RT—PCR检测南方菜豆花叶病毒

根据南方菜豆花叶病毒（ＳＢＭＶ）两株系Ｂ和Ｃ的核酸序列设计两对引物，利用ＲＴ－ＰＣＲ可以特异地区分纯化的和０．２ｇ病叶中的两株系，ＲＴ－ＰＣＲ检测ＳＢＭＶ－Ｂ的灵敏度为１０ｐｇ。     

2002-2004年国家大豆区试品种对大豆花叶病毒抗性的评价

在接种东北大豆产区SMV主要株系N1、N3和黄淮与南方大豆产区SMV株系Sa、SC3条件下,对最新育成的参加2002-2004年国家大豆区试的134个大豆品种进行了抗性评价,结果表明:接种4个株系后,分别有13个品种(东农L13、汾豆56、汾豆60、汾豆61、晋大74、K丰52-1、航天2号、辽03-20、辽95025-5-4、中作2-29、中豆32、科9208、油春32)和5个品种(铁95025-5-5、铁94037-6、汾豆69、冀99、冀鉴27)分别对4个株系和3个株系表现抗侵染,中黄4、中作016、吉林2001-14等25个品种对1-2个株系表现抗侵染;5个品种(公交03-1212、冀鉴37、秦豆9、淮02-02、滑豆20)对4个株系表现抗扩展.以上品种除可用于生产外,还可作为抗SMV育种的抗源.该批参试品种中,黄淮地区品种的平均病情指数最轻,其次是东北地区品种,然后长江流域,华南地区品种的病情最重.从不同类型品种的病情分析,按黄淮夏大豆、北方春大豆、南方夏大豆、南方春大豆、菜用大豆、热带多熟制大豆的顺序逐步加重.在田间条件下,免疫品种数量不多,占参试品种的7.9%,严重度为1级的高抗品种占47.5%,未发现严重度为4级的高感品种,表明多数品种田间抗性较好.     

低温胁迫对黄瓜花叶病毒CMV-BG株系cp基因多态性的影响

研究了低温胁迫下黄瓜花叶病毒与三生烟互作后CMV cp基因序列的变化规律,并分析了植物RNA病毒的进化机制。用黄瓜花叶病毒北京甘蓝分离物(CMV-BG)侵染三生烟不同单株,置于不同温度条件下(常温和低温)培养30 d后,对CMV cp基因进行克隆、序列测定和多态性分析。结果表明,侵染低温组植物CMV的cp基因多态性(Pi=0.001 76)高于常温组(Pi=0.001 14),IFEL分析检测到低温组第48个氨基酸位点为正选择位点,初步表明低温胁迫有助于提高CMV-BG cp基因序列的多态性,温度胁迫是植物RNA病毒与宿主互作过程中基因序列变异的一种重要的作用力。     

Cytochrome P-based resistance mechanism and pyrethroid resistance in the field Anopheles albimanus resistance management trial

The relative rates of cytochrome P⁴⁵⁰ selection in southern Mexican Anopheles albimanus populations were investigated during a 3 years indoor residual house spraying intervention with a pyrethroid (PYR) or DDT, a mosaic of organophosphate (OP)-PYR, and the annual rotation of OP-PYR-carbamate (CARB). This insecticide resistance mechanism, initially evenly spread in the mosquito population, correlated with PYR resistance during the second treated year, when cytochrome P⁴⁵⁰ contents increased in most villages of the PYR, rotation and mosaic schemes. However, by the third year, mean cytochrome P⁴⁵⁰ contents declined to susceptible levels in mosquitoes of the rotation and one mosaic group but not in the PYR-treated villages. In DDT-treated villages, a continuous decrement of cytochrome P⁴⁵⁰ levels occurred since the first treatment year, and susceptible levels were observed at the end of the intervention. Most correlations of cytochrome P⁴⁵⁰ levels and PYR resistance were lost during the third year, indicating that another mechanism evolved in resistant mosquito populations.     

