低,随后表达量逐渐增加,于盛开期表达量达到最高.在桂花不同花色品种中,丹桂品种堰虹桂花色最深、花瓣类胡萝卜、素总量最高,金桂品种金球桂次之,银桂品种玉玲珑花色最浅、花瓣类胡萝卜素总量最低;总体上铃梗期和初开期时玉玲珑Of Z-ISO1和Of Z-ISO2基因的表达量较高,盛开期3个不同花色品种花瓣中OfZ-ISO1和Ofz-ISO2基因的表达量大致相同.本研究结果表明,桂花花序开放过程中Of Z-ISO1和Of Z-ISO2基因的表达水平对其类胡萝卜素的积累十分重要,不同花色品种类胡萝卜素含量与其Of-ISO1和OfZ-ISO2基因表达量并非正相关.研究结果将为全面揭示桂花呈色机制提供理论基础.     

Factors influencing diamine oxidase activity and γ-aminobutyric acid content of fava bean (Vicia faba L.) during germination

Factors (germination time, spectra, temperature, pH, and chemical inhibitors) influencing diamine oxidase (DAO, EC 1.4.3.6) activity and γ-aminobutyric acid (GABA) content of fava bean (Vicia faba L.) during germination were investigated in this study. DAO activity significantly increased in germinating seeds but varied with different organs. The enzyme activity was higher in shoot than that in cotyledon, hypocotyl, and radicle. When seeds were germinated in the dark, DAO activity was 2.35-, 2.00-, 2.36-, 4.40-, and 1.67-fold of that under white, red, blue, green, and yellow spectra, respectively. The optimum germination temperature and pH value for increasing DAO activity were 30 °C and 3.0, respectively. The DAO activity was inhibited significantly by aminoguanidine and sodium ethylenediamine tetracetate, while it was activated by CuCl(2) and CaCl(2). Germinating at an appropriate temperature and pH, 30% of GABA formation was supplied by DAO. Calcium was related to the regulation of DAO activity and GABA accumulation.     

Cloning, characterization, and activity analysis of a flavonol synthase gene FtFLS1 and its association with flavonoid content in tartary buckwheat

Evidence from in vitro and in vivo studies indicates that rutin, the main flavonoid in tartary buckwheat ( Fagopyrum tataricum ), may have high value for medicine and health. This paper reports the finding of a flavonol synthase (FLS) gene, cloned and characterized from F. tataricum and designated FtFLS1, that is involved in rutin biosynthesis. The FtFLS1 gene was expressed in Escherichia coli BL21(DE3), and the recombinant soluble FtFLS1 protein had a relative molecular mass of 40 kDa. The purified recombinant protein showed, with dihydroquercetin as substrate, total and specific activities of 36.55 × 10(-3) IU and 18.94 × 10(-3) IU/mg, respectively, whereas the total and specific activities were 10.19 × 10(-3) IU and 5.28 × 10(-3) IU/mg, respectively, with dihydrokaempferol. RT-PCR revealed that during F. tataricum florescence there was an organ-specific expression pattern by the FtFLS1 gene, with similar trends in flavonoid content. These observations suggest that FtFLS1 in F. tataricum encodes a functional protein, which might play a key role in rutin biosynthesis.     

Influence of cultivar and germination on bioactive amines in soybeans (Glycine max L. Merril)

The levels of amines in soybeans as affected by cultivar in two consecutive years and by germination were investigated. Spermidine, spermine, putrescine, agmatine, and cadaverine were detected, whereas tyramine, histamine, tryptamine, serotonine, and phenylethylamine were not. Spermidine was the predominant amine followed by spermine. High concentrations of these amines confirmed soybean as a rich source. Cadaverine was confirmed to be inherent to soybean. The percent contribution of spermidine and spermine to total levels was not affected by cultivar in either years. However, amine levels were affected by cultivars in different ways in the consecutive years. Cadaverine was affected more by the cultivar, whereas spermidine, spermine, and agmatine were affected by harvest year. During germination the levels of amines from soybean increased significantly, except for agmatine. Spermidine and spermine accumulated in the cotyledon, whereas cadaverine and putrescine accumulated in the radicle and hypocotyl.     

广西平果县岩溶山地不同植物群落的土壤酶活性

为探讨平果县岩溶山地典型植物群落的土壤酶活性特征,基于调查取样与试验分析,采用相关分析、多重比较以及主成分分析方法,研究了不同植物群落间土壤酶活性的差异,分析了土壤酶活性与土壤化学性质的关系。结果表明:(1)土壤过氧化氢酶、脲酶及蔗糖酶活性的群落间差异达显著水平,显示不同植物群落对土壤酶活性产生一定影响;(2)土壤pH值与过氧化氢酶、脲酶间呈极显著正相关(p0.01),与碱性磷酸酶间呈显著负相关(p0.05);(3)4个酶活性与代表土壤肥力的土壤有机质、全氮、全磷、全钾、碱解氮及速效钾之间具有较强的相关性,但速效磷与4个土壤酶之间的相关性均未达显著水平(p0.05);(4)过氧化氢酶、脲酶及碱性磷酸酶能敏感反映土壤质量的变化,可作为本区域土壤质量评价的指标。     

2JC-500型自动嫁接机西瓜苗嫁接效果生产试验

为了解2JC-500型自动嫁接机嫁接西瓜苗的生产效果及其影响因素,进行了西瓜机械嫁接育苗的生产试验,并测定了嫁接用苗形态对嫁接机嫁接效果的影响。试验结果表明,砧木瓠瓜苗子叶展开角小于45°、接穗西瓜苗胚轴弯曲和子叶不对称于胚轴的情况会分别显著地影响砧木机械打孔和砧穗对接的作业质量;当砧木子叶展开角大于45°,接穗西瓜苗胚轴不弯曲且子叶对称于胚轴时,机械嫁接育苗生产中嫁接机的嫁接成功率可大于90%,2JC-500型嫁接机作业生产率可达450株/h。     

