Cytogenetics of plant cell and tissue cultures and their regenerates
ABSTRACT After a short introduction, the cytogenetics of plant cell and tissue cultures and their regenerates will be discussed. In the first section discussion will focus on cytogenetic conditions “in vivo”, i.e., in the original explant: (I) widespread ocurrence of polysomaty as a consequence of endoreduplication; (2) aneusomaty, an important, though rare, cause of chromosome number variation in vivo; (3) occurrence of chromosome structural changes in differentiated tissues, especially in association with aging; (4) mixoploidy and/or gene mutations, either nuclear or organellar, present as mosaics or periclinal chimeras, especially in vegetatively propagated plants. In section two the discussion will follow with nuclear processes at and during callus induction: (1) mitosis induction in diploid (haploid) and endoreduplicated cells and initiation of cell lines with different ploidy levels; (2) chromosome endoreduplication prior to mitosis induction as a mechanism of polyploidization; (3) nuclear fragmentation (amitosis) followed by mitosis, a mechanism responsible for wide chromosome number variation in cultured cells. In the third section the discussion will consider cytogenetic conditions in medium‐ and long‐term culture: (1) stability at the diploid level with emphasis on the genetic makeup of the species; (2) polyploidy, both existing and originated during culture, and its competitive ability in chromosomally heterogeneous cultures; (3) haploidy: origin and fate; (4) aneuploidy: origin, selective advantage of particular karyotypes, etc.; (5) chromosomal and gene” mutations: preexisting vs. induced during culture. In section four the discussion will focus on cell fusion and somatic hybrid cell lines. The two main aspects of protoplast fusion: (1) for gene (cytoplasm) transfer or exchange; and (2) for the production of somatic hybrids by nuclear fusion, will be treated in detail. Section five will consider cytogenetic conditions in regenerated plants. How much of the genetic variation present in in vitro cultures may be incorporated into regenerated plants? In trying to answer this question, the discussion will concern: (I) cell selection during the regeneration process via adventitious shoots or somatic embryos; (2) polyploidy and aneuploidy in regenerates; (3) chromosome number rnosaicism (aneusomaty) a rather frequent occurrence in plants regenerated via adventitious shoots and intrasomatic cell selection; (4) haploidy, diploidy, and polyploidy in pollen‐derived plants; (5) other genetic variation in regenerates; (6) an analysis of the somatic hybrid plants produced so far. Finally, section six will cover ensuring genetic stability: micropropagation. After stressing the genetic continuity of the meristem cell line in higher plants, papers will be discussed which show maintenance of genetic stability in plants developed in vitro from shoot apex cultures, from axillary buds and latent meristems in some plant parts. The review will end with concluding remarks.
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ABSTRACT: Peppermint (Mentha piperita L.) belongs to a member of the mint family (Lamiaceae) and is widely used in food, cosmetics and medicines. This study was carried to investigate the variation of essential oil content and its composition during callus subculture of M. piperita. For callus induction from the leaf explant of peppermint, the basal medium was supplemented with various concentrations of 2, 4-D. The best callus induction rate (93%) of M. piperita. was obtained in MS medium containing 2 mg/l 2, 4-D. The induced peppermint callus maintained on Lin-Staba medium were studied during a period of 20th subcultures for the stability of essential oil production. Growth rates of peppermint callus increased during prolonged subculture. However, there was a progressive decrease of essential oil content and unstability of monoterpene productions when callus cultures were serially subcultured.CNU Journal of Agricultural Science. 01/2010; 37(3).
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ABSTRACT: To investigate early events of Agrobacterium-mediated transformation of apple cultivars, a synthetic green fluorescent protein gene (SGFP) was used as a highly sensitive, vital reporter gene. Leaf explants from four apple cultivars (`Delicious', `Golden Delicious', `Royal Gala' and `Greensleeves') were infected with Agrobacterium EHA101 harboring plasmid pDM96.0501. Fluorescence microscopy indicated that SGFP expression was first detected 48 h after infection and quantitative analysis revealed a high T-DNA transfer rate. Plant cells with stably incorporated T-DNA exhibited cell division and developed transgenic calli, followed by formation of transgenic shoots at low frequencies. The detection of SGFP expression with an epifluorescence stereomicroscope confirmed the effectiveness of SGFP as a reporter gene for detection of very early transformation events and for screening of putative transformants. The efficiency of the transformation and regeneration process decreased ca. 10000-fold from Agrobacterium infection to transgenic shoot regeneration, suggesting that factors other than Agrobacterium interaction and T-DNA transfer are rate-limiting steps in Agrobacterium-mediated transformation of apple.Plant Molecular Biology 01/1998; 37(3). · 3.52 Impact Factor
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ABSTRACT: The karyotype of the dihaploid SVP1 line of S. tuberosum (2n=2x=24) showed two nucleolar chromosomes with differently sized satellites. The diploid SVP5 line (2n=2x=24) and tetraploid regenerants of S. phureja had larger but similar satellites. Somatic hybrids between the diploid lines of these potato species with genome combinations 4 tub + 2 ph (plants 1-3), 2 tub + 4 ph (plants 4-7) and 4 tub + 4 ph (plant 8) had lost 2 phureja nucleolar chromosomes if 4 phureja genomes were present. One phureja nucleolar chromosome of plants 1-3 and both of plants 5 and 7 had rearranged satellites. Elimination of the two nucleolar chromosomes occurred preferentially, was under genetic control, and probably took place during early callus development. NOR activity resulting in rear-rangements between NORs may have caused the elimination.Theoretical and Applied Genetics 04/1987; 73(6):878-82. · 3.66 Impact Factor