低温强光下籼粳稻紫黄质脱环氧化酶活性和类囊体膜脂不饱和度的变化

为了阐明籼稻(oryza sativa L.spp.indica)、粳稻(O.sativa L.spp.japonica)对低温强光敏感性的差异,着重研究了低温强光下水稻类囊体膜脂不饱和度与叶黄素循环的变化.随着低温强光处理时间的延长,类囊体膜脂不饱和脂肪酸含量降低,饱和脂肪酸含量增加,因而膜脂不饱和指数(IUFA)下降.同时,叶黄素循环的关键酶--紫黄质脱环氧化酶(VDE)活性降低,叶黄素循环组分中紫黄质(V)含量增加,而单环氧玉米黄质(A)和下米黄质(Z)的含量减少,表现为(A+Z)/(A+Z+V)比值下降.Arrhenius分析证明,VDE对低温和膜脂不饱和度都敏感.相关分析表明,类囊体IUFA分别与VDE活性、(A+Z)/(A +Z+V)和D1蛋白量呈显著的正相关.与粳稻9516相比,籼稻油优63类囊体膜的IUFA较低,低温下类囊体膜脂流动性和稳定性较差,VDE活性和(A+Z)/(A+Z+V)比值较低.     

低温强光下籼粳稻紫黄质脱环氧化酶活性和类囊体膜脂不饱和度的变化

为了阐明籼稻(Oryza sativa L.spp.indica)、粳稻(O.sativa L.spp.japonica)对低温强光敏感件的差异,着重研究了低温强光下水稻类囊体膜脂不饱和度与叶黄素循环的变化。随着低温强光处理时间的延长,类囊体膜脂不饱和脂肪酸含量降低,饱和脂肪酸含量增加,因而膜脂不饱和指数(IUFA)下降。同时,叶黄素循环的关键酶——紫黄质脱环氧化酶(VDE)活性降低,叶黄素循环组分中紫黄质(V)含量增加,而单环氧玉米黄质(A)和玉米黄质(Z)的含量减少,表现为(A Z)／(A Z V)比值下降。Arrhenius分析证明,VDE对低温和膜脂不饱和度都敏感。相关分析表明,类囊体IUFA分别与VDE活性、(A Z)／(A Z V)和D1蛋白量呈显著的正相关。与粳稻9516相比,籼稻汕优63类囊体膜的IUFA较低,低温下类囊体膜脂流动性和稳定性较筹,VDE活性和(A Z)／(A Z V)比值较低。     

紫黄质脱环氧化酶的某些特性和研究方法

紫黄质脱环氧化酶是高等植物体内叶黄素循环的关键酶,它催化紫黄质脱环氧化生成花药黄质和玉米黄质,在这个过程中伴随着过剩光能的热耗散.文中主要对此酶的性质、功能、研究方法以及分子生物学等内容作了简要介绍.     

叶黄素循环酶

依赖叶黄素循环的热耗散是一种主要防御光破坏的机制。参与叶黄素循环的酶是紫黄质脱环氧化酶和玉米黄质环氧化酶 ,紫黄质脱环氧化酶已分离纯化 ,其 c DNA已被克隆 ,其活性主要受跨类囊体膜的 p H梯度和抗坏血酸浓度的调节 ;玉米黄质环氧化酶还没有被分离出来 ,但其 c DNA也已被克隆 ;其活性主要与NADPH的浓度、O2 及光等有关。     

