超高产水稻组合‘培矮64S/E32’的耐光氧化特性及其机理

甲基紫精(MV)介导的光氧化导致两个水稻品种‘汕优63’(目前我国大面积推广的杂交水稻)和‘培矮64S/E32’(新培育的超高产杂交水稻)细胞电解质渗漏率都增加,前者增加的量大于后者,显示‘培矮64S／E32’的细胞膜系统受光氧化的伤害小。光氧化条件下,‘培矮64S／E32’仍能维持较高的光合放氧能力(Amax,φi)、PSⅡ活性(Fv/Fm、φPSⅡ)和叶绿素荧光猝灭系数(qP、MPQ),而且光氧化引起‘培矮64S／E32’这些参数的下降幅度也小。另外,光氧化导致了两个水稻品种抗氧化酶SOD和APX活性增加,‘培矮64S／E32’增加的幅度约为‘汕优63’的3倍。结果 表明超高产水稻具有更强的耐光氧化能力。     

超高产杂交稻剑叶中C4途径酶活性和稳定碳同位素分异作用的变化

以超高产杂交水稻(Oryza sativa L.)"培矮64S/E32"和多年来大面积推广的杂交稻"汕优63"为材料,研究孕穗后剑叶中C4途径酶和对稳定碳同位素分异作用的变化.结果表明,籽粒灌浆期(移栽后68～75 d)的两个品种剑叶中NADP-MDH活性最高,随后下降;超高产杂交水稻"培矮64S/E32"的NADP-MDH的活性明显高于"汕优63";PEPCase和NADP-ME活性在黄熟期之前的叶片中持续上升.不同生育期的叶片与籽粒的△1aC值相近(19.49‰～19.82‰),在成熟期时较高.超高产水稻"培矮64S/E32"叶片的平均△13C值比"汕优63"高0.43‰.     

超高产杂交稻剑叶中C4途径酶活性和稳定碳同位素分异作用的变化

以超高产杂交水稻(Oryza sativa L．)“培矮64S／E32”和多年来大面积推广的杂交稻“汕优63”为材料,研究孕穗后剑叶中C4途径酶和对稳定碳同位素分异作用的变化。结果表明,籽粒灌浆期(移栽后68～75d)的两个品种剑叶中NADP—MDH活性最高,随后下降;超高产杂交水稻“培矮64S／E32”的NADP-MDH的活性明显高于“汕优63”;PEPcase和NADP—ME活性在黄熟期之前的叶片中持续上升。不同生育期的叶片与籽粒的△^13C值相近(19．49‰～19．82‰),在成熟期时较高。超高产水稻“培矮64S／E32”叶片的平均△^13C值比“汕优63”高0．43‰。     

超高产水稻组合‘培矮64S/E32’的耐光氧化特性及其机理

甲基紫精（MV）介导的光氧化导致两个水稻品种‘汕优63’(目前我国大面积推广的杂交水稻)和‘培矮64S/E32’（新培育的超高产杂交水稻）细胞电解质渗漏率都增加,前者增加的量大于后者,显示‘培矮64S/E32’的细胞膜系统受光氧化的伤害小。光氧化条件下,‘培矮64S/E32’仍能维持较高的光合放氧能力（Amax、Φi）、PSⅡ活性（Fv/Fm、ΦPSⅡ）和叶绿素荧光猝灭系数（qP、NPQ）,而且光氧化引起‘培矮64S/E32’这些参数的下降幅度也小。另外,光氧化导致了两个水稻品种抗氧化酶SOD和APX活性增加,‘培矮64S/E32’增加的幅度约为‘汕优63’的3倍。结果表明超高产水稻具有更强的耐光氧化能力。     

