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The sensitivity of fluorescence in situ hybridization (FISH) for mapping plant chromosomes of single-copy DNA sequences is limited. We have adapted for plant cytogenetics a new signal-amplification method termed tyramide-FISH (Tyr-FISH). Until present this technique has only been applied to human chromosomes. The method is based on enzymatic deposition of(More)
  Allium fistulosum harbours a number of desirable agronomical traits for the breeding of onions. However exploitation of A. fistulosum for onion breeding via direct sexual hybridization is problematic. Therefore, we examined if a bridge cross, using A. roylei as a bridging species, might provide an alternative. By means of genomic in situ hybridization(More)
Downy mildew resistance originating from Allium roylei Stearn provides a complete resistance to onions and is based on one, dominant gene. Since A. roylei can successfully be hybridized with onion (A. cepa L.), a breeding scheme aimed at the introgression of this gene was initiated ca. 20 years ago. Several setbacks in this programme were encountered,(More)
This paper describes the development of a reliable transformation protocol for onion and shallot (Allium cepa L.) which can be used year-round. It is based on Agrobacterium tumefaciens as a vector, with three-week old callus, induced from mature zygotic embryos, as target tissue. For the development of the protocol a large number of parameters were studied.(More)
Introgression of Allium fistulosum into the genome of A. cepa using A. roylei as a bridging species was studied by means of genomic in situ hybridization (GISH). Here we demonstrate for the first time that A. fistulosum can be stably introgressed into A. cepa with a bridge-cross. The first and second bridge-cross generations were fertile, although pollen(More)
In order to anchor Rosa linkage groups to physical chromosomes, a combination of the Tyramide-FISH technology and the modern molecular marker system based on High Resolution Melting (HRM) is an efficient approach. Although, Tyramide-FISH is a very promising technique for the visualization of short DNA probes, it is very challenging for plant species with(More)
Within the framework of the International Solanaceae Genome Project, the genome of tomato (Solanum lycopersicum) is currently being sequenced. We follow a 'BAC-by-BAC' approach that aims to deliver high-quality sequences of the euchromatin part of the tomato genome. BACs are selected from various libraries of the tomato genome on the basis of markers from(More)
The chromosome preparation is a crucial step for obtaining satisfactory results in molecular cytogenetic researches. The preparation of plant chromosomes for molecular cytogenetic purposes remains a challenge for some species. In contrast to human chromosome preparation, the processes occurring during plant chromosome preparation and causing chromosome(More)
Rosaceae is a family containing many economically important fruit and ornamental species. Although fluorescence in situ hybridization (FISH)-based physical mapping of plant genomes is a valuable tool for map-based cloning, comparative genomics and evolutionary studies, no studies using high resolution physical mapping have been performed in this family.(More)
The level of polymorphism in tomato was studied using ISSR-PCR. Five tomato species: Lycopersicon esculentum, Lycopersicon pennellii, Lycopersicon cheesmanii, Lycopersicon humboldtii, Lycopersicon hirsutum and two Lycopersicon esculentum substitution lines IL 6-3 and WSL 6 were analyzed. ISSR-PCR was performed with fourteen primers. Nine of these fourteen(More)