枸杞紫黄质脱环氧化酶(LcVDE)基因的克隆和分析

目的:克隆枸杞VDE基因的全长cDNA,通过对基因序列的生物信息学分析预测表达产物的结构特征和功能位点并验证其功能,为研究枸杞紫黄质循环的作用机理打下基础。方法:利用cDNA末端快速扩增和RT-PCR方法克隆枸杞VDE基因全长cDNA序列,生物软件分析VDE的生物学信息。构建VDE基因的原核表达载体pET-VDE,转化大肠后用IPTG诱导VDE过量表达;并构建体外反应体系对VDE表达蛋白酶功能进行验证。结果:LcVDE基因的ORF长1 413bp,编码的蛋白由470个氨基酸组成,分子量为53.61kDa,等电点为5.77。SDS-PAGE电泳结果表明,枸杞VDE基因在大肠杆菌中得到了过量表达。克隆基因表达蛋白进行紫黄质的脱环氧化反应,吸收光谱和HPLC的分析结果表明,表达蛋白催化了紫黄质的脱环氧化反应。结论:克隆得到的VDE基因编码的蛋白具有紫黄质脱环氧化酶的的功能与活性。     

光照下叶黄素循环与非辐射能量耗散的关系

离体玉米叶片在光照下叶黄素循环与非辐射能量耗散发生明显变化.随着光强提高,玉米黄质(Z)含量显著上升,单环氧玉米黄质(A)含量在中低光强时增加但在较强光照下略有降低,紫黄质(V)含量则呈下降趋势,但叶黄素循环组分库V+A+Z上升幅度不大;相同条件下非辐射能量耗散增强,表现为非光化学猝灭荧光参数(NPQ)明显上升,同时F_v/F_m下降.分析表明,(Z+0.5A)/(V+A+Z)与NPQ呈明显正相关,而与F_v/F_m呈显著负相关,(V+0.5A)/(V+A+Z)则与之相反.由此推测,离体条件下玉米叶片中Z的环氧化和V的脱环氧化明显与非辐射能量耗散和PSⅡ光能转化过程相关.     

弱光胁迫影响夏玉米光合效率的生理机制初探

大田条件下, 以普通夏玉米(Zea mays) ‘泰玉2号’为材料, 于授粉后1-20天遮光55% (+S), 以大田自然光照条件下生长的玉米作为对照(-S), 研究了遮光及恢复过程中玉米植株的光合性能、叶绿体荧光参数、叶黄素循环以及光能分配的变化, 初步揭示夏玉米开花后弱光条件下光适应的生理机制, 为玉米高产稳产提供理论依据。结果表明, 遮光后玉米穗位叶叶绿素含量及可溶性蛋白含量均减少, RuBP羧化酶和PEP羧化酶活性显著降低, 导致穗位叶净光合速率(P_n)迅速下降, 光饱和点也明显降低; 恢复初期P_n迅速升高, 光合关键酶活性有所增强。遮光后植株的最大光化学效率(F_v/F_m)、实际光化学效率(Ф_PSII)显著降低, 非光化学淬灭(NPQ)则显著升高, 而恢复初期植株穗位叶Ф_PSII有所升高, 表明突然暴露在自然光下的光合电子传递速率明显加快, 这与其光合速率及光合酶活性的趋势保持一致; 遮光处理对穗位叶叶黄素循环库的大小(紫黄质+花药黄质+玉米黄质(V + A + Z))影响不显著, 但使叶黄素循环的脱环氧化状态(A + Z)/(V + A + Z)增加; 遮光后植株分配于光化学反应的光能明显减少, 天线耗散光能比率显著增加, 恢复过程中植株主要以过剩非光化学反应的形式耗散过剩的光能。遮光后及恢复初期, 玉米植株的PSII原初光化学活性明显下降, 限制了光合碳代谢的电子供应从而抑制了光合作用, 主要依赖叶黄素循环途径进行能量耗散, 而在光照转换后遮光的玉米叶片在适应自然光过程中的光保护机制不断完善, 光合能力逐渐得到 恢复。     

小麦紫黄质脱环氧化酶(VDE) cDNA的克隆及表达

应用RT-PCR方法从小麦(Triticum aestivum L. cv.Xiaoyan 54)中克隆了紫黄质脱环氧化酶(violaxanthinde-epoxidase,VDE) cDNA,预测的蛋白质序列与拟南芥(Arabidopsis thaliana)、水稻(Oryza sati va)有很高的同源性.Southern杂交结果表明,在小麦中可能存在3个拷贝的紫黄质脱环氧化酶基因.Northern杂交结果表明它在绿色叶片中特异表达,在黄化小麦幼苗变绿过程中其mRNA水平受光诱导,并且强光增加了其mRNA在成熟叶片中的表达.     

