Relationships between rhizoplane and rhizosphere bacteria and verticillium wilt resistance in potato

Six cultivars and breeding lines of potato (Solanum tuberosum) differing in susceptibility to verticillium wilt caused by Verticillium dahliae were studied with respect to quantitative and qualitative differences in the bacterial flora of their soil and rhizosphere-rhizoplane. Although, no association was observed between the types of bacteria that inhabited the soil or roots of wilt resistant and susceptible cultivars, quantitative differences were evident. These differences provide the first direct evidence that potato genotypes can influence bacterial populations. Bacterial populations were 9–25-fold higher on roots than in the adjacent soil. As the plants aged, the total number of rootcolonizing bacteria increased between 15 and 245%. Pseudomonas spp. were the most abundant microbes in the soil and rhizosphere-rhizoplane. The bacteria antagonistic to V. dahliae in vitro were identified as members of the genera Bacillus, Pseudomonas, Flavobacterium, and Gluconobacter. A statistically significant trend was evident toward the association of antagonistic bacteria with the more resistant potato cultivars.     

Application of genetic markers to the discrimination of European Black Poplar (Populus nigra) from American Black Poplar (P. deltoides) and Hybrid Poplars (P. x canadensis) in Switzerland

European Black Poplar (Populus nigra) is considered a rare and endangered tree species because of severe reduction of its natural riverine habitat and potential hybridisation with the related non-indigenous taxa P. deltoides and P. x canadensis. As it is difficult to distinguish these taxa solely based on their morphology, we applied a PCR-based assay with an easy-to-use and robust molecular marker set (cpDNA trnL-trnF/RsaI RFLP, nDNA win3 and nDNA POPX/MspI RFLP) in order to identify pure P. nigra. Different plant tissues could be used for fast and standardised DNA extraction. The application of the three marker types was tested on a number of different Populus taxa, and they were also used for the verification of pure P. nigra in a sample of 304 putative P. nigra individuals from Switzerland. Cross-checking of the DNA data with those using a traditional allozyme approach resulted in complete agreement. The availability of molecular identification methods is an important prerequisite for the conservation of European Black Poplar, because pure, non-introgressed plant material can then be used in restoration projects of European floodplains.     

UV spectra of indoles in strong sulphuric acid

Measurement of the UV spectra in 12·7 M H₂SO₄ at 30° and 70° provides a simple, quantitative and specific method for the identification of variously substituted, naturally occurring plant indoles in μg quantities.     

Target identification of covalently binding drugs by activity-based protein profiling (ABPP)

The characterization of the target proteins of drug molecules has become an important goal in understanding its mode of action and origin of side effects due to off-target binding. This is especially important for covalently binding drugs usually containing electrophilic moieties, which potentially can react with nucleophilic residues found in many proteins. This review gives a comprehensive overview of the use of activity-based protein profiling (ABPP) as an efficient tool for the target identification of covalently binding drugs.     

Identification of proteins encoded in Escherichia coli hydA, hydB and analysis of the hydA locus

The hydB gene of Escherichia coli, which is related with the expression of hydrogenase activity, was cloned into the plasmid (pES1). Using the maxicell protein-labeling method, the molecular weight of hydB gene product was estimated. Comparing between the gene products from the mutant strains and that of the hydB genes cloned strains, the molecular weight of the gene product was 35,000 Mr. Similarly, the molecular weight of the gene product of hydA, which had been previously cloned, was determined by maxicell analysis. The molecular weight of hydA gene product was estimated to be 80,000 Mr. Using deletion analysis and Tn1000 insertional inactivation of hydA's function, the hydA coding region was estimated between 2.2 kb and 2.8 kb in a 3.1 kb EcoRI-MluI fragment on the recombinant plasmid pEH3.     

Synthetic DNA probes for the identification of sibling species in the Anopheles gambiae complex

The cloned DNA sequences pAna1, pAnq1 and pAnm14, which may be used to distinguish between at least five of the six species in the Anopheles gambiae Giles complex of Afrotropical malaria vector mosquitoes, have been sequenced. Each clone was found to possess a series of repeated sequences of 41, 30 and 163 bases respectively. In pAnq1 and pAnm14 the repeats were in direct tandem array, whilst in pAna1 the repetitive sequence was found to be interspersed by 15-17 variable bases. A comparison of a number of copies of each of the repetitive sequences within the three clones enabled the definition of the consensus sequence for each repetitive element. Based on these consensus sequences, three oligonucleotides of 21, 23 and 26 bases were derived from pAna1, pAnq1 and pAnm14 respectively. When tested as probes against DNA dot-blots and squash-blots of mosquito specimens, each oligonucleotide retained the same species-specificity as the original clones from which they were derived. The radioactively labelled oligonucleotides were able to detect as little as 5 ng of target genomic DNA in an overnight autoradiographic exposure. The synthetic DNA probes will form the basis of a simplified system for the field identification of Anopheles gambiae sibling species specimens.     

兰州唐古特白刺根际微生物分离鉴定

【目的】从兰州唐古特白刺根际分离得到对植物有潜在促生效果的功能微生物，为研发相关菌种制剂的研究奠定基础。【方法】通过平板划线法从其根际分离纯化出6株细菌，并对菌株进行形态特征观察、革兰氏染色等一系列生理生化试验。用藜麦检测各菌株的促生功能，并对具有优良促生作用的1个菌株16S rRNA基因进行分子鉴定及基因草图绘制。【结果】根据生化鉴定结果，6株细菌分别属于不动杆菌属(Acinetobacter)、土壤杆菌属(Agrobacterium)、类芽孢杆菌属(Paenibacillus)、芽孢杆菌属(Bacillus)、鞘氨醇单胞菌属(Sphingomonas)和假单胞菌属(Pseudomonas)。其中，16S rRNA基因鉴定BC4属于肠杆菌属(Enterobacter)，具有较好的促生效果。【结论】BC4具有较好的促生效果，为兰州唐古特白刺菌种资源的开发和利用提供了一定的理论依据。     

Abiotic factors modulate post-drought growth resilience of Scots pine plantations and rear-edge Scots pine and oak forests

The proportion of planted forests in the Mediterranean Basin is one of the largest in the world. These plantations are dominated by pine species and present a series of characteristics such as low elevation, high competition or small tree size that make them more vulnerable to droughts. However, quantitative assessments of their post-drought growth resilience in accordance with species, site factors and tree characteristics are lacking. In this study we sampled 164 trees at four forest sites located in the drought-prone Sierra Nevada, southeastern Spain. We compared growth responsiveness to drought in rear-edge planted vs. relic natural Scots pine (Pinus sylvestris) and coexisting Pyrenean oak (Quercus pyrenaica) stands. Our objective was to characterize and compare the different growth responses to drought between species and sites and the effect of the main physiographic factors (altitude, aspect, and slope) on these responses since the influence of these factors on post-drought resistance and resilience has received little attention to date. Our results reveal that the planted pine sites with the lowest mean growth rates displayed greater resistance during drought, and that higher altitude was associated with improved resistance and/or resilience for all species and sites. Natural pine and Pyrenean oak stands were better adapted to the dry climatic conditions of the Mediterranean region where the study was undertaken, displaying greater resistance and/or resilience and lower influence of drought on growth in comparison to stands of planted pines. These results suggest that promoting the conservation of high-elevation pine plantations and enhancing the regeneration of natural pine and oak may improve the resistance and resilience of these drought-prone forest ecosystems.