马铃薯晚疫病菌分子遗传及与寄主互作研究

近年来马铃薯晚疫病的重新暴发再次引起世界各国极大关注,特别对马铃薯晚疫病菌的分子遗传学的研究,包括病菌基因组遗传、转录和物理图谱的构建,病菌致病的分子机制以及马铃薯-马铃薯晚疫病菌互作分子机制等。本文就近几十年来对马铃薯晚疫病菌在生物学和病理学,分子遗传学等研究方面作简要综述,并对其研究趋势进行了展望。     

分子生物学技术在松材线虫研究中的应用

根据松材线虫(Bursaphlenchus xylophilus)分子生物学的研究基础,以及基于不同的研究目的,对松材线虫不同DNA区域,包括基因组DNA、线粒体DNA、核糖体DNA和卫星DNA研究做了综述,并分析、比较一些常用的分子生物学技术在松材线虫研究中的适用性,以及在生物防治研究中的进展。     

福建马铃薯S病毒的分子鉴定及发生情况

为明确福建省马铃薯S病毒(PVS)的发生与分布情况,对福建省马铃薯主要种植区的PVS进行了鉴定和普查.在利用电镜技术和传统生物学方法鉴定的基础上,克隆了PVS外壳蛋白(cp)基因,依据PVS外壳蛋白氨基酸序列建立了PVS不同分离物的系统进化树.研究表明,利用PVS 外壳蛋白氨基酸序列分析可准确鉴定PVS,同时可分析不同分离物间的分子差异.利用病毒特异性引物和DIG标记的PVS cp基因为探针,分别利用RT-PCR技术和核酸斑点杂交技术(NASH)对PVS进行了检测,并对检测技术进行了改进.调查结果表明,PVS在福建省广泛分布,发病率最高可达80%以上,当地农家自留种可能是田间PVS的主要来源.     

陆地棉对黄萎病抗性的分子标记研究

 利用陆地棉标准系TM-1和常抗棉2个陆地棉品种杂交并自交,获得109个F₂单株及F_2:3家系为作图群体,以SSR、RAPD和SRAP 3种分子标记进行抗黄萎病性状的分子标记筛选。结果从1611对(条)引物中仅筛选到70对(条)多态性引物,获得75个多态性位点并进行标记间的连锁性分析。75个标记构建了一个包括15个连锁群,全长535 cM的陆地棉品种间分子标记遗传连锁图,标记间平均距离为11.15 cM,有27个标记不能进入任何连锁群。连锁群的标记数最少2个,最多6个;长度从1.0 cM到92.7 cM不等。对其F_2:3家系的成株期抗黄萎病性状即平均病情指数的分布进行分析,显示其呈正态分布,进一步说明陆地棉对黄萎病的抗性为数量遗传;单标记分析及复合区间作图,检测出与抗黄萎病性相关的3个QTL,分别位于第3、5、6连锁群上,贡献率分别为14.15%、3.45%和18.78%。另外,对该群体生长过程中黄萎病不同发病高峰期的病情也进行了分析。     

基于分子遗传标记技术的实蝇种群遗传关系研究进展

分子遗传标记技术已用于分析实蝇的种群遗传关系,本文介绍了分子遗传标记技术在实蝇的起源、入侵、定殖、扩散及其他方面的研究进展,首次分析了我国实蝇种群遗传研究的现存问题并针对检疫性实蝇种群遗传关系研究提出了建议.     

猪繁殖与呼吸综合征病毒分子生物学研究进展

猪繁殖与呼吸综合征病毒(PRRSV)是引起猪繁殖与呼吸综合征的病原体,本文对PRRSV的分子生物学研究进展进行了综述,主要包括PRRSV的基因组结构、病毒蛋白及其功能、抗原变异等,旨在为诊断技术、免疫机理研究、疫苗设计与疫病防制提供借鉴.     

Assessment of biological and molecular variability between and within field isolates of Plasmodiophora brassicae

Plasmodiophora brassicae is an obligate biotroph that causes clubroot, one of the most damaging diseases of crucifers. Differential cultivars and random amplified polymorphic DNA markers were used to assess the extent of genetic diversity among nine single-gall populations of P. brassicae and 37 single-spore isolates (SSI) derived from four of those field samples. Isolates were classified into eight pathotypes, and each isolate was associated with a unique molecular genotype. Virulence and DNA polymorphisms were detected within and between field isolates, and among SSIs from different pathotypes, hosts and geographical origins. The relatively high level of genetic diversity among field isolates was similar to that among SSIs derived from a single-club field isolate. Molecular and pathogenicity-based classifications were not clearly correlated, but isolates belonging to pathotype P1 were clustered. Two RAPD markers were specific to pathotype P1. The finding that genetic differences can occur in P. brassicae field isolates will be an important consideration in resistance genetic studies and in choosing breeding strategies to develop durable clubroot resistance.     

