scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Chromosomal variations in the callus tissues of Allium tuberosum and A. cepa

01 Mar 1980-Protoplasma (Springer-Verlag)-Vol. 102, Iss: 1, pp 171-176
TL;DR: The selective pressure of the culture media may have led to the manifestation of the genetic control of differential response to chromosome behaviour and growth in the two species of the same genus.
Abstract: Chromosome studies ofAllium tuberosum andA. cepa were made from one month to eighteen months old calluses. Different types of chromosomal variations like aneuploid number ranging from 28 to 31, tripolarity, lagging, micronuclei, haploid number etc. were noted inA. tuberosum, whereas inA. cepa the cells showed high chromosome numbers such as 32, 64 or more. The normal chromosome number (2n=16) occurred rarely. The selective pressure of the culture media may have led to the manifestation of the genetic control of differential response to chromosome behaviour and growth in the two species of the same genus.
Citations
More filters
Journal ArticleDOI
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

Journal ArticleDOI
TL;DR: Rapid propagation by the formation of shoots from calli of Aloe vera was obtained in the present investigation and callus formation was induced in stem segments from young axillary shoots grown on the underground rhizomatous stem.

72 citations

Journal ArticleDOI
TL;DR: It has been demonstrated that chromosomal changes were induced during the culture and that they did not pre-exist in the cultured barley embryos.
Abstract: Chromosome counts of ten morphogenic and seven non-morphogenic immature embryo derived calluses of barley,Hordeum vulgare L. cv. ‘Himalaya’, were determined. Morphogenic calluses carried the normal chromosome complement (2n=2x=14) in a majority of the cells. A low frequency of haploid (2n=x=7), triploid (2n=3x=21), tetraploid (2n=4x=28) and octoploid (2n=8x=56) cells were also observed. In contrast, non-regenerability of a callus was attributed to the cells having numerical and structural chromosomal changes. In these calluses, aneuploid cells around diploid, triploid, and tetraploid chromosome numbers predominated. It has been demonstrated that chromosomal changes were induced during the culture and that they did not pre-exist in the cultured barley embryos. Based on this study, it is suggested that chromosome analysis of a non-regenerable callus should be conducted before altering the media composition.

65 citations

Journal ArticleDOI
TL;DR: Callus induction and plant differentiation were obtained in an intergeneric hybrid of Saccharumofficinarum and Sclerostachya fusca and the study indicates the use of tissue culture technique for inducing intergeneric gene transfer inSaccharum hybrids.
Abstract: Callus induction and plant differentiation were obtained in an intergeneric hybrid of Saccharumofficinarum and Sclerostachya fusca. The sub clones showed morphological variation. Chromosome numerical variation was not observed but structural aberrations were noticed in some sub clones. The study indicates the use of tissue culture technique for inducing intergeneric gene transfer in Saccharum hybrids.

24 citations


Cites background from "Chromosomal variations in the callu..."

  • ...Variation among subclones due to gross changes in chromosome numbers such as aneuploidy or polyploidy have been reported in many plants, including sugarcane cultivars (Murashige and Nakano 1967; Kao et al. 1970; Bayliss 1973, 1980; Skirvin 1978; Roy 1980; Larkin and Scowcroft 1981; Heinz etal. 1969, 1977; Krishnamurthy and Tlaskal 1974; Liu and Chen 1976; Liu et al. 1977)....

    [...]

  • ...Variation among subclones due to gross changes in chromosome numbers such as aneuploidy or polyploidy have been reported in many plants, including sugarcane cultivars (Murashige and Nakano 1967; Kao et al. 1970; Bayliss 1973, 1980; Skirvin 1978; Roy 1980; Larkin and Scowcroft 1981; Heinz etal....

    [...]

Journal ArticleDOI
TL;DR: The chromosome analysis of regenerants derived from callus revealed variation in ploidy, such as 2n = 28, 29, 30, 31, 33 as well as normal tetraploid plants and other aneuploid variants.
Abstract: The effects of basal media and growth regulators on callus initiation and shoot regeneration have been investigated in wild Allium tuberosum (2n = 4x = 32). Callus initiation was greatest from flower bud explants cultured on MS medium supplemented with 2,4-D and BA at 1 mg l−1 each. Maximum number of shoots was obtained from callus grown on MS medium supplemented with NAA and BA at 0.2 and 2 mg l−1, respectively. The chromosome analysis of regenerants derived from callus revealed variation in ploidy, such as 2n = 28, 29, 30, 31, 33 as well as normal tetraploid. During the culture period for two generations, one aneuploid regenerant with 2n = 30 (named At30) showed better viability and growth than tetraploid plants and other aneuploid variants. In a karyotypic analysis of At30, the chromosomal positions of 5S and 18S-5.8S-26S rDNA were physically mapped by fluorescent in situ hybridization and compared to chromosomes of wild type A. tuberosum. Both wild type A. tuberosum and At30 exhibited two sets of 5S rDNA sites, one on the proximal position of the short arm of chromosome 3, and the other on the intercalary region on the long arm of chromosome 6. There was one 18S-5.8S-26S rDNA site in the secondary constriction including flanking short chromosomal segments of satellite and terminal regions on the short arm of chromosome 8 in wild type A. tuberosum. However, At30 showed only three labelled chromosome 8 indicating that this was one of the lost chromosomes of At30.

23 citations


Cites background from "Chromosomal variations in the callu..."

