茉莉酸介导丛枝菌根真菌诱导番茄抗早疫病的机制

丛枝菌根真菌的定殖可以提高寄主植物的抗病性,但机制并不十分清楚。利用番茄茉莉酸信号转导途径前系统素过表达材料35S::PS、茉莉酸合成突变体spr2、茉莉酸信号识别突变体jai1及其野生型CM 4个不同基因型材料,分别在根系接种丛枝菌根真菌摩西斗管囊霉(Funneliformis mosseae, Fm),待菌根形成后,在叶片外源喷施10 mL 0.5μmol/L茉莉酸甲酯(MeJA)和接种番茄早疫病病原菌(Alternaria solani, As),比较不同基因型抗病防御反应以及对早疫病抗性的差异。结果表明:预先接种菌根真菌的CM和35S::PS番茄,在叶片接种病菌5 d和10 d后,其叶片中过氧化物酶(POD)、多酚氧化酶(PPO)和脂氧合酶(LOX)活性以及丙二烯氧化物环化酶基因(AOC)和茉莉酸信号受体基因(COI1)的转录水平显著高于只接种早疫病菌的处理、只接种菌根菌的处理以及未进行任何处理的健康植株,其早疫病发病率和病情指数也显著降低;外源喷施MeJA可增强预先接种菌根菌的CM和35S::PS番茄植抵抗早疫病的能力。与此同时,对预先接种菌根菌的spr2番茄外源喷施MeJA后接种早疫病菌,其酶活性和基因转录水平显著高于其他4个处理,发病率和病情指数也明显降低。然而,对jai1番茄进行MeJA处理不能增强其防御反应和抗病性。可见,丛枝菌根真菌侵染诱导番茄抗早疫病是与茉莉酸信号途径密切相关的。     

灰色链霉菌YD3309菌丝体抗菌活性成分研究

采用生物活性跟踪法,从一株灰色链霉菌菌丝体中分离得到2个具有抑菌活性的化合物,通过核磁共振波谱和质谱等技术鉴定2个化合物的结构为新刺孢霉素A(1)和N-乙酰基色氨醇(2);化合物1首次从放线菌中分离得到。抑菌活性测定结果表明:化合物1和2对番茄灰霉病菌(Botrytis cinerea)、茄子黄萎病菌(Verticillium dahliae)和辣椒枯萎病菌(Fusarium oxysporum)等多种蔬菜病原真菌有抑制作用,其中化合物1对番茄灰霉病菌和番茄早疫病菌菌丝具有强烈的抑制作用,化合物2对茄子黄萎病菌的菌丝具有强烈的抑制作用;化合物1对番茄灰霉病菌和番茄早疫病菌菌丝生长的半抑菌浓度(IC_(50))分别为30.6和28.8 mg/L,化合物2对茄子黄萎病菌菌丝生长的半抑菌浓度(IC50)为34.3 mg/L。     

番茄早疫病菌Hogl MAPK同源基因AsHogl的表达特性及其与抗药性的关联性

根据几种丝状真菌Hogl MAPK(丝裂原活化蛋白激酶)的保守氨基酸序列设计简并引物,从番茄早疫病菌Alternaria solani中扩增出MAPK同源基因的部分片段,命名为AsHogl.用Real-time RT-PCR技术比较了AsHogl在异菌脲敏感菌株和抗性菌株中的表达特性.结果表明,敏感菌株QX21经0.8mol/L NaCl和2mg/L异菌脲处理后,AsHogl相对表达量持续升高,在12h达到最大值,分别为对照的4.12倍和25.23倍,16h略有降低;而室内诱导抗性突变体和田间抗性菌株经相同处理后的AsHogl表达量变化不大,且明显低于敏感菌株.由此推测,番茄早疫病菌AsHogl基因表达特征与其对异菌脲抗药性相关.研究结果为深入研究病原菌对异菌脲抗药性的分子机理、建立抗药性分子监测技术、延缓和防止抗药性的产生及发展奠定了一定的理论基础.     

小麦内生细菌的分离及其对小麦纹枯菌的拮抗作用*

利用涂布平板法从小麦根系中分离出8株内生细菌,从中筛选出1株对小麦纹枯菌(Rhizoctoniacerealis)具有拮抗作用的内生菌。室内测定该菌株培养液对小麦纹枯病菌的抑制作用,结果发现,小麦纹枯病菌在培养液中生长缓慢,培养6d后菌丝量与对照相比下降了89%,同时发现病菌菌丝生长畸形,出现断裂和细胞壁瓦解。双抗标记法测定该拮抗菌在小麦根系中的定殖情况,发现该菌能够在根系中长期定殖。初步的鉴定结果表明该菌为蜡样芽孢杆菌。     

侧孢芽孢杆菌Bl13对番茄早疫病防治效果及机制

以对番茄早疫病原菌有良好拮抗效果的侧孢芽孢杆菌Bl13为研究对象,采用盆栽试验,通过测定番茄株高、茎粗、番茄早疫病病情指数、叶片内防御酶活性以及根区土壤微生物多样性、微生物群落结构组成等指标,探究侧孢芽孢杆菌Bl13防治番茄早疫病的效果及机制。结果表明: 接种Bl13可显著降低番茄早疫病的病情指数,提高叶片内多酚氧化酶(PPO)、过氧化物酶(POD)等防御酶活性,降低病害对植物地上部分及根系生长发育的影响。同时,改善番茄根区土壤微生物群落结构,使芽孢杆菌属、假单胞菌属等常见有益菌属相对丰度显著提高,油壶菌属、血赤壳属相对丰度显著降低。侧孢芽孢杆菌Bl13可通过提高番茄叶片内防御酶活性并增加根区中有益微生物的数量来增强植物对番茄早疫病的抗性,从而实现对番茄早疫病的防治。     

