Origin of Chromosome Number Variation in Cultured Plant Cells
TL;DR: The range of chromosome number and structure observed in established cultures strongly points to the origin of these changes during culture, and the precise distribution of chromosomes at mitotic anaphase seems the most likely point at which instability could be induced in culture.
Abstract: CULTURED cells of both animal and plant tissues are characterised by instability of chromosome number and structure1,2. Although there is evidence3 that polyploid plant cell lines may arise from endoreduplicated nuclei in the original explant, the range of chromosome number and structure observed in established cultures strongly points to the origin of these changes during culture. Since the precise distribution of chromosomes at mitotic anaphase is the essential prerequisite for chromosome number stability5, this seems the most likely point at which instability could be induced in culture. It has been shown6,7 that, in culture, animal cells of various species are characterised by the presence of multipolar mitoses, a feature which would produce daughter nuclei with aneuploid chromosome numbers. Such multipolar mitoses have been briefly noted for plant tissue cultures8,9 but their frequencies have not been quantified.
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TL;DR: It is argued that this variation in plant cell culture itself generates genetic variability (somaclonal variation) that may be employed to enhance the exchange required in sexual hybrids for the introgression of desirable alien genes into a crop species.
Abstract: It is concluded from a review of the literature that plant cell culture itself generates genetic variability (somaclonal variation). Extensive examples are discussed of such variation in culture subclones and in regenerated plants (somaclones). A number of possible mechanisms for the origin of this phenomenon are considered. It is argued that this variation already is proving to be of significance for plant improvement. In particular the phenomenon may be employed to enhance the exchange required in sexual hybrids for the introgression of desirable alien genes into a crop species. It may also be used to generate variants of a commercial cultivar in high frequency without hybridizing to other genotypes.
3,113 citations
TL;DR: The cytogenetics of plant cell and tissue cultures and their regenerates will be discussed, and nuclear processes at and during callus induction will be followed.
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 (ami...
278 citations
TL;DR: Gene manipulation in plants improvement, Gene manipulation in plant improvement, and so on.
Abstract: Gene manipulation in plant improvement , Gene manipulation in plant improvement , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
273 citations
TL;DR: A novel approach to intra-clonal plant improvement which will utilize both the natural and induced variation associated with clonally propagated plants through various in vitro and in vivo procedures is suggested.
Abstract: This literature review suggests a novel approach to intra-clonal plant improvement which will utilize both the natural and induced variation associated with clonally propagated plants through various in vitro and in vivo procedures. Many plants obtained in this manner will be of single-cell origin and, hence, of pure mutant type avoiding the traditional chimerism phenomena of mutation breeding studies.
221 citations
TL;DR: Evidence was obtained for an inverse correlation between the growth phase and alkaloid content and cell organization (aggregation) on the other and the nature of the interrelationships between growth, differentiation and accumulation are considered.
Abstract: The relationship between alkaloid content, growth rate and differentiation was investigated in seven solanaceous species in culture. Evidence was obtained for an inverse correlation between the growth phase on the one hand and alkaloid content and cell organization (aggregation) on the other. Linear phase and stationary phase cells of Datura innoxia Mill, incorporated DL-(l-14C)ornithine-HCl differentially into protein and alkaloids with proportionately more label found in alkaloids in the stationary phase cells. On transferring callus of D. innoxia from high auxin medium (containing 10~5 M 2,4-D) to low auxin medium (containing 10-6 M, 2,4-D), the alkaloid content dropped concomitant with a decrease in chlorophyll content and an increase in growth rate and friability. The nature of the interrelationships between growth, differentiation and accumulation are considered.
193 citations
References
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Book•
01 Jan 1977
TL;DR: Plant tissue and cell culture is a process that involves cloning plants/plant cells from individual cells, organs or tissue in a nutrient medium under sterile conditions and forms an essential component of scientific research on plants.
Abstract: Powerful Plants is an Education and Outreach program brought to you by: Plant tissue and cell culture is a process that involves cloning plants/plant cells from individual cells, organs or tissue in a nutrient medium under sterile conditions. Scientists use this technique extensively to create exact genetic copies of a plant (clones) or generate large quantities of clone cells/organelles for further research. The use of tissue and cell culture has resulted in dramatic advances in plant science and forms an essential component of scientific research on plants. An example of use of plant tissue culture in the lab: Step 1) Scientist use transformation techniques to introduce a new gene of interest into tissue of a plant. Thus altering its genotype. Step 2) The transformed plant cells are then isolated and placed into sterile nutrient agar. Step 3) Each cell grows into a cluster of cells called a callus which are essentially unspecialised cells that haven’t decided what to be when they grow up! Step 4) Calluses are seperated and a plant hormone called cytokinin is added which stimulates growth of small leaf shoots. Step 5) Shoots are seperated and the addition of another plant hormone called auxin stimulates the growth of roots. Step 6) New plants are transferred to soil and grown to observe how the alteration of its genotype has affected its phenotype under extreme environmental conditions such as high salt, increased CO2, and drought.
707 citations
TL;DR: The cytological effects of 2,4-D and amitrole were studied for 12 species and the relative DNA values were found to be positively correlated with nuclear volumes.
Abstract: The cytological effects of 2,4-D and amitrole were studied for 12 species (Tradescantia clone 02, Allium cepa, Vicia faba, Triticum aestivum, T dicoccum, Hordeum vulgare, Secale cereale, Centaurea
88 citations
TL;DR: Cell suspension cultures of Triticum monococcum, Triticiam aestivum, Glycine max, Melilotus alba, and Haplopappus gracilis, were examined to determine whether chromosomal changes had occurred during culture.
Abstract: Cell suspension cultures of Triticum monococcum, Triticiam aestivum, Glycine max, Melilotus alba, and Haplopappus gracilis, were examined to determine whether chromosomal changes had occurred during culture. All cultures except H. gracilis showed change in chromosome number and the two species of Triticum showed abnormal karyotypes.
82 citations
80 citations