杨树叶锈病研究

松杨栅锈菌（Melampsora larici-populina）导致的杨树叶锈病是杨树病害中分布最广、危害最大的一种病害,它造成杨树林的材积损失和材质下降,严重制约着杨树商品林和生态林的发展。该文从病原菌的分布和寄主种类、病原菌生理分化、寄主抗锈性及分子标记、防治措施等几方面介绍了杨树叶锈病的研究。     

A Brassica rapa Linkage Map of EST-based SNP Markers for Identification of Candidate Genes Controlling Flowering Time and Leaf Morphological Traits

For identification of genes responsible for varietal differences in flowering time and leaf morphological traits, we constructed a linkage map of Brassica rapa DNA markers including 170 EST-based markers, 12 SSR markers, and 59 BAC sequence-based markers, of which 151 are single nucleotide polymorphism (SNP) markers. By BLASTN, 223 markers were shown to have homologous regions in Arabidopsis thaliana, and these homologous loci covered nearly the whole genome of A. thaliana. Synteny analysis between B. rapa and A. thaliana revealed 33 large syntenic regions. Three quantitative trait loci (QTLs) for flowering time were detected. BrFLC1 and BrFLC2 were linked to the QTLs for bolting time, budding time, and flowering time. Three SNPs in the promoter, which may be the cause of low expression of BrFLC2 in the early-flowering parental line, were identified. For leaf lobe depth and leaf hairiness, one major QTL corresponding to a syntenic region containing GIBBERELLIN 20 OXIDASE 3 and one major QTL containing BrGL1, respectively, were detected. Analysis of nucleotide sequences and expression of these genes suggested possible involvement of these genes in leaf morphological traits.     

Application of microbial source tracking methods in a Gulf of Mexico field setting

Aims:  Microbial water quality and possible human sources of faecal pollution were assessed in a Florida estuary that serves shellfishing and recreational activities.
Methods and Results:  Indicator organisms (IO), including faecal coliforms, Escherichia coli and enterococci, were quantified from marine and river waters, sediments and oysters. Florida recreational water standards were infrequently exceeded (6–10% of samples); however, shellfishing standards were more frequently exceeded (28%). IO concentrations in oysters and overlaying waters were significantly correlated, but oyster and sediment IO concentrations were uncorrelated. The human-associated esp gene of Enterococcus faecium was detected in marine and fresh waters at sites with suspected human sewage contamination. Lagrangian drifters, used to determine the pathways of bacterial transport and deposition, suggested that sediment deposition from the Ochlockonee River contributes to frequent detection of esp at a Gulf of Mexico beach.
Conclusions:  These data indicate that human faecal pollution affects water quality in Wakulla County and that local topography and hydrology play a role in bacterial transport and deposition.
Significance and Impact of the Study:  A combination of IO enumeration, microbial source tracking methods and regional hydrological study can reliably inform regulatory agencies of IO sources, improving risk assessment and pollution mitigation in impaired waters.     

利用RAPD和ISSR标记分析青麻种质遗传多样性

利用RAPD和ISSR分子标记检测来自全国11个省(市)的48份青麻种质资源的遗传多样性,为青麻资源利用和育种提供分子生物学依据.在48份青麻种质资源中,17条RAPD引物扩增出191条带,多态条带比率为87.43%;9条ISSR引物扩增出82条带,多态条带比率为88.89%,扩增产物片段大小都在0.1～3.0kb之间.两种分子标记的结果呈显著正相关(r=0.80).基于UPGMA聚类,野生种和栽培种各自聚为相应的类别.     

Genetic variation of wild and hatchery populations of the catla Indian major carp (Catla catla Hamilton 1822: Cypriniformes, Cyprinidae) revealed by RAPD markers

Genetic variation is a key component for improving a stock through selective breeding programs. Randomly amplified polymorphic DNA (RAPD) markers were used to assess genetic variation in three wild population of the catla carp (Catla catla Hamilton 1822) in the Halda, Jamuna and Padma rivers and one hatchery population in Bangladesh. Five decamer random primers were used to amplify RAPD markers from 30 fish from each population. Thirty of the 55 scorable bands were polymorphic, indicating some degree of genetic variation in all the populations. The proportion of polymorphic loci and gene diversity values reflected a relatively higher level of genetic variation in the Halda population. Sixteen of the 30 polymorphic loci showed a significant (p < 0.05, p < 0.01, p < 0.001) departure from homogeneity and the F(ST) values in the different populations indicated some degree of genetic differentiation in the population pairs. Estimated genetic distances between populations were directly correlated with geographical distances. The unweighted pair group method with averages (UPGMA) dendrogram showed two clusters, the Halda population forming one cluster and the other populations the second cluster. Genetic variation of C. catla is a useful trait for developing a good management strategy for maintaining genetic quality of the species.     

