Cytogenetics for the model system Arabidopsis thaliana

Abstract

SummaryA detailed karyotype of Arabidopsis thaliana is presented using meiotic pachytene cells in combination with fluorescence in situ hybridization. The lengths of the five pachytene bivalents varied between 50 and 80 µm, which is 20-25 times longer than mitotic metaphase chromosomes. The analysis confirms that the two longest chromosomes (1 and 5) are metacentric and the two shortest chromosomes (2 and 4) are acrocentric and carry NORs subterminally in their short arms, while chromosome 3 is submetacentric and medium sized. Detailed mapping of the centromere position further revealed that the length variation between the pachytene bivalents comes from the short arms. Individual chromosomes were unambiguously identified by their combinations of relative lengths, armratios, presence of NOR knobs and FISH signals with a 5S rDNA probe and chromosome specific DNA probes. Polymorphisms were found among six ecotypes with respect to the number and map positions of 5S rDNA loci. All ecotypes contain 5S rDNA in the short arms of chromosomes 4 and 5. Three different patterns were observed regarding the presence and position of a 5S rDNA locus on chromosome 3. Repetitive DNA clones enabled us to subdivide the pericentromeric heterochromatin into a central domain, characterized by pAL1 and 106B repeats, which accommodate the functional centromere and two flanking domains, characterized by the 17 A20 repeat sequences. The upper flanking domains of chromosomes 4 and 5, and in some ecotypes also

Analysis of the 5S RNA Pool in Arabidopsis thaliana: RNAs Are Heterogeneous and Only Two of the Genomic 5S Loci Produce Mature 5S RNA

“…The Arabidopsis thaliana Columbia ecotype possesses 5S rDNA loci in the pericentromeric region of chromosomes 3, 4, and 5 (Murata et al 1997;Camilleri et al 1998;Fransz et al 1998;Schmidt et al 1995;Tutois et al 1999 and Fig. 1) for a total of ∼1000 5S rDNA genes.…”

“…Arabidopsis thaliana is known to contain ∼1000 copies of 5S rDNA per haploid genome, and these occur in tandem arrays (Campell et al, 1992) localized in the pericentromeric heterochromatin of chromosomes 3, 4, and 5 (with a major locus on the left arm and a minor locus on the right arm of chromosome 5) in the Columbia ecotype (Murata et al 1997;Fransz et al 1998). In Arabidopsis thaliana, two types of 5S rDNA repeated units exist: the major variant with 0.5-kb repeats and one with short repeats (251 bp).…”

Molecular cytogenetic mapping of Cucumis sativus and C. melo using highly repetitive DNA sequences

“…For pollen mother cell spread preparations, the method of Fransz et al (1998) was used with some modifications. Immature flower buds were fixed in ethanol/acetic acid (3:1) for 2 h and stored at 4°C.…”

“…The technology is versatile and can be used on highly condensed metaphase complements, interphase nuclei, and even extended DNA fibers (Fransz et al 1996;de Jong et al 1999;Jackson et al 1998;Jiang and Gill 2006). A major breakthrough in plant cytogenetics has been the development of highresolution FISH on pachytene chromosomes (Fransz et al 1998(Fransz et al , 2000Peterson et al 1999;Cheng et al 2001). Pachytene chromosomes are favorite targets in FISH, especially in diploid plant species with low chromosome numbers and low-to medium-sized genomes.…”

Recognition and signal transduction in the expression of Phytophthora resistance in soybean [Glycine max (L) Merr]

“…In many plant species such as A. thaliana and M. tuncatula, chromosome arms are differentiated into euchromatic and heterochromatic regions (Fransz et al 1998;Fransz et al 2000;Kulikova et al 2001). Recently, Lin et al (2005) showed that in soybean heterocharomatic regions are also delimited from euchromatins.…”