低温强光胁迫下籼粳稻的PSⅡ光化学效率和膜脂过氧化表现

研究了温光胁迫下籼 (OryzasativaL .spp .indica)粳稻 (O .sativaL .spp .japonica)生育后期叶片荧光参数和膜脂过氧化的关系。结果表明 ,低温强光下水稻光合机构中PSⅡ的D1蛋白量下降 ,叶黄素循环组分中环氧玉米黄质 (A)和玉米黄质 (Z)的形成受抑 ,PSⅡ光化学效率 (Fv/Fm)和非光化学猝灭 (qN)明显下降。加之内源活性氧清除剂超氧物歧化酶 (SOD)活性降低 ,超氧阴离子自由基 (O-·2 )和膜脂过氧化产物丙二醛 (MDA)积累增加 ,导致光氧化发生。上述过程在籼粳稻间有明显差异 ,低温强光结合抑制剂处理证明 ,籼稻较粳稻对低温强光敏感和光氧化严重。相关分析表明 ,D1蛋白量分别与Fv/Fm 和 (A Z) / (A Z V)呈极显著的正相关关系 ,Fv/Fm 与MDA呈极显著的负相关关系。据此认为 ,逆境下Fv/Fm是预测光氧化的关键指标 ,D1蛋白合成能力和叶黄素循环的保护作用是其生理基础     

小麦紫黄质脱环氧化酶(VDE)cDNA的克隆及表达(英文)

应用RT-PCR方法从小麦(Triticum aestivum L.cv.Xiaoyan 54)中克隆了紫黄质脱环氧化酶(violaxanthinde-epoxidase,VDE)cDNA,预测的蛋白质序列与拟南芥(Arabidopsis thaliana)、水稻(Oryza sativa)有很高的同源性。Southern杂交结果表明,在小麦中可能存在3个拷贝的紫黄质脱环氧化酶基因。Northern杂交结果表明它在绿色叶片中特异表达,在黄化小麦幼苗变绿过程中其mRNA水平受光诱导,并且强光增加了其mRNA在成熟叶片中的表达。     

Variation in Volatile Leaf Oils of Eleven Eucalyptus Species Harvested from Korbous Arboreta (Tunisia)

Hydrodistillation of the dried leaves of eleven species of the genus Eucalyptus L 'Hér ., i.e., E. astringens Maiden , E. camaldulensis Dehnh ., E. diversifolia Bonpl ., E. falcata Turcz ., E. ficifolia F. Muell ., E. gomphocephala DC., E. lehmannii (Schauer ) Benth ., E. maculata Hook ., E. platypus Hook ., E. polyanthemos Schauer, and E. rudis Endl ., harvested from Korbous arboreta (region of Nabeul, northeast of Tunisia) in April 2006, afforded essential oils in yields varying from 0.1±0.1 to 3.8±0.1%, dependent on the species. E. astringens and E. ficifolia showed the highest and the lowest mean percentage of essential oil amongst all the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 138 components, representing 74.0 to 99.1% of the total oil. The contents of the different samples varied according to the species. The main components were 1,8‐cineole, followed by trans‐pinocarveol ( 1 ), spathulenol ( 2 ), α‐pinene, p‐cymene, (E,E)‐farnesol, cryptone, globulol ( 3 ), β‐phellandrene, α‐terpineol, viridiflorol, and α‐eudesmol. The principal‐component and the hierarchical‐cluster analyses separated the eleven Eucalyptus leaf essential oils into seven groups, each constituting a chemotype.     

