Abstract
Shoot organogenesis was induced from 2- and 6-week-old callus derived from the leaves of Arabidopsis thaliana ecotype Columbia (2n = 10). Regenerated plants were evaluated for chromosomal variations by means of flow cytometry and fluorescent in situ hybridization (FISH). Flow cytometric measurements revealed the occurrence of diploid, tetraploid, and octoploid plants among the regenerants of 2-week-old calli, whereas only diploid and tetraploid plants were regenerated from the 6-week-old calli. Chromosome counting showed that plants developed from the 2-week-old calli exhibited mixoploidy and a high frequency of aneuploid cells. These plants were infertile and displayed altered morphology. FISH with 5S and 25S rDNA probes allowed to detect some structural chromosomal rearrangements in regenerated plants. Along with cells which exhibited correct localisation of rDNA loci, also cells bearing chromosomal translocations, deletions or duplications were found. The type of structural aberrations varied between diploid and tetraploid regenerants.
Highlights
Plant tissue culture is one of most important tools necessary for successful conducting plant research and broadly used in commercial biotechnology
Regenerated plants were evaluated for chromosomal variations by means of flow cytometry and fluorescent in situ hybridization (FISH)
The system of indirect organogenesis of A. thaliana, which is based on callus, shoot and root induction with the use of specific media allows for a high efficiency of regeneration; it depends on the ecotype, the type of explant, the culture conditions and the medium and hormones employed (Negrutiu 1976; Akama et al 1992; Candela et al 2001)
Summary
Plant tissue culture is one of most important tools necessary for successful conducting plant research and broadly used in commercial biotechnology. A variation originating in cell and tissue culture is referred to as somaclonal variation (Larkin and Scowcroft 1981). The phenomenon of variation in the in vitro culture is one of the most frequently studied phenomena, but the causes of the somaclonal variation remain unclear and cannot be manipulated. Variation in the number of chromosomes (aneuploidy and polyploidy) and/or their structure is one of the crucial problems in plant cell culture and was reviewed as one of the most significant reasons for the somaclonal variation (Karp 1995; Peschke and Phillips 1992). Karyological changes in cells and tissues cultured in vitro occur both in mitotically dividing cells and in interphase nuclei. The most important alterations include chromosomal aberrations, changes in the content of nuclear DNA, somatic crossing-over and cell cycle disorders.
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