GA3对NaCl胁迫下‘泡桐1201''幼苗生理代谢及离子吸收的影响

为探究赤霉素(GA₃)对NaCl胁迫下‘泡桐1201’幼苗生长的缓解效应及生理机制，该研究以‘泡桐1201’幼苗为材料，设置不同的NaCl、GA₃浓度，测定分析GA₃缓解NaCl胁迫下泡桐幼苗的生理指标、光合指标及离子转运能力。结果表明：(1)150 mmol·L^-1NaCl胁迫下泡桐幼苗的生长量显著下降(P<0.05),下降量超过50%;适宜浓度的外源GA₃显著提高泡桐幼苗的株高、根长及生物量，400 mg·L^-1的GA₃处理干重较A0增加69.71%。(2)随着GA₃浓度的增加，3种抗氧化酶(SOD、POD、CAT)活性显著提高，MDA含量显著降低，叶绿素含量、气体交换参数(P_n、T_r、C_i、G_s)均增大，光合效率提高，各离子含量(K⁺、Ca²⁺、Mg²⁺     

盐胁迫对裸果木幼苗生长和叶片相关生理指标的影响

裸果木起源于古地中海,为亚洲中部荒漠区分布的第三纪孑遗植物种,对研究旱生植物演化过程具有重要的科学价值。以一年生裸果木(Gymnocarpos przewalskii)实生苗为材料,在盆栽条件下用质量浓度为0.4%、0.8%、1.2%和1.6%的NaCl溶液进行盐胁迫处理,测定各NaCl处理下裸果木幼苗叶片的抗氧化酶活性、渗透调节物质含量、叶绿素含量、相对电导率(REC)、丙二醛(MDA)含量以及株高、基径,根、茎、叶、总干重,根冠比变化,探讨裸果木幼苗对盐胁迫的生理耐受性。结果显示,(1)随着盐胁迫程度的加重,裸果木幼苗株高、基径,以及根、茎、叶干重和总干重整体呈下降趋势,而根冠比呈上升趋势;裸果木幼苗株高、基径和根干重在0.4%NaCl处理下较对照变化不显著,但其茎干重、叶干重和总干重在各NaCl处理下均显著低于对照。(2)随着盐胁迫程度的加重,裸果木幼苗叶片的可溶性糖(SS)含量、可溶性蛋白(SP)含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性均先升高后降低,而脯氨酸(Pro)含量、过氧化氢酶(CAT)活性、REC、MDA含量均呈持续升高趋势;在0.8%NaCl处理...     

NaCl胁迫对大黄龙船花生长及生理生化的影响

为探讨大黄龙船花(Ixora collinea‘Gillettese How’)的耐盐特性,对NaCl 胁迫下大黄龙船花扦插幼苗的生长和生理生化指标进行了研究.结果表明,NaCl 胁迫处理后大黄龙船花叶片中的丙二醛含量、相对电导率和脯氨酸含量升高,膜伤害程度加大.叶片相对电导率、丙二醛含量和脯氨酸含量与NaCl 浓度间存在显著正相关关系.随着盐胁迫浓度的增加,叶片总叶绿素、可溶性蛋白质含量呈下降趋势,两者与NaCl 浓度间呈显著负相关关系.可溶性糖含量、SOD 活性与NaCl 浓度间的相关性不显著.较低浓度的盐胁迫(0.2%~0.6%)对大黄龙船花的生长有轻微的抑制作用,而0.8%~1.5% 的高浓度盐胁迫显著影响生理生化指标.     