超高产杂交稻剑叶衰老过程中的抗氧化性的变化

与对照种汕优63相比,超高产水稻组合培矮64S/E32的剑叶在生长后期具有更高的抗氧化酶(抗坏血酸过氧化物酶APX和谷胱甘肽还原酶GR)活性和小分子抗氧化剂(抗坏血酸Vc、总Vc、还原型谷胱甘肽GSH和β-胡萝卜素)含量,高的清除有机自由基DPPH·能力,更低的膜脂过氧化产物丙二醛含量。这表明培矮64S/E32剑叶在生长后期有强的抗氧化性,这种强抗氧化性与超高产水稻在结实后期剑叶中较慢的叶绿素和蛋白质降解速度相一致。     

自然条件下不同高产稻生育后期剑叶叶绿素荧光和膜脂过氧化的表现

以籼型(Oryza sativa L.)杂交组合汕优63为对照,以中粳9516、两系亚种间杂交组合培矮64S/E32、培矮64S/9311、亚种间三系杂交稻冈优881和两系杂交组合X07S/紫恢100为材料,研究其在生育后期(抽穗-成熟)自然条件下剑叶的叶绿素衰减、CO2交换、叶绿素荧光参数和膜脂过氧化表现.结果表明: 水稻在生育后期伴随叶绿素衰减,其叶内的原初光化学效率Fv/Fm、PSⅡ非环式电子传递效率ΦPSⅡ、电子流传递速率ETR都有相应地下降,这种光能转化的障碍使多余的光能传递给PSⅡ的还原侧,产生O(-)/(*)2累积,发生膜脂过氧化和MDA的积累,引起光合色素及光合膜的破坏,发生光氧化早衰.这种现象在品种间有明显差异,耐光氧化的粳稻9516,其叶内的 Fv/Fm、ΦPSⅡ、ETR、qP下降较少,具有较稳定的光能转化能力,不易早衰,具有较高的结实率;而对光氧化敏感的籼稻汕优63其叶内的Fv/Fm、ΦPSⅡ、ETR,光化学猝灭参数qP下降较多,易发生膜脂过氧化,导致叶片早衰,影响水稻灌浆结实和产量;而二系的和三系的杂交稻的耐光氧化特性和早衰表现居于中间.从水稻超高产育种的角度出发,在目前株型良好的基础上,兼顾杂种优势和防止早衰两方面考虑,在母本中利用粳型或带有粳型基因的不育系是育种上一个值得重视的策略.     

超高产杂交稻两优培九的光合作用、光抑制和C4途径酶特性

比较研究了超高产杂交稻(Oryza sativa L.)两优培九和常规杂交稻汕优63剑叶的光合气体交换、光抑制, 以及其剑叶和稃片中的C₄酶活性. 发现两优培九和汕优63的光饱和同化速率(Asat)与汕优63相差无几, 但是, 其表观量子效率(AQY)、羧化效率(CE)和CO₂同化的量子效率(FCO₂)都远远高于汕优63. 强光条件下, 超高产杂交稻两优培九表现出比汕优63更强的抗光抑制能力, 并且具有较高的以叶黄素循环为量度的非辐射能量耗散. 此外, 两优培九的剑叶和稃片中的C₄途径酶活性均高于汕优63. 这些结果表明, 较高的光能和CO₂利用效率、较强的抗光抑制能力, 以及剑叶和稃片中C₄途径的较高表达可能是超高产杂交稻两优培九高产的重要保证.     

超高产水稻剑叶衰老过程中PSⅡ激发压与 Rubisco大、小亚基含量的相关性

研究了大田生长条件下两系超高产杂交水稻(Oryza sati va L.)"两优培九"和我国大面积推广的三系杂交水稻"汕优63"从灌浆期到收获期剑叶PSⅡ光化学特性和Rubjsco大、小亚基含量的变化.结果表明:可溶性蛋白质和叶绿素含量随剑叶生长时间的延长先缓慢下降,后期有一个快速降解的过程,"汕优63"降解的速率高于"两优培九";Fv/Fm和qP都呈下降的趋势,qN则是先降然后上升.激发压(1 qP)在前期的变化较为平稳,后期则急剧增加,"汕优63"较"两优培九"增加快.Rubi Sco大、小亚基的含量与叶绿素、可溶性蛋白含量一样在前期下降比较慢,后期也有一个快速降解的过程,"汕优63"比"两优培九"降解快.激发压的增加与Rubisco大、小亚基的降解呈显著的线性相关性.我们推测PSⅡ激发压的急剧增加可能诱发了水稻剑叶的快速衰老过程."两优培九"高产的重要生理原因之,可能是它比"汕优63"有更强的光合能力并能维持更持久和较高的光合功能期.     

