Targeted generation of polyploids in Hydrangea macrophylla through cross-based breeding.

Background: Up to now, diploid and triploid cultivars were reported for the ornamental crop Hydrangea macrophylla. Especially, the origin of triploids and their crossing behaviors are unknown, but the underlying mechanisms are highly relevant for breeding polyploids.

Results: By screening a cultivar collection, we identified diploid, triploid, tetraploid and even aneuploid H.

Molecular Reconstruction of an Old Pedigree of Diploid and Triploid Genotypes.

The ornamental crop species exhibits diploid and triploid levels of ploidy and develops lacecap (wild type) or mophead inflorescences. In order to characterize a germplasm collection, we determined the inflorescence type and the 2C DNA content of 120 plants representing 43 cultivars. We identified 78 putative diploid and 39 putative triploid plants by flow cytometry.

"The usual suspects"- analysis of transcriptome sequences reveals deviating B gene activity in C. vulgaris bud bloomers.

Background: The production of heather (Calluna vulgaris) in Germany is highly dependent on cultivars with mutated flower morphology, the so-called diplocalyx bud bloomers. So far, this unique flower type of C. vulgaris has not been reported in any other plant species.

AFLP-based genetic mapping of the "bud-flowering" trait in heather (Calluna vulgaris).

Background: Calluna vulgaris is one of the most important landscaping plants produced in Germany. Its enormous economic success is due to the prolonged flower attractiveness of mutants in flower morphology, the so-called bud-bloomers. In this study, we present the first genetic linkage map of C.

Malformation of gynoecia impedes fertilisation in bud-flowering Calluna vulgaris.

In Calluna vulgaris, a common bedding plant during autumn in the northern hemisphere, the bud-blooming mutation of flower morphology is of high economic importance. Breeding of new bud-blooming cultivars suffers from poor seed set in some of the desirable bud-flowering crossing partners. In the current study, fertilisation and seed development in genotypes with good or poor seed set were monitored in detail in order to examine pre- and post-zygotic cross breeding incompatibilities.

Large impact of the apoplast on somatic embryogenesis in Cyclamen persicum offers possibilities for improved developmental control in vitro.

Background: Clonal propagation is highly desired especially for valuable horticultural crops. The method with the potentially highest multiplication rate is regeneration via somatic embryogenesis. However, this mode of propagation is often hampered by the occurrence of developmental aberrations and non-embryogenic callus.

'Who's who' in two different flower types of Calluna vulgaris (Ericaceae): morphological and molecular analyses of flower organ identity.

Background: The ornamental crop Calluna vulgaris is of increasing importance to the horticultural industry in the northern hemisphere due to a flower organ mutation: the flowers of the 'bud-flowering' phenotype remain closed i.e. as buds throughout the total flowering period and thereby maintain more colorful flowers for a longer period of time than the wild-type.

Implementation of a model for identifying Essentially Derived Varieties in vegetatively propagated Calluna vulgaris varieties.

Background: Variety protection is of high relevance for the horticultural community and juridical cases have become more frequent in a globalized economy due to essential derivation of varieties. This applies equally to Calluna vulgaris, a vegetatively propagated species from the Ericaceae family that belongs to the top-selling pot plants in Europe. We therefore analyzed the genetic diversity of 74 selected varieties and genotypes of C.

Comparative analysis of cell cycle events in zygotic and somatic embryos of Cyclamen persicum indicates strong resemblance of somatic embryos to recalcitrant seeds.

Embryo development and germination of Cyclamen persicum have been comparatively characterized for zygotic and somatic embryos with regard to mitotic activity and morphology in order to identify developmental abnormalities in somatic embryogenesis. Zygotic embryo development proved to be highly synchronous with distinct periods of cell division, cell elongation and embryo maturation within a total period of 17 weeks of seed development. Somatic embryo development was accomplished within only 3 weeks, resulting in a mixture of morphologically highly variable embryos.

Large-scale analysis of 73 329 physcomitrella plants transformed with different gene disruption libraries: production parameters and mutant phenotypes.

Gene targeting in the moss Physcomitrella patens has created a new platform for plant functional genomics. We produced a mutant collection of 73 329 Physcomitrella plants and evaluated the phenotype of each transformant in comparison to wild type Physcomitrella. Production parameters and morphological changes in 16 categories, such as plant structure, colour, coverage with gametophores, cell shape, etc.

From axenic spore germination to molecular farming. One century of bryophyte in vitro culture.

The first bryophyte tissue culture techniques were established almost a century ago. All of the techniques that have been developed for tissue culture of seed plants have also been adapted for bryophytes, and these range from mere axenic culture to molecular farming. However, specific characteristics of bryophyte biology--for example, a unique regeneration capacity--have also resulted in the development of methodologies and techniques different than those used for seed plants.

An improved and highly standardised transformation procedure allows efficient production of single and multiple targeted gene-knockouts in a moss, Physcomitrella patens.

The moss Physcomitrella patens is the only land plant known to date with highly efficient homologous recombination in its nuclear DNA, making it a unique model for plant functional genomics approaches. For high-throughput production of knockout plants, a robust transformation system based on polyethylene glycol-mediated transfection of protoplasts was developed and optimised. Both the DNA conformation and pre-culture of plants used for protoplast isolation significantly affected transformation efficiencies.

A tool for understanding homologous recombination in plants.

Attempts for establishing an efficient gene targeting (GT) system in seed plants have hitherto not been successful. In contrast, GT based on homologous recombination is highly efficient in Physcomitrella, making this moss a novel tool in reverse genetics. However, why homologous and illegitimate recombination are differently regulated between Physcomitrella and seed plants is still enigmatic.

Effects of nutrients, cell density and culture techniques on protoplast regeneration and early protonema development in a moss, Physcomitrella patens.

To regenerate auxotrophic mutants of Physcomitrella patens, two media of increasing complexity were developed. The survival rate of protoplasts was around 30% higher on full medium when compared to standard minimal medium. Protoplast survival was higher in a medium containing 2.

High frequency of phenotypic deviations in Physcomitrella patens plants transformed with a gene-disruption library.

Background: The moss Physcomitrella patens is an attractive model system for plant biology and functional genome analysis. It shares many biological features with higher plants but has the unique advantage of an efficient homologous recombination system for its nuclear DNA. This allows precise genetic manipulations and targeted knockouts to study gene function, an approach that due to the very low frequency of targeted recombination events is not routinely possible in any higher plant.