About the origin of European spelt (<Emphasis Type="Italic">Triticum spelta</Emphasis> L.): allelic differentiation of the HMW Glutenin B1-1 and A1-2 subunit genes

To investigate the origin of European spelt (Triticum spelta L., genome AABBDD) and its relation to bread wheat (Triticum aestivum L., AABBDD), we analysed an approximately 1-kb sequence, including a part of the promoter and the coding region, of the high-molecular-weight (HMW) glutenin B1-1 and A1-2 subunit genes in 58 accessions of hexa- and tetraploid wheat from different geographical regions. Six Glu-B1-1 and five Glu-A1-2 alleles were identified based on 21 and 19 informative sites, respectively, which suggests a polyphyletic origin of the A- and B-genomes of hexaploid wheat. In both genes, a group of alleles clustered in a distinct, so-called beta subclade. High frequencies of alleles from the Glu-B1-1 and Glu-A1-2 beta subclades differentiated European spelt from Asian spelt and bread wheat. This indicates different origins of European and Asian spelt, and that European spelt does not derive from the hulled progenitors of bread wheat. The conjoint differentiation of alleles of the A- and B-genome in European spelt suggests the introgression of a tetraploid wheat into free-threshing hexaploid wheat as the origin of European spelt.Electronic Supplementary Material Supplementary material is available in the online version of this article at Communicated by J. Dvorak     

Multilocus phylogeography of the European ground squirrel: cryptic interglacial refugia of continental climate in Europe

The theory of classical and cryptic Pleistocene refugia is based mainly on historical changes in temperature, and the refugia are usually defined within a latitudinal gradient. However, the gradient of oceanic–continental climate (i.e. longitudinal) was also significantly variable during glacial cycles with important biotic consequences. Range‐wide phylogeography of the European ground squirrel (EGS) was used to interpret the evolutionary and palaeogeographical history of the species in Europe and to shed light on its glacial–interglacial dynamic. The EGS is a steppe‐inhabiting species and the westernmost member of the genus in the Palaearctic region. We have analysed 915 specimens throughout the present natural range by employing mitochondrial DNA sequences (cytochrome b gene) and 12 nuclear microsatellite markers. The reconstructed phylogeography divides the species into two main geographical groups, with deep substructuring within both groups. Bulgaria is the centre of the ancestral area, and it also has the highest genetic diversity within the species. The northernmost group of the EGS survived in the southern part of Pannonia throughout several glacial–interglacial cycles. Animals from this population probably repeatedly colonized areas further to the north and west during the glacial periods, while in the interglacial periods, the EGS distribution contracted back to this Pannonian refugium. The EGS thus represents a species with a glacial expansion/interglacial contraction palaeogeographical dynamics, and the Pannonian and southeastern Balkanian steppes are supported as cryptic refugia of continental climate during Pleistocene interglacials.     

Evaluating the Induced-Odour Emission of a Bt Maize and its Attractiveness to Parasitic Wasps

The current discussion on the safety of transgenic crops includes their effects on beneficial insects, such as parasitoids and predators of pest insects. One important plant trait to consider in this context is the emission of volatiles in response to herbivory. Natural enemies use the odours that result from these emissions as cues to locate their herbivorous prey and any significant change in these plant-provided signals may disrupt their search efficiency. There is a need for practical and reliable methods to evaluate transgenic crops for this and other important plant traits. Moreover, it is imperative that such evaluations are done in the context of variability for these traits among conventional genotypes of a crop. For maize and the induction of volatile emissions by caterpillar feeding this variability is known and realistic comparisons can therefore be made. Here we used a six-arm olfactometer that permits the simultaneous collection of volatiles emitted by multiple plants and testing of their attractiveness to insects. With this apparatus we measured the induced odour emissions of Bt maize (Bt11, N4640Bt) and its near-isogenic line (N4640) and the attractiveness of these odours to Cotesia marginiventris and Microplitis rufiventris, two important larval parasitoids of common lepidopteran pests. Both parasitoid species were strongly attracted to induced maize odour and neither wasp distinguished between the odours of the transgenic and the isogenic line. Also wasps that had previously experienced one of the odours during a successful oviposition divided their choices equally between the two odours. However, chemical analyses of collected odours revealed significant quantitative differences. The same 11 compounds dominated the blends of both genotypes, but the isogenic line released a larger amount of most of these. These differences may be due to altered resource allocation in the transgenic line, but it had no measurable effect on the wasps’ behaviour. All compounds identified here had been previously reported for maize and the differential quantities in which they were released fall well within the range of variability observed for other maize genotypes.     