超高产杂交稻在强光胁迫及其恢复进程中的PSⅡ活性和叶黄素循环

研究了两系超高产杂交稻(Oryza sativa L.)"两优培九"和"华安3号"以及多年来大面积推广的三系杂交稻"汕优63"剑叶的PSⅡ活性和叶黄素循环对强光胁迫及其恢复进程的响应.结果表明,在2 000 μmol photons*m-2*s-1的强光胁迫下,3个杂交稻的PSⅡ光化学最大效率(Fv/Fm)、开放的PSⅡ反应中心捕获激发能效率(Fv′/Fm′)和PSⅡ的实际光化学转能效率(ΦPSⅡ)都随着光抑制进程而下降,其中以"汕优63"下降的幅度最大.光抑制过程中,杂交稻叶黄素循环的紫黄素(V)组分迅速下降,与此同时,脱环氧化组分环氧玉米黄素(A)和玉米黄素(Z)迅速积累,而超高产杂交稻"两优培九"和"华安3号"的A和Z的积累速度大大高于"汕优63".伴随A和Z的快速积累,它们的叶黄素循环的脱环氧化状态(DES)迅速上升,并在半小时左右基本达到最大值,其中"两优培九"和"华安3号"DES的上升速率仍然较"汕优63"高.光抑制处理结束后,转移到弱光(70 μmol photons*m-2*s-1)条件下恢复过程中,两个超高产杂交稻的Fv/Fm、Fv′/Fm′和ΦPSⅡ的恢复速率和恢复水平都高于"汕优63".同时,它们的叶黄素循环组分V、A、Z以及DES都逐渐恢复,但"两优培九"和"华安3号"的恢复速率和恢复水平仍然要优于"汕优63".以上结果说明,超高产杂交稻"两优培九"和"华安3号"较对照品种"汕优63"具有更强的抗光抑制及光保护能力,同时在光抑制结束后又能够更迅速地恢复光合功能,较强的抗光抑制能力和较高的恢复能力可能是超高产杂交稻高产的重要生理基础之一.     

在光氧化条件下不同类型高产稻的叶绿素荧光特性和膜脂过氧化特点

用不同类型高产稻(Oryza sativa L.)粳稻9516、具有粳型成分的两系法亚种间杂交稻培矮64/E32、两优培九(培矮64/9311)和籼型杂交稻X07S/紫恢100、冈优881、汕优63为材料,研究了孕穗期叶片在光氧化条件下的叶绿素荧光特性和膜脂过氧化表现.光氧化处理后,与籼型杂交稻比较,粳稻和具有粳型组分的亚种间杂交稻的PSⅡ原初光化学效率(Fv/Fm)、PSⅡ的线性电子传递的量子效率(ΦPSⅡ)和光化学猝灭系数(qP)下降的较少;超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)诱导的活性较高,活性氧 (O(-)/()2、H2O2)和丙二醛(MDA)的产生积累较少,叶绿素和蛋白质含量下降较少,表现出耐光氧化特性,这与在自然条件下生育后期叶绿素含量变化相一致.相关分析表明它们的耐光氧化特性与结实率密切相关,说明耐光氧化品种抗早衰,有利籽粒充实.这些结果启示我们:从超高产育种出发,兼顾杂种优势利用和抗早衰两方面考虑,在母本不育系中引入粳型成分是一个值得重视的育种策略.     

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