Variation in Volatile Leaf Oils of Twelve Eucalyptus Species Harvested from Hajeb Layoun Arboreta (Tunisia)

Hydrodistillation of the dried leaves of twelve species of the genus Eucalyptus L' Hér ., i.e., E. brockwayi C. A. Gardn ., E. gracilis F. Muell ., E. gillii Maiden , E. largiflorens F. Muell ., E. loxophleba Benth ., E. occidentalis Endl ., E. oldfieldii F. Muell ., E. salmonophloia F. Muell ., E. sargentii Maiden , E. stricklandii Maiden , E. torquata Luehm ., and E. woodwardii Maiden , harvested from Hajeb Layoun arboreta (region of Kairouan, central Tunisia) in January 2005, afforded essential oils in yields varying from 0.5±0.1 to 5.7±0.5%, dependent on the species. E. sargentii and E. brockwayi provided the highest and the lowest percentage of essential oil amongst all the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 133 components, representing 92.9–98.8% of the total oil. The contents of the different samples varied according to the species. The main components were 1,8‐cineole, terpinen‐4‐ol, α‐pinene ( 2 ), p‐cymene, aromadendrene ( 1 ), globulol ( 5 ), trans‐pinocarveol ( 6 ), spathulenol ( 7 ), β‐eudesmol, torquatone ( 3 ), and 4‐methylpentan‐2‐yl acetate ( 8 ). The principal component analysis and the hierarchical clustering indicated that the volatile leaf oil composition of the twelve Eucalyptus species could be clearly differentiated.     

Variation in Volatile Leaf Oils of 13 Eucalyptus Species Harvested from Souinet Arboreta (Tunisia)

Hydrodistillation of the dried leaves of 13 species of the genus Eucalyptus L' Hér ., viz., E. bicostata Maiden, Blakely & Simmonds , E. cinerea F. Muell . ex Benth ., E. exerta F. Muell ., E. gigantea Hook . f ., E. gunnii Hook . f ., E. macarthurii Deane & Maiden ., E. macrorrhyncha F. Muell ., E. maidenii F. Muell ., E. odorata Behr ., E. pauciflora Sieber ex Sprengel , E. sideroxylon A. Cunn . ex Woolls , E. tereticornis Sm ., and E. viminalis Labill ., harvested from Souinet arboreta (region of Ain Draaham, north of Tunisia) in June 2006, afforded essential oils in yields varying from 0.5±0.2 to 3.9±0.4%, dependent on the species. E. cinerea and E. exerta provided the highest and the lowest percentage of essential oil amongst all the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 142 components, representing 81.5 to 98.9% of the total oil. The contents of the different samples varied according to the species. The main components were 1,8‐cineole ( 1 ), followed by cryptone, spathulenol ( 4 ), p‐cymene ( 2 ), viridiflorol ( 6 ), globulol ( 7 ), β‐eudesmol, α‐terpineol ( 5 ), limonene ( 8 ), D ‐piperitone, α‐pinene ( 3 ), cuminal, and γ‐eudesmol. The principal component and the hierarchical cluster analyses separated the 13 Eucalyptus leaf essential oils into three groups, each constituting a chemotype.     

Isolation of rfb Gene Clusters Directing the Synthesis of O Polysaccharides Consisting of Mannose Homopolymers and Serological Analysis of Lipopolysaccharides

Four serotypes of two genera, Escherichia coli O8 and O9 and Klebsiella O3 and O5, produce the O polysaccharides consisting of mannose homopolymers. Previously we reported the isolation and expression of E. coli O9 rfb in E. coli K-12 strains (Kido et al, J. Bacteriol., 171: 3629–3633, 1989). In this study, R' plasmids carrying his-rfb region of the other three strains were isolated and expressed in E. coli K-12 strain. Serological study of lipopolysaccharides (LPS) synthesized in E. coli K-12 strain was carried out. His-linked rfb genes from E. coli O9 and Klebsiella O3 directed the synthesis of O polysaccharides with the same antigenicity as those of the parental strains in E. coli K-12 strain. On the other hand, rfb genes from E. coli O8 and Klebsiella O5 directed the synthesis of O polysaccharides which were antigenically not identical but partially common to those of the parental strains. A rough strain derived from E. coli O8 synthesized LPS which showed the identical antigenicity as the wild strain when the his-rfb region of E. coli O8 was introduced. The results suggest that some genes located distantly from his are additionally required to complete the synthesis of O polysaccharides of E. coli O8 and Klebsiella O5.     

