Karyotypic changes in callus cultures from haploid and diploid plants of Crepis capillaris (L.) Wallr
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.
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TL;DR: Conditions are worked out for the isolation of streptomycin-resistant tobacco cell lines, from which diploid fertile plants carrying the streptomecin- resistant character, were regenerated and seedlings grown from seeds of self-fertilized resistant Str-r1 plants were resistant.
Abstract: THERE are few reports of the isolation of biochemical mutants from cultured plant cells1–3. We know of none describing plants which have been regenerated from these mutant cell lines and which still carry the mutant trait. We have worked out conditions for the isolation of streptomycin-resistant tobacco cell lines, from which diploid fertile plants carrying the streptomycin-resistant character, were regenerated. Seedlings grown from seeds of self-fertilized resistant Str-r1 plants were also resistant. The progeny obtained from crosses of Str-r1 plants and streptomycin sensitive (Str-s) plants showed non-Mendelian, uniparental transmission of the resistance trait.
450 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: The recovery of single gene mutations is evidence that plant tissue culture can be mutagenic in Lycopersicon esculentum.
Abstract: Plants were regenerated from cultured leaf explants of an inbred variety of Lycopersicon esculentum. Seeds were collected from the regenerated plants and sown in the greenhouse. The resultant plants were then evaluated in the field. Several monogenic mutations segregated in the progeny of regenerated plants. The recovery of single gene mutations is evidence that plant tissue culture can be mutagenic. Complementation tests revealed that one mutation was located on the long arm of chromosome 10.
244 citations
TL;DR: Regenerated plants with cytogenetic alterations were common, although Lodi cultures produced a higher frequency of cytogenetically abnormal plants at each regeneration cycle than Tippecanoe cultures.
Abstract: The frequency and types of chromosomal variability in regenerated Avena sativa L. plants were assessed by detailed meiotic analysis on 655 regenerated plants. Tissue cultures were initiated from immature embryos of the varieties Lodi and Tippecanoe and maintained by monthly subculturing. Plants were regenerated from 4-, 8-, 12-, 16- and 20- month-old cultures. Regenerated plants with cytogenetic alterations were common, although Lodi cultures produced a higher frequency of cytogenetically abnormal plants at each regeneration cycle than Tippecanoe cultures. After four months in culture, 49% of Lodi regenerated plants were cytogenetically abnormal, whereas only 12% of Tippecanoe regenerated plants were abnormal. The frequency of cytogenetically abnormal, regenerated plants increased with culture age. After 20 months in culture 88% of Lodi regenerated plants and 48% of Tippecanoe regenerated plants were cytogenetically abnormal. The most common cytogenetic alteration was chromosome breakage, followed by loss...
225 citations
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TL;DR: In vivo redox biosensing resolves the spatiotemporal dynamics of compartmental responses to local ROS generation and provide a basis for understanding how compartment-specific redox dynamics may operate in retrograde signaling and stress 67 acclimation in plants.