Validation of the occurrence of the American eel Anguilla rostrata (Le Sueur, 1817) in free-draining European inland waters

The screening of 2,735 eels from European waters and aquaculture farms was conducted using mitochondrial Cytochrome b and 16S rRNA gene fragments amplified by polymerase chain reaction. Reaction products were either sequenced directly or subjected to analysis using restriction fragment length polymorphism which resulted in species-specific restriction patterns. Beside the expected European eel, Anguilla anguilla (Linnaeus, 1758), the American eel, Anguilla rostrata (Le Sueur, 1817), was also identified in samples from both aquaculture (N = 40 out of 1,025) and from natural waters (N = 44 out of 1,710). The life stages of American eels identified from several German waters draining to either the Baltic Sea and the North Sea ranged from elver to silver eels. This indicates that stocking with glass eels or elvers must have occurred several times most likely in the period from 1998 to 2002. The application of a fast and precise method for species identification and genetic monitoring of eels delivered for stocking is therefore essential for maintaining the autochthonous species composition in future. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Genetic variability in Brazilian wheat cultivars assessed by microsatellite markers

Wheat (Triticum aestivum) is one of the most important food staples in the south of Brazil. Understanding genetic variability among the assortment of Brazilian wheat is important for breeding. The aim of this work was to molecularly characterize the thirty-six wheat cultivars recommended for various regions of Brazil, and to assess mutual genetic distances, through the use of microsatellite markers. Twenty three polymorphic microsatellite markers (PMM) delineated all 36 of the samples, revealing a total of 74 simple sequence repeat (SSR) alleles, i.e. an average of 3.2 alleles per locus. Polymorphic information content (PIC value) calculated to assess the informativeness of each marker ranged from 0.20 to 0.79, with a mean of 0.49. Genetic distances among the 36 cultivars ranged from 0.10 (between cultivars Ocepar 18 and BRS 207) to 0.88 (between cultivars CD 101 and Fudancep 46), the mean distance being 0.48. Twelve groups were obtained by using the unweighted pair-group method with arithmetic means analysis (UPGMA), and thirteen through the Tocher method. Both methods produced similar clusters, with one to thirteen cultivars per group. The results indicate that these tools may be used to protect intellectual property and for breeding and selection programs.     

Development of 10 polymorphic microsatellite loci primers for Codonopsis pilosula Nannf. (Campanulaceae)

Codonopsis pilosula Nannf., as an important traditional Chinese medicinal plant species, has been used to treat fatigue, thirst and loss of appetite. In this study, we developed 10 new microsatellite loci primers from the genome of this species using the combined biotin capture method. The polymorphism of each locus was further assessed through 27 individuals from four geographically distant populations. The number of alleles per locus ranged from 6 to 11. The observed and expected heterozygosity ranged from 0.15 to 0.24 and 0.27 to 0.40, respectively. We further performed cross-priming tests of these loci in the other three congeneric species. These microsatellite markers will be useful for investigating genetic diversity within and between populations of these species.     

珍稀濒危蕨类植物东方水韭的遗传多样性

采用ISSR分子标记对珍稀濒危蕨类植物东方水韭和中华水韭4个自然居群共72个样品进行了DNA多态性分析。从65个随机引物中筛选出11个有效引物,共产生98条DNA片段,其中68条为多态性条带,多态位点百分率(PPL)为66.33%。东方水韭两个居群的多态位点百分比率(PPL)较低(8.16%和7.14%)。中华水韭两个居群的PPL也较低(9.18%和23.47%)。中华水韭物种水平上的PPL(51.02%)高于东方水韭(9.18%)。AMO-VA分析结果表明,东方水韭遗传变异中主要存在于居群内(94.74%),而中华水韭绝大部分的遗传变异却存在于居群间(86.71%)。东方水韭和中华水韭个体间UPGMA聚类结果表明:同一物种的个体完全能聚在一起,中华水韭的两个居群也能明显分开,而东方水韭两居群的个体并不能完全聚在一起。探讨了可能造成上述居群遗传结构模式的主要因素,同时提出今后工作中需重点解决的问题。     

雅鲁藏布江河谷丝须蒟蒻薯遗传多样性的初步研究

分布于雅鲁藏布江河谷的丝须蒟蒻薯(Taccaintegrifolia)与其在东南亚的主要分布区具有明显的间断分布格局。为了探讨地理隔离对其居群遗传结构和遗传多样性的影响,我们应用ISSR分子标记方法对采自西藏墨脱的3个丝须蒟蒻薯居群共65个个体进行了遗传多样性和居群遗传结构分析,并与马来西亚Seremban的1个居群(19个个体)进行了比较。19个ISSR引物共扩增到165个位点,其中111个为多态位点,占67.68%。丝须蒟蒻薯在物种水平上的遗传多样性虽然不低(PPB=67.68%,HT=0.185,Hsp=0.292),但在居群内的遗传多样性却非常低(PPB=12.81%,HE=0.065,Hpop=0.044)。与马来西亚居群(Ma)(PPB=31.71%)相比,墨脱的3个居群遗传多样性极低(PPB分别为3.66%,8.54%,7.32%)。Ma居群与墨脱居群相隔2000km以上,两个地区间的遗传分化程度很大(GST=0.777,FST=0.9206),而墨脱的3个居群间(0.28%)及居群内(7.94%)的遗传分化却非常低(P<0.001)。居群间极其有限的基因流(Nm=0.1435)可能是由于该物种是以自交为主的种类、种子散布很困难、居群间的隔离、生境的破碎化等原因所致。总之,雅鲁藏布江河谷地区特殊的地形和地貌以及与其他热带地区的地理隔离是造成丝须蒟蒻薯在这一地区遗传多样性极低的可能原因。