Isolation of two strains of a new Tombusvirus (Havel river virus, HaRV) from surface waters in Germany

Two virus isolates from water samples — one from a small stream in South Western Germany and another one from the Havel river in North Eastern Germany c. 500 km away, proved to be strains, named S and H, respectively, of a new Tombusvirus for which the name Havel river virus (HaRV) had been suggested previously in a brief account. Immunoelectron microscopical decoration tests and sequence comparisons of the coat proteins indicated that the two HaRV strains are only distantly related to known Tombusviruses. The closest relationships were found to Cucumber necrosis virus. Nothing is known about their natural hosts. Because the S strain of HaRV was isolated in a woody area from a small stream close to its origin, they may be pathogens of trees or wild plants in such habitats.     

辣椒上烟草轻型绿花叶病毒的鉴定

 辣椒源自南美洲,属于茄科辣椒属（Capsicum L.）,为重要经济作物。病毒病是影响辣椒生产的主要病害,侵染辣椒的病毒有40余种［1］,烟草轻型绿花叶病毒（Tobacco mild green mosaic virus, TMGMV）是近年来在辣椒上发生和危害报道较多的病毒之一。TMGMV是McKinney［2］于1935年在烟草属植物（Nicotiana gluanca）上首次发现的,为烟草花叶病毒属（Tobamovirus）成员。除辣椒外,番茄［3］、凤仙花、蓝眼菊和矮牵牛也是TMGMV的自然寄主。     

芋花叶病毒的RT-PCR检测及外壳蛋白基因序列分析

 采用RT-PCR技术对采自中国湖北、浙江和山东的91份芋[Colocasia esculenta（L.）Schott]样品的芋花叶病毒（Dasheen mosaic virus,DsMV）进行了检测,检出率为26.4%。对其中14个DsMV分离物的317 bp扩增产物（为外壳蛋白基因的一部分）序列分析的结果显示,各分离物内的核苷酸变异相对较低,而分离物间存在较大的分子变异,相似性为68.3% ~ 97.8%。对来自湖北和浙江的2个DsMV分离物DsMV-SCS和DsMV-JH的外壳蛋白基因（coat protein gene,cp）进行了测序,全长分别为951 bp和987 bp,二者cp核苷酸和氨基酸序列相似性分别为79.0%和82.3%,与已报道DsMV的cp核苷酸和氨基酸序列相似性分别为73.0% ~ 92.1%和74.8% ~ 98.2%,在构建的系统发育树上聚在两个不同的簇,各DsMV分离物的系统进化关系与其寄主和地理来源无显著相关性。     

Transgene expression for Gladiolus plants grown outdoors and in the greenhouse

Transgene expression was evaluated for Gladiolus plants transformed with either the CaMV 35S, double CaMV 35S, rolD, or Arabidopsis UBQ3 promoter controlling the uidA or bean yellow mosaic virus coat protein gene in either the sense or antisense orientation to determine differences in expression for plants grown in the greenhouse and outdoors for two years. There was more variability in GUS expression when plants were grown outdoors than in the greenhouse for two years. Four of the six transformed plant lines with the UBQ3, rolD, and CaMV 35S promoters grown outdoors showed significant differences in GUS expression from year to year as compared to two of the six lines with the UBQ3 and rolD promoters grown in the greenhouse. When grown the same year, two plant lines with the CaMV 35S and one line with the rolD promoter showed 2–16× higher levels of GUS expression outdoors than in the greenhouse, and one plant line with the UBQ3 promoter had 31× higher GUS expression in the greenhouse instead of outdoors. Three of six plant lines transformed with the bean yellow mosaic virus coat protein gene in either the sense or antisense orientation under control of the double CaMV 35S promoter showed obvious transgene expression as compared to three lines that did not show expression or negligible expression for both years when plants were grown both outdoors and in the greenhouse. This study verified long-term gene expression, rather than silencing, for Gladiolus plants when grown outdoors and in the greenhouse from year to year.     

脱落酸与种皮对杜梨种子休眠与萌发的影响

以当年新采收杜梨种子和自然贮藏1 a种子为试验材料,研究了种皮和不同浓度的脱落酸(ABA)对诱导杜梨种子休眠与萌发的影响.结果表明:杜梨种皮和脱落酸均能够抑制杜梨种子的萌发,种皮的抑制萌发效应显著大于ABA的作用,杜梨种子去除种皮后,休眠性可被部分解除.脱落酸对杜梨种子抑制萌发的效应在去皮和不去皮种子中表现明显差异,5 mg/L ABA浓度对未去皮种子产生明显抑制效应,20 mg/L ABA浓度对去皮种子产生明显抑制效应,说明未去皮种子对ABA的敏感性大于去皮种子.种皮与ABA的双重抑制效应,使种子对ABA浓度水平差异的敏感性增强.不同激素组合试验说明了GA3、6-BA和ABA在杜梨种子休眠与萌发中的作用.     

