			Home About us Contact

Germplasm Groups (germplasm + groups)

Distribution by Scientific Domains

Life Sciences	80%

Selected Abstracts

Tall Fescue Adaptation to Low Nitrogen Fertilization in Relation to Germplasm Type and Endophyte Infection

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2008
L. Pecetti
Abstract Efficient crop growth with low nitrogen (N) application is becoming a requirement to face the concern on excessive N emission to the environment and the increasing cost of fertilizers. This study compared six natural populations and three improved varieties of tall fescue (Festuca arundinacea Schreb.) for dry-matter yield over 4 years under ordinary N fertilization (450 kg ha,1 in the 4 years) and very low N fertilization (only 40 kg ha,1 prior to sowing). Both endophyte-infected (EI) and endophyte-free (EF) forms of each accession were sown. On average, ordinary fertilization implied 30 % higher yield than very low fertilization and the EI germplasm outyielded the corresponding EF germplasm (+4.4 %). Mean yield of improved varieties was higher than that of natural populations under ordinary fertilization (P < 0.05), whereas the two germplasm groups did not differ under very low fertilization. Accession × N fertilization interaction was found among natural populations but not among varieties (P < 0.05). A few natural populations were top-yielding under very low fertilization and may be exploited, possibly in combination with endophyte infection, to select tall fescue varieties with enhanced performance under limited N application. [source]

Viability and bar expression are negatively correlated in Oregon Wolfe Barley Dominant hybrids

PLANT BIOTECHNOLOGY JOURNAL, Issue 3 2007
Phil Bregitzer
Summary The expression level of bar, which encodes phosphinothricin acetyltransferase (PAT), was correlated with the inviability of barley hybrids between 20 Golden Promise-derived transgenic lines (Ds-bar lines) and a specialized genetic marker stock, Oregon Wolfe Barley Dominant (OWBD). Each Ds-bar line was homozygous for a modified maize Ds element that encoded bar and that had been delivered via transposition to a unique location. All Ds-bar lines were viable and morphologically similar. Only four of the 20 hybrid populations were viable. The remaining populations died prior to producing seed. Phenotypic, enzyme-linked immunosorbent assay and quantitative reverse transcriptase-polymerase chain reaction analyses of these lines, and of lines from unrelated transformation events that also expressed bar, showed that viability was negatively correlated with bar expression. Analysis of crosses of a high- bar -expressing line with the OWB mapping population showed that the sensitivity of OWBD to PAT segregated as a single locus on chromosome 6HL. No sensitivity to PAT could be detected in several other lines and cultivars. OWBD has been shown to be genetically divergent from other germplasm groups within cultivated barley; therefore, the observed sensitivity may be peculiar to OWBD and thus would not impact generally on the utility of bar as a selectable marker or source of herbicide resistance in barley. Nevertheless, these results demonstrate the extent of allelic variability present in Hordeum vulgare, and suggest an additional variable for consideration when devising protocols for the transformation of Hordeum cultivars or landraces that are not known to be tolerant to PAT. [source]

Consequences of a decentralized participatory barley breeding programme on changes in SSR allele frequency and diversity in one cycle of selection

PLANT BREEDING, Issue 5 2007
F. Fufa
Abstract Changes in allele type, allele frequency and genetic diversity because of selection by individual farmers and breeders were assessed using simple sequence repeats (SSRs) during one cycle of selection in a decentralized participatory barley breeding programme. Selection by both breeders and farmers resulted in the loss of a number of alleles in the majority of the locations, with more alleles lost in the heterogeneous breeding materials than in the fixed genotypes, indicating selection against undesirable traits uncovered in the heterogeneous breeding materials that are presumably linked to SSR alleles. After selection, significant allelic frequency changes were observed at several loci in both the germplasm groups. As the selection was conducted independently in each location, an allele had a chance of being selected in more than one location, and therefore considering the whole study area the allelic composition and diversity of the original genetic materials was maintained after the selection. The study showed the importance of decentralized participatory plant breeding in maintaining genetic diversity that helps stabilize and sustain production in unpredictable production conditions. [source]

Heritability of morphophysiological traits and inbreeding effects in grazing-type lucerne

PLANT BREEDING, Issue 2 2005
L. Pecetti
Abstract To estimate heritability and inbreeding in grazing-type lucerne, 14 parent genotypes and their half-sib and selfed progeny were grown under spaced-plant conditions. Dry-matter weight (four cuts), plant height, basal plant diameter, stem density, and late-autumn vegetation were recorded on a plant basis. Genetic coefficients of variation for the three germplasm groups, and broad-sense heritability on a plot basis for parents were computed from variance component estimates; narrow-sense heritability was estimated from progeny-parent regression. Genetic variation was generally greater among selfed than half-sib progeny. Broad-sense heritability was high, while narrow-sense heritability was much lower for all traits except plant diameter. Inbreeding effects, assessed with comparison between parents and selfed progeny, were notable for plant weight and late-autumn vegetation only. The high correlation coefficients computed between parents and either progeny suggested the equivalent value of self- and polycross-progeny tests for selecting superior parents. [source]

Interspecies and intergenus transferability of barley and wheat D-genome microsatellite markers

ANNALS OF APPLIED BIOLOGY, Issue 3 2010
A. Castillo
A selection of 147 wheat D-genome and 130 barley genomic simple sequence repeat (gSSR) markers were screened for their utility in Hordeum chilense, as an alien donor genome for cereal breeding. Fifty-eight wheat D-genome and 71 barley PCR primer pairs consistently amplified products from H. chilense. Nineteen wheat D-genome and 20 barley gSSR markers were polymorphic and allowed wide genome coverage of the H. chilense genome. Twenty-three of the wheat D-genome and 11 barley PCR primer pairs were suitable for studying the introgressions of H. chilense into wheat, amplifying H. chilense products of distinct size. In 88% of the markers tested, H. chilense products were maintained in the expected homeologous linkage group, as revealed by the analysis of wheat/H. chilense addition lines. Twenty-nine microsatellite markers (eight gSSRs and 21 expressed sequence tags-SSRs) uniformly distributed across the genome were tested for their utility in genetic diversity analysis within the species. Three genetic clusters are reported, in accordance with previous morphological and amplified fragment length polymorphism data. These results show that it is possible to discriminate the three previously established germplasm groups with microsatellite markers. The reported markers represent a valuable resource for the genetic characterisation of H. chilense, for the analysis of its genetic variability, and as a tool for wheat introgression. This is the first intraspecific study in a collection of H. chilense germplasm using microsatellite markers. [source]