不同成熟度油橄榄果实表观与内在品质变化及相关性分析

为了明确不同成熟度油橄榄果实表观性状与内在品质的变化规律和相关性,以豆果、皮瓜尔、鄂植8号、莱星6个成熟度的果实为试验材料,对果实大小、颜色等8个表观指标以及含油率、脂肪酸组分、还原糖、总酚、总黄酮含量等内在品质指标进行测定,并对各指标间进行相关性分析。结果表明,4个品种油橄榄果实各指标随着成熟度的增加,呈现一定的变化规律,其中随着成熟度的增加,亮度值(L^*值)、红绿值(a^*值)、黄蓝值(b^*值)均先增大后减小,横径增大,纵径变化不显著,横径增长速度大于纵径,果形指数变小,含油率升高,表明果实外观逐渐变圆;还原糖含量先降低后升高,总酚、总黄酮含量在第Ⅰ成熟度时显著高于其他5个成熟度,豆果、皮瓜尔、鄂植8号的饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)与多不饱和脂肪酸(PUFA)比值越来越接近1∶1∶1。不同成熟度油橄榄的含油率与脂肪酸比值、还原糖、总酚含量、果形指数以及果实横径存在相关关系,且与a^*值、总黄酮含量呈极显著相关,相关系数最高分别为0.73、-0.84;a^*值与还原糖含量呈显著负相关,与总酚、总黄酮含量极显著负相关;总黄酮含量与SFA、PUFA呈显著负相关,与总酚含量、MUFA、还原糖含量、果形指数、L^*值、b^*值呈显著正相关。综合变化规律和相关性分析结果认为,油橄榄果实a^*值和总黄酮含量可以代表大部分指标用于进行果实品质检测。本研究结果可为后续机械采收识别系统采集指标数据提供理论依据。     

扁蓿豆水浸提液对其种子萌发自毒作用研究

为了明确扁蓿豆是否存在自毒效应，以期为扁蓿豆科学种植提供理论依据。以扁蓿豆种子为受体，采用室内培养皿种子萌发方法，研究了不同质量浓度(0、0.001、0.025、0.050、0.100 g/mL)扁蓿豆(Medicago ruthenica)地上部分和地下部分水浸提液的自毒作用。结果表明，扁蓿豆植株地上部分与根部水浸提液对其种子发芽率、发芽势、发芽指数、胚根长、胚芽长和单株鲜质量具有一定的抑制作用，总体表现为在质量浓度0.100g/mL下抑制作用最强。扁蓿豆地上部分水浸提液处理在0.100 g/mL质量浓度下发芽率较对照蒸馏水显著降低了39.00%(P < 0.05)，种子发芽指数较对照蒸馏水降低了82.00%；根部水浸提液在0.100 g/mL质量浓度下胚根长较对照蒸馏水显著降低了50.00%。各指标的化感效应指数与质量浓度均呈负相关。     

Antioxidant activity associated with lipid and phenolic mobilization during seed germination of Pangium edule Reinw.

Seeds of the tropical tree Pangium edule Reinw. are widely eaten in Southeast Asia after some treatment or processing. Fermented seeds are a specialty in Indonesia and have been used as spices. Because the tree is wild and has not been cultivated commercially, the physiology of germinated seeds of this tree for food uses is not known. This study reports some biochemical changes during seed germination associated with antioxidant activity and the mobilization of lipids and phenolics. Lipid content decreased, whereas the dominant fatty acids did not change significantly. The dominant fatty acids were oleic acid (C(18:1(n-9))) and linoleic acid (C(18:2(n-6))). During germination, oleic acid decreased while linoleic acid increased proportionally. The hypocotyl synthesized chlorophyll and the tocol composition also changed substantially. The antioxidant activity of phenolic extract increased in proportion to the total phenolics. Guaiacol peroxidase and glucose-6-phosphate dehydrogenase, selected enzymes association with phenolic metabolism, showed that the increased activities coincided with increased total phenolics and free proline.     

Multivariate effects of plant canopy, soil physico-chemistry and microbiology on Sclerotinia stem rot of soybean in relation to crop rotation and urban compost amendment

The effects of canopy, soil physico-chemical and microbiological variables on Sclerotinia stem rot (SSR) on soybean were assessed in two soils (clay loam and sandy loam) using multiple regression and canonical redundancy analysis (RDA) and their partial form to control for the rotation (2 or 3-y-corn/soybean monoculture) and fertilization (mineral/urban compost) or spatial variables effects. The models revealed the minimal sets of variables that best explain the variance of the survival of Sclerotinia sclerotiorum’s sclerotia, carpogenic germination, disease severity and their associations. In clay loam, the 3-y-corn rotation reduced disease severity mainly through the reduction of weed biomass that favoured carpogenic germination. Urban compost has a conducive effect explained by a better soil surface drainage. Additionally, total N was found suppressive to sclerotial survival. In sandy loam, the carpogenic germination was negatively correlated with high C mineralization quotient and aggregate stability but correlated positively with Ca. Sclerotial survival was negatively correlated with pH and Ca, and positively correlated with biological fertility index. Aggregate stability, Ca and pH were associated with the urban compost. The regression and RDA analyses allowed to identify key variables that drived SSR development and explain their relationship with the cultural practices, soil health, as well as the spatial variation of disease variables.