合肥地区发生的西瓜花叶病的病原鉴定

 从合肥市郊区的西瓜病叶上分离出一病毒分离物,该分离物的热钝化温度为60~65℃,稀释终点为10^-4~10^-5,寄主体外存活期为20~23 d,电镜观察病毒粒子约750 nm×13 nm。参考已发表的小西葫芦黄化花叶病毒(Zucchini yellow mosaic virus,ZYMV) CP基因序列设计引物,RT-PCR扩增得到CP基因片段。将该CP片段克隆到pGEM-3Zf (+)中,测序结果表明,该CP基因全长840 nt,共编码279个氨基酸,与国内报道的ZYMV CP基因的核苷酸序列同源性为83.0%~97.3%,氨基酸序列的同源性为91.8%~99.8%,证明该分离物为ZYMV。     

褐藻酸钠涂膜剂的特性研究

对褐藻酸钠凝胶经冻结和解冻处理后的持水能力、凝胶强度、弹性、韧性及状态变化等特性进行了比较试验。结果表明；褐藻酸钠凝胶的这些性质与凝胶体内的钠和钙的比率直接相关；采用２％的褐藻酸钠溶液与５％的氯化钙溶液凝胶化２ｍｉｎ，所形成的凝胶具有很好的涂膜性能。     

半巢式-RT-Realtime PCR检测李痘病毒

李痘病毒(Plum pox virus,PPV)是我国重要的植物检疫性有害生物。本研究根据PPV中CP基因(coat protein gene)的保守序列,设计了3条PCR引物和1条TaqMan探针,建立了半巢式-RT-RealtimePCR检测PPV的方法。该方法有机地结合了巢式PCR和实时荧光PCR技术;3条引物形成的2套PCR体系相互验证,有效提高了结果的准确性;荧光探针有效提高了检测的灵敏度。实验结果表明,本方法准确、灵敏、简便、快速,检出低限可达37fg/μL植物总RNA。     

Characterization of a New Nepovirus Infecting Apricot in Southeastern France: Apricot Latent Ringspot Virus

A pathogen was transmitted from apricot trees showing symptoms of viral infection to GF305 peach seedlings which reacted by stunting, shortened internodes and chlorotic mottling. The agent was transmitted to cherry, apricot, peach and plum by grafting and to several herbaceous hosts by mechanical inoculation. Isometric nepovirus-like particles of 30–31 nm diameter extracted from infected Chenopodium quinoa sedimented as two peaks in sucrose gradients. These particles contained two single stranded RNAs of approximately 5.9 and 7.9 kb, and a single coat protein subunit of 53.7 kDa. No cross-reactions were observed with a number of nepoviruses infecting fruit trees. Inoculation of purified particles to herbaceous or woody hosts reproduced the same symptoms caused by the original isolate. Sequencing of a 2.2 kbp cDNA clone covering the 3 end of the small genomic RNA identified an open reading frame encoding a 317 aa N-truncated protein exhibiting significant similarities with the coat protein of nepoviruses. The 1257 nt long 3 non-coding region showed up to about 65% homology to the equivalent region of members of the subgroup C of nepoviruses. The properties of this pathogen do not match those of any previously described nepovirus. It should therefore be considered as a new member of the subgroup C of nepoviruses, for which the name of Apricot latent ringspot virus (ALRSV) is proposed.The nucleotide sequence reported in this work has been deposited in the EMBL databank under the accession number AJ278875.     

Ultrastructure of Seed Coat Development in the Natural Tetraploid Trifolium pratense L.

Seed coat development in the natural tetraploid Trifolium pratense L. was studied by electron microscopy. The mature seed coat derived from the outer integument is composed of three layers of cells. The cells of the outer epidermis divide anticlinally and undergo radial elongation to form a macrosclereid layer. The cells are characterized by thin walls, the presence of amyloplasts, and numerous vacuoles which are completely or incompletely filled with tannin. The outer tangential walls are thickened at an early stage. An electron-translucent cap develops in the outer tangential walls of the macrosclereid cells at the globular embryo stage. Osteosclereid cells are highly vacuolate with densely staining cytoplasm. Gradually, extensive intercellular spaces are formed. The parenchyma cells are small and have prominent intercellular air spaces. Maturation eventually leads to the disappearance of cytoplasm in all cells, and the compression of the cells of the parenchyma layer.