Variation in volatile leaf oils of five Eucalyptus species harvested from Jbel Abderrahman arboreta (Tunisia)

Hydrodistillation of the dried leaves of five species of the genus Eucalyptus L' Hér ., viz., E. dundasii Maiden , E. globulus Labill ., E. kitsoniana Maiden , E. leucoxylon F. Muell ., and E. populifolia Hook ., harvested from Jbel Abderrahman arboreta (region of Nabeul, northeast of Tunisia) in April 2006, afforded essential oils in yields varying from 0.9±0.3 to 3.8±0.6%, dependent on the species. E. globulus and E. Kitsoniana provided the highest and the lowest percentage of essential oil amongst the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 127 compounds, representing 93.8 to 98.7% of the total oil composition. The contents of the different samples varied according to the species. The main components were 1,8‐cineole ( 2 ; 4.7–59.2%), followed by α‐pinene ( 1 ; 1.9–23.6%), trans‐pinocarveol ( 6 ; 3.5–21.6%), globulol ( 8 ; 4.3–12.8%), p‐cymene ( 3 ; 0.5–6.7%), α‐terpineol (1.5–4.5%), borneol (0.2–4.4%), pinocarvone (1.1–3.8%), aromadendrene (1.4–3.4%), isospathulenol (0.0–1.9%), fenchol ( 4 ; 0.1–2.5%), limonene (1.0–2.4%), epiglobulol (0.6–2.1%), viridiflorol ( 9 ; 0.8–1.8%), and spathulenol (0.1–1.6%). E. leucoxylon was the richest species in 2 . Principal component analysis (PCA) and hierarchical cluster analysis (HCA) separated the five Eucalyptus leaf essential oils into four groups, each constituting a chemotype.     

Evolution alpiner Populationen vonEuphrasia (Scrophulariaceae): Chromosomenzählungen an diploiden und polyploiden Sippen aus den Ostalpen

Chromosome counts are reported for several E. Alpine taxa ofEuphrasia sect.Euphrasia. First records of diploidy for small-flowered taxa are 2n = 22 forE. inopinata andE. sinuata, related toE. minima (4 x). Aberrant E. AlpineE. hirtella is 2 x, just as the typical W. Alpine populations of this species. Tetraploidy, 2n = 44, has been found inE. pumila, close toE. stricta (also 4 x). The limitation of ploidy levels within sect.Euphrasia to 2 x and 4 x on the chromosome base number x = 11 is confirmed.

     

白花丹素对E.coli藻酸盐合成的抑制作用

细菌分泌的胞外多糖在生物被膜的形成和发展过程中发挥着重要作用。通过测定白花丹素对大肠埃希菌10389菌株(E.coli 10389)藻酸盐合成的影响及其对rse A和rpo E基因表达量的影响,探讨白花丹素对大肠埃希菌生物被膜(biofilm,BF)形成的抑制作用及机制。研究结果显示,白花丹素能抑制E.coli 10389生物被膜的形成,其抑杀E.coli 10389的最低抑菌浓度(minimum inhibitory concentration,MIC)和最低杀菌浓度(minimal bactericidal concentration,MBC)分别为16和64μg/mL。白花丹素对成熟BF内的细菌也有抑制和杀灭作用,其抑杀E.coli 10389成熟BF内细菌的MIC和MBC分别为64和128μg/mL。白花丹素能够抑制E.coli 10389藻酸盐的合成,其中1/2MIC的白花丹素作用E.coli 10389 24 h后,与对照组比,藻酸盐的合成量降低了34.83%(P0.01)。白花丹素可显著影响E.coli 10389 rse A和rpo E基因的相对表达量,其中1/2MIC的白花丹素作用E.coli 10389 24 h后,与对照组相比,rse A的表达量上调了17.43%,rpo E的表达量降低了12.8%(P0.05)。结果表明,白花丹素能够抑制E.coli 10389 BF的形成,其作用机制可通过影响rse A和rpo E的基因表达量,进而抑制藻酸盐的合成来抑制大肠埃希菌生物被膜的形成。     