NaCl胁迫对醋栗番茄、樱桃番茄和番茄幼苗生长、叶片气体交换和离子平衡的影响

以醋栗番茄( Solanum pimpinellifolium Linn.)、樱桃番茄品种‘秦皇贵妃红’( S. lycopersicum var. cerasiforme‘Qinhuangguifeihong’)和番茄品种‘浙粉202’(S. lycopersicum‘Zhefen 202’)幼苗为材料,研究了0(对照)、100、200 mmol·L-1 NaCl胁迫对其生长、叶片气体交换参数和离子平衡的影响。结果表明：在100和200 mmol·L-1 NaCl胁迫下,‘秦皇贵妃红’和‘浙粉202’幼苗单株总干质量的降幅较大,醋栗番茄的降幅较小。 NaCl胁迫明显增加醋栗番茄幼苗的根冠比,但不同胁迫条件下‘秦皇贵妃红’和‘浙粉202’幼苗的根冠比差异不显著。与对照相比,在100 mmol·L-1 NaCl胁迫下,醋栗番茄幼苗叶片的净光合速率( Pn)、胞间CO2浓度( Ci)和蒸腾速率( Tr)的降幅明显低于‘秦皇贵妃红’和‘浙粉202’,而醋栗番茄幼苗叶片气孔导度(Gs)的降幅明显高于后二者;在200 mmol·L-1 NaCl胁迫下,三者叶片Pn、Gs、Ci和Tr值的降幅接近。在100和200 mmol·L-1 NaCl胁迫下,醋栗番茄、‘秦皇贵妃红’和‘浙粉202’幼苗叶片的水分利用效率和气孔限制值均较各自对照显著升高,其中‘秦皇贵妃红’的增幅最大。在100和200 mmol·L-1 NaCl胁迫下,醋栗番茄、‘秦皇贵妃红’和‘浙粉202’幼苗根、茎和叶中Na+含量均较各自对照显著升高,而K+含量和K+/Na+比总体上较各自对照显著降低。与对照相比,经不同浓度NaCl处理后醋栗番茄幼苗根、茎和叶的Na+含量增幅以及K+含量降幅在供试3种植物中均最小,而其不同部位的K+/ Na+比总体上较高。上述研究结果表明：醋栗番茄的耐盐性较强,‘秦皇贵妃红’次之,‘浙粉202’较弱。 NaCl胁迫显著抑制‘秦皇贵妃红’和‘浙粉202’幼苗根的生长,但显著促进醋栗番茄幼苗根的生长,使其维持较强的耐盐性,且NaCl胁迫下醋栗番茄对Na+的吸收和运输减少,以维持体内的离子平衡及较强的光合作用。     

NaCl胁迫对超大甜椒种子萌发及幼苗生长的影响

以超大甜椒种子和幼苗为材料,采用水培法研究低、中、高浓度(50、150、250 mmol·L-1)NaCl胁迫对其种子萌发和幼苗生长的影响.结果显示:(1)低浓度NaCl处理促进种子萌发,而中、高浓度NaCl处理抑制种子萌发;NaCl处理第18天时,高浓度NaCl处理植株全部死亡,其余各处理植株苗高、叶面积、地上部鲜重和干重均随处理浓度升高而下降,但低浓度NaCl能刺激超大甜椒的根系生长.(2)低、中浓度NaCl处理时,植株叶绿素含量未受到大的影响,类胡萝卜素含量却随胁迫时间延长微量升高;在盐胁迫7 d的周期内,低、中浓度NaCl处理植株MDA含量、SOD活性和可溶性糖含量均随浓度升高及时间延长显著增加,脯氨酸含量在低浓度下变化不明显而中浓度下显著升高;在高浓度NaCl处理3 d中,MDA含量急剧升高,SOD活性先升高后下降,脯氨酸和可溶性糖含量显著增加.研究发现,NaCl胁迫浓度越高对超大甜椒种子萌发和幼苗生长的抑制效应越明显;低中浓度NaCl处理幼苗能通过自身的抗氧化酶清除系统和渗透调节物质来抵抗胁迫引起伤害,类胡萝卜素可能也有一定的抗胁迫作用,而高浓度NaCl处理增加了膜脂过氧化程度,严重影响了活性氧和渗透调节物质的正常代谢.     