东北亚四国（地区）SMV株系毒力比较

将我国，韩国，日本及俄罗斯远东地区的ＳＭＶ株系与鉴别寄主交互接种测定其毒力。结果指出采用外国的株系鉴别寄坟难以区分我国株系毒力。同样，用我国鉴别寄坟也难以区分外国毒株的毒力，所测定的我国９个株系的１３个代表毒株全部能侵染最抗病的鉴别寄主韩国的Ｂｕｆｆａｌｏ和日本的Ｈａｒｏｊｏｙ。     

Novel pathotypes of lettuce mosaic virus — breakdown of a durable resistance?

Summary Resistance to lettuce mosaic virus (LMV) is derived either from cv. Gallega (g gene) or the wild accession PI251245 (mo gene). Previous studies indicated that these two genes were identical. Breeders in Europe produced numerous resistant cultivars utilisingg while in the USAmo was used. The resistance has been effective for over 20 years. However, recently there have been reports of LMV isolates causing unusually severe and sometimes necrotic symptoms on cultivars with these resistance genes. Investigations of these severe isolates have distinguished three new pathotypes in addition to the common pathotype (II) and identified a novel dominant gene for resistance. Themo/g genes confer resistance to pathotypes I and II but pathotype III possesses virulence for cultivars withg but not for those withmo. These two genes are therefore not identical but are probably either closely linked genes or alleles. Pathotype IV possesses virulence for all lettuce lines so far tested. Some isolates of this pathotype are seed transmitted in cultivars possessingmo org and have caused severe crop losses in southern France. The durability of the resistance conditioned by these two genes is discussed.     

Pyramiding genes for resistance to bean common mosaic virus

Summary Gene pyramiding in Phaseolus vulgaris is being utilized to develop more effective resistance to the temperature-insensitive-necrosis-inducing (TINI) strains of Bean Common Mosaic Virus (BCMV) present in the USA. Our data indicate that contrary to previous work, the bc-3 gene is effective against these strains in the absence of the strain unspecific bc-u gene in genotypes possessing the I gene. The epistatic bc-3 gene interferes with traditional efforts to pyramid the other recessive resistance genes by masking their activity. Indirect selection based on markers linked to the other recessive resistance genes would likewise be ineffective without the ability to also select for the bc-u gene which is required for expression of the bc-2 ² gene in germplasm carrying the I gene. Because the most resistant genotype (I, bc-u, bc-I ², bc-2², bc-3) can only be introduced into a wide range of germplasm through the use of molecular markers linked to the different resistance genes, the search for a marker linked to the strain unspecific bc-u gene should also be given priority.     

Determination of a common forest life cycle assessment method for biodiversity evaluation

Forest biodiversity is highly linked with the occurrence of certain forest development phases (fdp) within the forest life cycle. Generally, the disintegration phase provides the highest biodiversity. The objective of the study was to test different existing forest life cycle assessment approaches aiming at developing a common reliable fdp assessment method. We tested and compared three approaches to record fdp in beech, mixed beech and spruce forests, in managed and unmanaged forests, and in four different plot sizes ranging from 125 to 2000 m². The main results of the fdp comparison are as follows:

(1)

In approximately two thirds of the cases the three considered methods did not yield a corresponding fdp record.

(2)

Generally, the larger the plot sizes, the larger the average fdp deviation in forest reserves.

(3)

The fdp deviation is stronger in beech or spruce dominated forest reserves than in mixed beech forest reserves.

(4)

Plots of 500 m² show most distinct numbers of microhabitats corresponding to the fdp sequence within the forest life cycle.

(5)

Furthermore, the managed forests mostly show lower fdp deviation than the forest reserves.

One approach resulted in the most differentiated portrayal of the studied forest structures compared to the other two as shown by the facts that, (a) the studied forests are seen to be divided up into more fdp than when applying the other two methods, and that (b) the dominant fdp changed depending on the forest community and plot size reflecting different growth conditions and probabilities to meet large dimensioned trees during records, respectively, and (c) considering the distribution of microhabitats which are crucial for xylobiontic (saproxylic) organisms, this approach resulted in the assumed biodiversity patterns with increasing microhabitat numbers up to the disintegration phase thus it was used as a basis for the creation of an optimized fdp assessment method as a tool for common and standardized use in forest ecology and biodiversity research.