抗稻瘿蚊品种多抗1的抗性遗传分析及抗性基因定位

稻瘿蚊是亚洲稻区主要害虫,采用抗虫品种进行防治是最理想的方法。1993～1995年,广东省农科院与国际水稻研究所有关专家紧密合作,对能抗华南4个稻瘿蚊生物型的品种多抗1作进一步抗性遗传分析,确认多抗1对中国稻瘿蚊生物型1和4的抗性受显性单基因控制,这个基因暂定名为GM—6(t)。以多抗1×丰银占1组合的F3代160个家系作基因标记,据DNA库分离个体分析(BSA)原理,用随机扩增多态性DNA(RAPD)标记物OPM6(1.4kb),首次成功地标记了这个抗性基因。随后多态性扩增产物经~(32)p标记,用作探针,检测另一个参考作图群体IR64×Azucena,将这个抗性基因定位在水稻第4条染色体上,位于RG214和RG163两个DNA限制性片段长度多态性(RFLP)标记之间。应用这些分子标记辅助选择有可能不必通过稻瘿蚊的直接筛选,快速准确地选育抗稻瘿蚊品种或进行抗性基因累加。     

Characterization of a pothos (Scindapsus aureus) virus with unusual properties

A virus for which the name of pothos latent virus (PoLV) is proposed, was isolated by inoculation of sap from symptomless plants ofScindapsus aureus. PoLV had isometric particlesc. 30 nm in diameter, a monopartite genome consisting of a non polyadenylated, single-stranded RNA moleculec. 4,300 nucleotides in length, constitutingc. 17% of the particle weight, and a single type of coat protein subunit with aM _r ofc. 40,000 Daltons. The biological properties (host range reactions) of PoLV resembled those ofTombusviridae for it infected most of the artificial hosts locally, inducing symptoms recalling those elicited by several species of the above family. Like tombus- and carmoviruses, PoLV had two subgenomic RNAs which, however, differed in size from those of both genera. The dsRNA pattern was also distinctly different. Cytopathological features recalled those of tombusviruses except for the lack of multivesicular inclusion bodies. PoLV was serologically related to, but distinct from twoCarmovirus (i.e., galinsoga mosaic and Ahlum waterborne viruses) and threeTombusvirus species (i.e. eggplant mottled crinkle, Sikte waterborne and Lato river viruses). Thus, PoLV had properties somewhat intermediate between those ofTombusvirus andCarmovirus genera but bridged the two taxa through the serological relationship with some of their species. The taxonomic position of PoLV is still undetermined. It must await the results of molecular investigations now underway.     

Leek Proliferation: A New Phytoplasma Disease in the Czech Republic and Italy

During the summer 1996, twelve of twenty-eight leek plants located in a garden near eské Budjovice, South Bohemia exhibited symptoms typical of diseases associated with phytoplasmas. In summer 1998 similar symptoms were detected in leek plants in a field used for seed production located in Romagna, North Italy. In both cases the plants were established in the spring of the previous year. Plants showed flower abnormalities: stamen elongation, anther sterility, pistil proliferation, as well as poor, if any, seed production. Phytoplasma-like structures were detected by scanning and transmission electron microscopy in phloem sieve elements in the Czech diseased plants, but not in healthy ones. Nested-PCR amplifications of extracted DNA with phytoplasma-specific oligonucleotide primer pairs confirmed the presence of phytoplasmas in these plants at low concentrations. Restriction fragment length polymorphism analyses of amplified ribosomal sequences allowed the identification of detected phytoplasmas: all the samples from the Czech Republic contained aster yellows related phytoplasmas (16SrI-B) while in the Italian samples aster yellows related phytoplasmas (16SrI-B) together with stolbur related phytoplasmas (16SrXII-A) were identified. This is the first report of detection and identification of a phytoplasma disease of leek in the Czech Republic and Italy.