Cd胁迫对紫花苜蓿种子发芽及幼苗生理生化特性的影响

以‘甘农3号’紫花苜蓿(Medicago sativa L.cv.‘Gannong 3’)品种为试验材料,研究不同浓度Cd胁迫对紫花苜蓿种子萌发及幼苗生理生化特性的影响。结果显示:(1)Cd胁迫显著抑制紫花苜蓿种子萌发及幼苗生长,种子发芽势、发芽率及幼苗的胚芽长、胚根长和干重均随着Cd处理浓度提高显著降低,且对发芽势的抑制作用大于发芽率,对胚根生长的抑制作用大于胚芽。(2)Cd胁迫第4d时,萌发种子中蛋白水解酶的活性受到显著抑制,可溶性蛋白和可溶性糖含量显著降低。(3)Cd胁迫第10d时,随着Cd胁迫浓度的增加,苜蓿幼苗的超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、愈创木酚过氧化物酶(GPX)活性均先升高后降低,过氧化氢酶(CAT)活性持续下降,超氧阴离子自由基产生速率、H2O2含量和丙二醛(MDA)含量均显著增加。研究表明,低浓度Cd胁迫下,苜蓿幼苗抗氧化系统清除活性氧的能力上升,高浓度Cd胁迫下,苜蓿幼苗抗氧化系统活性下降,膜脂过氧化程度加剧,活性氧的过量积累是Cd伤害苜蓿幼苗和其生物量下降的主要原因。     

等渗Ca(NO3)2和NaCl胁迫对黄瓜幼苗生长及渗透调节物质含量的影响

采用营养液培养方法,以耐盐性较弱的‘津春2号’黄瓜品种为试材,研究了等渗Ca(NO3)2和NaCl胁迫对黄瓜幼苗生长、根系电解质渗透率、根系活力、Na+和K+含量及渗透调节物质含量的影响。结果显示:(1)在84mmol.L-1 NaCl和56mmol.L-1 Ca(NO3)2等渗胁迫下,黄瓜幼苗鲜重和干重均显著下降,且NaCl处理下降的幅度大于等渗Ca(NO3)2处理。(2)NaCl主要通过对黄瓜根系的伤害来抑制植株生长,表现为根系活力下降、根系质膜透性增大、Na+大量积累、K+含量显著下降、Na+/K+明显上升,最终导致根冠比下降;而Ca(NO3)2处理对根系质膜透性、K+含量、Na+/K+的影响均小于NaCl胁迫,且根系活力和根冠比上升,但Ca(NO3)2胁迫后叶片含水量和渗透调节能力均小于NaCl胁迫。(3)NaCl胁迫条件下,黄瓜幼苗内渗透调节物质以可溶性糖为主,而Ca(NO3)2胁迫以可溶性蛋白为主。研究表明,NaCl胁迫对黄瓜幼苗的伤害大于等渗Ca(NO3)2,NaCl主要通过破坏根系质膜结构影响植株生长,而Ca(NO3)2主要通过引起地上部生理干旱来影响植株生长。     

外源NO对NaCl胁迫下黄瓜幼苗生长和根系谷胱甘肽抗氧化酶系统的影响

以津春2号黄瓜为材料,采用营养液水培的方法,研究了外源一氧化氮(NO)对黄瓜幼苗生长和根系谷胱甘肽抗氧化酶系统的影响.结果表明,(1)正常生长条件下添加NO能促进黄瓜幼苗生长,而添加亚甲基蓝(MB-1)显著抑制黄瓜幼苗的生长;(2)添加NO显著缓解了NaCl胁迫对黄瓜幼苗生长的抑制,提高根系还原型谷胱甘肽(GSH)含量、抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)活性,而氧化型谷胱甘肽(GSSG)含量略有下降,同时缓解了NaCl胁迫下抗坏血酸(ASA)含量的下降幅度;(3)NaCl胁迫下添加NO的同时添加MB-1可部分解除NO的作用,与NaCl胁迫下单独添加NO处理比较,GR活性、GSH和ASA含量均降低,GSSG含量提高,APX先升高后下降.研究发现,外源NO可能通过鸟苷酸环化酶(cGC)介导来调节NaCl胁迫下黄瓜幼苗根系GR活性和GSH、GSSG、ASA含量,提高抗氧化酶活性和非酶抗氧化物质含量,增强植株对活性氧的清除能力,减少膜脂过氧化,缓解NaCl胁迫对黄瓜幼苗造成的伤害.     