The Chemical Diversity of Eucalyptus spp. Essential Oils from Plants Grown in Brazil

A chemical analysis of essential oils from leaves of eleven Eucalyptus L’Herit taxa, grown in Viçosa, Brazil were carried out. The identification and quantification of essential oils constituents were carried out by GC‐FID and GC/MS. The leaves of E. camaldulensis and E. tereticornis presented the highest oil content (3.00% and 2.30% respectively). In total, 48 compounds were identified in the oils. Higher levels of 1,8‐cineole were found for oils produced by E. microcorys (66.2%), E. urophylla (65.4%) and E. camaldulensis (44.8%) and the hybrid E. urophylla × E. grandis (33.0%). The oil from E. saligna was composed mainly by α‐pinene (92.3%). High concentrations of α‐phellandrene were found in the oils produced by E. camaldulensis (22.9%) and E. robusta (36.6%). The oils from E. grandis and E. pilularis were rich in p‐cymene (59.5% and 46.0%, respectively). Samples with high levels of 1,8‐cineole were classified by principal component analysis (PCA) using the accumulated variance of the PC1 and PC2 into major groups. Other samples were grouped based on their content of p‐cymene; α‐phellandrene, α‐ and β‐eudesmol; α‐pinene. The PCA allowed the separation and classification of samples with the highest levels of different compounds, a procedure that can help in the decision of grouping oils from different sources for industrial use.     

Pathotypic and molecular evolution of contemporary population of Puccinia striiformis f. sp. tritici in Egypt during 2016–2018

The contemporary races of Puccinia striiformis f. sp. tritici (Pst) in Egypt during 2016–2018 were differentiated based on virulence and molecular patterns. Virulence patterns based on the reaction of the 17 World/European differential sets carrying stripe rust resistance genes (Yr genes) resulted in ten races including four new (first recorded in Egypt) and six old (previously recorded in Egypt). The new races were identified as 64E0 (virulence [V] Yr4, Su), 0E16 (V Yr8, 19), 66E0 (V Yr4, 7, 22, 23, Su) and 4E130 (V Yr2, 6, 7, 25, HVII), while the old were 0E0 (avirulence), 2E0 (V Yr7, 22, 23), 2E16 (V Yr7, 8, 19, 22, 23), 4E0 (V Yr2, 6), 6E4 (V Yr2, 6, 7, 22, 23, 25) and 70E4 (V Yr2, 4, 6, 7, 22, 23, 25, Su). Cluster analysis differentiated Pst races based on virulence frequency to Yr genes. Simple sequence repeat (SSR) markers were used to detect the molecular polymorphism of the Pst races. Clustering separated the old and new races into two groups, indicating their common ancestry since the new races were very distinct from the old races. Although clustering based on virulence revealed some evolutionary patterns, where the new races 64E0 and 66E0 may have probably evolved from the old races (2E16, 2E0, 6E4, 70E4) and the new race 4E130 may be evolved from the joint race 4E0. However, clustering based on molecular patterns indicated that the new races appear to be genetically distinct and may represent an exotic introduction rather than a mutation in isolates of the old races. A weak association between virulence and molecular patterns revealed that they are independent of each other. The SSR markers did not correspond to the virulences in the pathogen. Further studies on the potential virulence genes of the detected Pst virulences are needed.