  • ...Reports concern plantlet regeneration from calli (Zee et al., 1977), somaclonal variation in callus tissue (Roy, 1980), andin vitro propagation by direct shoot proliferation (Pandey et al., 1992)....

    [...]

  • ...Two general types of ploidy variation, polyploidy and aneuploidy, are frequently found in tissue cultured cells (Roy, 1980)....

    [...]

References
More filters
Journal ArticleDOI
TL;DR: It was found that during the prolonged period of subculture there was a progressive loss of organ-forming Capacity in all tissue strains, paralleled by increasing abnormalities in the chromosomal constitution, including higher chromosome numbers and greater frequency of aneuploidy.
Abstract: A number of strains of callus tissues derived from 1-mm root tips of the garden pea, Pisum sativum L., cultivated on a complex medium containing yeast extract and 2, 4-D for eight years, were tested periodically for their capacity to initiate roots. Chromosomal cytological analyses accompanied each test. It was found that during the prolonged period of subculture there was a progressive loss of organ-forming Capacity in all tissue strains. At the outset all callus tissues could be stimulated to form normal diploid roots. After several years of continuous subculture, some callus tissues formed normal tetraploid roots. Still later, these callus tissues lost completely the capacity to initiate roots. This loss was paralleled by increasing abnormalities in the chromosomal constitution, including higher chromosome numbers and greater frequency of aneuploidy. Early in subculture normal diploid and tetraploid divisions were present in the callus tissues. Later, higher polyploids at 8n and 16n were more frequent, as well as aneuploids around these numbers. Some tissue strains after prolonged cultivation showed a wide range of chromosome numbers at the higher ploidy levels but completely lacked diploid divisions. It is suggested that the loss in organ-forming capacity is correlated with the increase in abnormality of chromosomal constitution. Differentiation of certain characteristic cell types was unaffected by these changes.

166 citations

Journal ArticleDOI
TL;DR: Two auxin-heterotrophic callus cultures of Crepis capillaris were studied and it has been found that new karyotypes also originate through chromosome rearrangements at the same ploidy level as the original explant.
Abstract: Two auxin-heterotrophic callus cultures of Crepis capillaris, one coming from an haploid plant and the other from a diploid one, were studied in regard to karyotypic changes for over a year. The degree of polyploidisation of the originally haploid culture was considerably higher than that of the diploid culture. The frequency of chromosome rearrangements was significantly higher in polyploidised karyotypes than in not polyploidised karyotypes and correspondingly greater in the “haploid” culture. However, the cytogenetical stability of the cultures cannot be measured only through their degree of polyploidisation: it has been found that new karyotypes also originate through chromosome rearrangements at the same ploidy level as the original explant.

165 citations

Journal ArticleDOI
TL;DR: Tobacco tissue cultures started from single cells disclosed that totipotentiality was not restricted to diploid cells but was possessed by and expressed with apparently equal ease by tetraploids cells, and the morphogenetically depressed situation was associated with a highly variable aneuploidy.
Abstract: A B S T R A C T Polysomatism in Nicotiana tabacum L. 'Wisconsin 38' was confirmed. Pith samples from the region of the stem 3.5-10.5 cm below the apex contained nearly equal proportions of diploid and tetraploid cells and samples obtained further down, 15.5-22.5 cm, showed predominantly tetraploid (circa 70%) and smaller proportions of diploid (9%), octaploid (16%), and aneuploid (5%) cells. Cultures of the callus from pith explants showed no evidence of diploid cells after 1 year, but did show roughly half 4n and 8n euploid and half -aneuploid cells. The callus after 6 years in vitro consisted entirely of aneuploid cells. The attainment of this predominance of aneuploid cells could account for the decline of callus growth and organ formation of tobacco tissue cultures. Tobacco tissue cultures started from single cells disclosed that totipotentiality was not restricted to diploid cells but was possessed by and expressed with apparently equal ease by tetraploid cells. The morphogenetically depressed situation was associated with a highly variable aneuploidy. With increase in somatic age the frequency of aneuploid cells increased and the level of ploidy among the aneuploid cells shifted from sub-tetraploidy to above tetraploidy.

137 citations

Book ChapterDOI
TL;DR: This chapter focuses on the plant tissue culture in relation to developmental cytology, and a promising approach is the microculture technique, with the necessary improvements, coupled with periodic photographic records or with microcinematographic studies of the same cell over a long period.
Abstract: Publisher Summary This chapter focuses on the plant tissue culture in relation to developmental cytology. The maintenance and growth of plant cells in vitro under aseptic conditions constitutes the plant tissue culture. Relatively little definitive work has been done in the general area of developmental plant cytology through the application of the tissue or cell culture techniques. Observations of polyploidy and other nuclear deviations in plant tissues are largely explicable as a disorganized manifestation of normal tendencies of somatic cells. The prevailing nuclear condition of a tissue culture can be seen to be responsive to differences in the medium and in the culture method. Thus, there are tools available for the experimental manipulation of these processes. In some cases, for example, Haplopappus, the problem may be one of finding conditions that minimize the aberrations, thereby supplying as clean a point of departure as possible for the full utilization of this excellent cytological tool. A promising approach is the microculture technique, with the necessary improvements, coupled with periodic photographic records or with microcinematographic studies of the same cell over a long period. Such studies, with various environmental factors carefully controlled, could be invaluable to a correlation of various events with the eventual fate of a cell.

106 citations