盐胁迫对西瓜幼苗活性氧代谢和渗透调节物质含量的影响

采用营养液培养法,以耐盐性较强的'秀雅'和耐盐性较弱的'秀丽'西瓜品种为材料,研究了不同浓度NaCl胁迫对两品种西瓜幼苗活性氧代谢和渗调物质含量的影响.结果显示:NaCl胁迫抑制了西瓜幼苗的生长,耐盐性较强的'秀雅'受抑制程度明显小于耐盐性较弱的'秀丽';随NaCl浓度提高,叶片O(-)/(·)2产生速率、MDA含量和质膜相对透性显著增加,'秀丽'的增加幅度明显大于'秀雅';POD活性在低浓度NaCl下降低而高浓度下升高,CAT和APX活性及抗坏血酸含量随NaCl浓度提高而显著增加,SOD活性随NaCl浓度变化的规律两品种有所不同;脯氨酸、可溶性糖含量随NaCl浓度提高而显著增加,可溶性蛋白含量在较低浓度NaCl下增加而高浓度下降低;除可溶性蛋白外,50 mmol·L-1以上NaCl胁迫下'秀雅'抗氧化酶活性、抗坏血酸和渗调物质含量均明显高于'秀丽'.研究表明:NaCl胁迫严重抑制了西瓜幼苗的生长,破坏了幼苗细胞膜结构,影响了活性氧和渗调物质的正常代谢,耐盐性较强的'秀雅'受抑制程度和脂质过氧化程度较低,与其抗氧化酶活性和渗调物质含量较高密切相关.     

外源Ca(NO_3)_2对NaCl胁迫下番茄幼苗生理特征的影响

以番茄品种'农城906'和"毛粉802'幼苗为材料,利用Hoagland基础培养液,研究在150 mmol/L NaCl胁迫下外源10、20、30和40 mmol/L Ca(NO3)2对番茄植株盐胁迫的缓解作用.结果显示,(1) NaCl胁迫显著降低了2个品种幼苗地上和地下部分干重、叶片叶绿素含量和根系活力,增加了幼苗的可溶性糖含量、细胞膜透性和MDA含量,同时使其CAT、POD、SOD活性显著降低;(2)添加20 mmol/L Ca(NO3)2能够有效提高盐胁迫条件下幼苗的地上和地下部干重,缓解叶绿素的降解和根系活力的下降,增加幼苗体内可溶性糖含量,降低叶片质膜透性和MDA含量,增强幼苗体内POD、CAT等细胞保护酶活性,但随着Ca(NO3)2浓度的继续增加,这种缓解作用逐渐减小.研究表明,一定浓度的外源Ca(NO3)2能有效缓解NaCl对番茄幼苗的生长和生理伤害,在一定程度上增强番茄幼苗对盐胁迫的耐受力,并以20 mmol/L Ca(NO3)2对NaCl胁迫的缓解效果最佳.     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various     

Pathogenic Characterization and Full Length Genome Sequence of a Reassortant Infectious Bursal Disease Virus Newly Isolated in Pakistan

<正>Dear Editor,Infectious bursal disease (IBD) is one of the most important diseases of the poultry. The IBD virus (IBDV), a nonenveloped virus belonging to the Birnaviridae family with a genome consisting of two segments of double-stranded RNA (segments A and B), targets B lymphocytes of bursa of Fabricious leading to immunosuppression. In Pakistan,poultry farming is the second biggest industry and IBD is the second biggest disease threating the poultry sector.However, there is limited genome information of IBDV