丛枝菌根菌丝桥介导的番茄植株根系间抗病信号的传递

菌根菌丝桥是植物间在地下进行物质交流的通道, 但它能否作为植物间地下化学通讯的通道来传递抗病信号则缺乏研究. 本文利用丛枝菌根真菌（AMF）摩西球囊霉在供体与受体番茄植株间建立菌丝桥, 对供体植株接种早疫病病原菌茄链格孢菌, 研究供体与受体番茄植株根系间是否存在抗病信号的传递. 荧光定量PCR检测表明, AMF侵染后的供体番茄植株再接种病原菌, 其根系中苯丙氨酸解氨酶基因（PAL)、脂氧合酶基因（LOX）和几丁质酶基因（PR₃）的转录水平显著高于仅接种病原菌、未接种病原菌和AMF, 以及只接种AMF的番茄植株. 更重要的是, 与供体有菌丝桥连接的受体番茄根系中PAL、LOX和PR₃的基因的表达量也显著高于无菌丝桥连接、菌丝桥连接被阻断以及有菌丝桥连接但供体植物未接种病原菌的处理,3个基因最高转录水平达到无菌丝桥连接对照受体植物的4.2、4.5和3.5倍. 此外, 供体植株根系启动防御反应的时间（18和65 h）比受体（100和140 h）早. 表明病原菌诱导番茄供体根系产生的抗病信号可以通过菌丝桥传递到受体根系.     

番茄早疫病菌Hog1 MAPK同源基因AsHog1的表达特性及其与抗药性的关联性

根据几种丝状真菌Hog1 MAPK(丝裂原活化蛋白激酶)的保守氨基酸序列设计简并引物,从番茄早疫病菌Alternaria solani中扩增出MAPK同源基因的部分片段,命名为AsHog1。用Real-timeRT-PCR技术比较了AsHog1在异菌脲敏感菌株和抗性菌株中的表达特性。结果表明,敏感菌株QX21经0.8mol/L NaCl和2mg/L异菌脲处理后,AsHog1相对表达量持续升高,在12h达到最大值,分别为对照的4.12倍和25.23倍,16h略有降低;而室内诱导抗性突变体和田间抗性菌株经相同处理后的AsHog1表达量变化不大,且明显低于敏感菌株。由此推测,番茄早疫病菌AsHog1基因表达特征与其对异菌脲抗药性相关。研究结果为深入研究病原菌对异菌脲抗药性的分子机理、建立抗药性分子监测技术、延缓和防止抗药性的产生及发展奠定了一定的理论基础。     

猪场沼液对蔬菜病原菌的抑制作用

用不同贮存时间的猪场沼液对7种蔬菜病原菌的抑制作用进行了研究。结果表明,新鲜猪场沼液原液对番茄灰霉病菌、番茄早疫病菌、辣椒疫病菌、黄瓜炭疽病菌和茄子灰霉病菌有较强的抑制作用,沼液贮存对番茄灰霉病菌、番茄早疫病菌和茄子灰霉病菌的抑制效果没有显著影响,但对辣椒疫病菌和黄瓜炭疽病菌的抑制效果影响显著;新鲜猪场沼液滤液对番茄灰霉病菌和茄子灰霉病菌有较强的抑制作用,沼液滤液贮存对番茄灰霉病菌和茄子灰霉病菌的抑菌效果没有显著影响。     

番茄早疫病菌拮抗菌发酵液稳定性分析

目的:对番茄早疫病菌拮抗菌ZJNU27发酵液稳定性进行分析,从而为抑菌活性物质的分离纯化提供一定理论依据.方法:以番茄早疫病菌为指示菌,采用杯碟法测定发酵液的热稳定性、酸碱稳定性及光稳定性.结果:拮抗菌发酵液抑菌活性随着温度升高而降低,90℃时抑菌圈直径减至2.70cm,121℃时则无抑菌活性.随着酸碱性增强,抑菌活性均呈逐步下降趋势,但在pH 2.63和pH 10.52下抑菌圈直径仍有3.57cm和3.28cm.紫外光照射4h后,拮抗菌发酵液抑菌圈直径仍有3.13cm.自然光照射9h后,拮抗菌发酵液抑菌活性与对照无显著差异.结论:番茄早疫病菌拮抗菌ZJNU27发酵液具有较强的热稳定性、酸碱稳定性和光稳定性,具有一定开发价值和应用前景.     

两株生防荧光假单胞杆菌的室内筛选试验

从番茄根际土壤中筛选出11株对水稻稻瘟病菌具拮抗活性的细菌原始菌株,其发酵滤液对稻瘟菌菌丝生长抑制率达50％以上的菌株有8个。依据拮抗活性测定结果,确定AbⅢ745和AbⅢ763的单胞分离后代AbⅢ745-6和AbⅢ763-1为最优菌株,其对稻瘟病菌的抑制率分别达96.88％和78.57％,对小麦全蚀病菌、小麦根腐病菌及番茄早疫病菌也有一定的抑制作用。经初步鉴定,AhⅢ745-6和AbⅢ763-1属于假单胞菌科荧光假单胞杆菌。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.