A new multiplex PCR test for the determination of Vrn-B1 alleles in bread wheat (Triticum aestivum L.)

Winter wheat requires vernalization, a long exposure to low but non-freezing temperatures, to promote reproductive development. The vernalization requirement in bread wheat (Triticum aestivum L.) is mainly controlled by the Vrn-1 genes that are located on chromosomes 5A, 5B and 5D. Dominant alleles confer spring habit and are epistatic to the recessive winter alleles which means that spring varieties carry at least one dominant allele. To date, two dominant and one recessive Vrn-B1 alleles have been described. Vrn-B1a (formerly designated as Vrn-B1) differs from the winter vrn-B1 allele by a large deletion in intron 1. Vrn-B1b has an additional small deletion and is probably derived from Vrn-B1a. The novel allele described here and designated as Vrn-B1c also has a large deletion within intron 1 but with different breakpoints from Vrn-B1a or b, and sequence duplication, showing that this is an independently derived spring allele. By combining an exon 1 primer with previously published PCR primers it was possible to develop a multiplex PCR that distinguished all four alleles simultaneously. The multiplex PCR was validated by testing 320 winter wheat and 137 spring wheat varieties. This demonstrated that the novel Vrn-B1c allele was present in 25 spring varieties of diverse origin, showing this allele to be widely distributed.     

Interactive effects of protein and carbohydrates on production of microbial metabolites in the large intestine of growing pigs

The study aimed at determining the effect of protein type and indigestible carbohydrates on the concentration of microbial metabolites in the large intestine of pigs. The experiment involved 36 pigs (15 kg initial body weight) divided into six groups, fed cereal-based diets with highly digestible casein (CAS) or potato protein concentrate (PPC) of lower ileal digestibility. Each diet was supplemented with cellulose, raw potato starch or pectin. After 2 weeks of feeding, pigs were sacrificed and samples of caecal and ascending, transverse and descending colon digesta were collected for analyses of microbial metabolites. PPC increased the concentration of ammonia, p-cresol, indole, n-butyrate, isovalerate and most of the amines in comparison with CAS. Pectin reduced the production of p-cresol, indole, phenylethylamine and isovalerate in the large intestine compared with potato starch. Starch and pectin increased mainly the concentration of n-butyrate and n-valerate in the colon compared to cellulose. Interaction affected mainly amines. Feeding PPC diet with potato starch considerably increased putrescine, cadaverine, tyramine and total amines concentrations compared with PPC diets with pectin and cellulose, whereas feeding CAS diet with starch reduced their concentrations. There was also a significant effect of interaction between diet and intestinal segment on microbial metabolites. In conclusion, PPC intensifies proteolysis in the large intestine and also n-butyrate production. Raw starch and pectin similarly increase n-butyrate concentration but pectin inhibits proteolysis more efficiently than starch. The interactive effects of both factors indicate that pectin and cellulose may beneficially affect fermentative processes in case of greater protein flow to the large intestine.     

Post-translational modifications and multiple tubulin isoforms in Nicotiana tabacum L. cells

Distribution of post-translationally modified tubulins in cells of Nicotiana tabacum L. was analysed using a panel of specific antibodies. Polyglutamylated, tyrosinated, nontyrosinated, acetylated and Δ2-tubulin variants were detected on α-tubulin subunits; polyglutamylation was also found on β-tubulin subunits. Modified tubulins were detected by immunofluorescence microscopy in interphase microtubules, preprophase bands, mitotic spindles as well as in phragmoplasts. They were, however, located differently in the various microtubule structures. The antibodies against tyrosinated, acetylated and polyglutamylated tubulins gave uniform staining along all microtubules, while antibodies against nontyrosinated and Δ2-tubulin provided dot-like staining of interphase microtubules. Additionally, immunoreactivity of antibodies against acetylated and Δ2-tubulins was strong in the pole regions of mitotic spindles. High-resolution isoelectric focusing revealed 22 tubulin charge variants in N. tabacum suspension cells. Immunoblotting with antibodies TU-01 and TU-06 against conserved antigenic determinants of α- and β-tubulin molecules, respectively, revealed that 11 isoforms belonged to the α-subunit and 11 isoforms to the β-subunit. Whereas antibodies against polyglutamylated, tyrosinated and acetylated tubulins reacted with several α-tubulin isoforms, antibodies against nontyrosinated and Δ2-tubulin reacted with only one. The combined data demonstrate that plant tubulin is extensively post-translationally modified and that these modifications participate in the generation of plant tubulin polymorphism. Received: 2 May 1996 / Accepted: 16 September 1996