Abstract: In experiments with tobacco tissue cultured on White's modified medium (basal meditmi hi Tnhles 1 and 2) supplemenk'd with kiticthi and hidoleacctic acid, a slrikin^' fourlo (ive-told intTease iu yield was ohtaitu-d within a three to Tour week j^rowth period on addition of an aqtteotis exlrarl of tobacco leaves (Fi^'ures 1 and 2). Subse(iueutly it was found Ihiit this jnoniotiou oi' f^rowih was due mainly though nol entirely to inorj^auic rather than organic con.stitttenls in the extract. In the isolation of Rrowth factors from plant tissues and other sources inorj '̂anic salts are fre(|uently carried along with fhe organic fraclioits. When tissue cultures are used for bioassays, therefore, il is necessary lo lake into account increases in growth which may result from nutrient elements or other known constituents of the medium which may he present in the te.st materials. To minimize interference trom rontaminaitis of this type, an altempt has heen made to de\\eh)p a nieditmi with such adequate supplies of all re(iuired tnineral nutrients and cotntnott orgattic cottslitueitls that no apprecial»le change in growth rate or yield will result from the inlroduclion of additional amounts in the range ordinarily expected to be present in tnaterials to be assayed. As a point of referetice for this work some of the culture media in mc)st common current use will he cotisidered briefly. For ease of comparis4)n Iheir mineral compositions are listed in Tables 1 and 2. White's nutrient .solution, designed originally for excised root cultures, was based on Uspeuski and Uspetiskaia's medium for algae and Trelease and Trelease's micronutrieni solution. This medium also was employed successfully in the original cttltivation of callus from the tobacco Iiybrid Nicotiana gtauca x A', tanijadorffii, atitl as further modified by White in 194̂ ^ and by others it has been used for the
63,098 citations
01 Jan 1962
16,251 citations
TL;DR: The chapter discusses the changes in chromosomes of cells in vitro and of early stages of carcinogenesis, the basic concept of chromosomes and cancer is reviewed and the relationships between genetic background and carcinogenesis are discussed.
Abstract: Publisher Summary During a short period, a great deal of information has been accumulated on chromosomes of mammals, especially those of man. Both ascites tumors and tissue culture cells have been used extensively in various types of research. The chapter discusses the changes in chromosomes of cells in vitro and of early stages of carcinogenesis. In the chapter, the basic concept of chromosomes and cancer is reviewed and the relationships between genetic background and carcinogenesis are discussed. Problems concerning cell differentiation, carcinogenesis, and changes occurring in cells in vitro are parts of an entire problem that is the evolution of cell populations. Many trisomic individuals have been found in man, but they do not represent malignant growth. The only correlation between trisomics and cancer is the significantly high incidence of leukemia in mongolism. The diploid rat complement consists of 42 chromosomes of various lengths and centromeric positions. The chapter represents a typical cell taken from a primary culture of a rat embryo. Medium-sized chromosomes are all telocentric or subtelocentric. Metacentric chromosomes in the normal rat karyotype are all small elements.
146 citations
TL;DR: It has been concluded that Kinetin specifically triggers mitosis in mature pea root tissue cells which have undergone DNA- and chromosome-doubling by endomitotic reduplication before kinetin treatment.
Abstract: Pea root callus tissue cultivated for many months on a nutrient medium containing yeast extract and the auxin, 2,4-dichlorophenoxyacetic acid, is predominantly composed of dividing cells of the tetraploid chromosome number even though the initial tissues cultured from the root were known to consist in part of cells of the diploid chromosome number. In experiments designed to determine the basis for what appeared to be cell selection by the nutrient medium, 1-mm thick segments of 60 hr germinating seedling roots of the garden pea, Pisum sativum , excised 10–11 mm behind the root tip, were cultivated on a synthetic nutrient medium in which the yeast extract was replaced by a mixture of vitamins, amino acids, amides and urea. On such a medium, callus tissues developed, but only diploid cell mitoses were observed. Upon the addition of 1 ppm kinetin (6-furfurylaminopurine) to the synthetic medium, the number of cells in mitosis approximately doubled and a very high percentage of dividing cells possessed the tetraploid chromosome number. Lower concentrations of kinetin were proportionately less effective in stimulating mitosis and in bringing tetraploid cells into mitosis. From these studies it has been concluded that kinetin specifically triggers mitosis in mature pea root tissue cells which have undergone DNA- and chromosome-doubling by endomitotic reduplication before kinetin treatment. This conclusion is based on the following lines of evidence: ( a ) After 2 days of kinetin treatment, the tetraploid cells which enter mitosis showed diplochromosomes, indicating that chromosome doubling had been endomitotic; ( b ) Tetraploid mitoses were largely localized in mature cortical cells of the root while most diploid mitoses occurred in tissues of the central cylinder; ( c ) One-mm root tips cultured for up to 7 days in 1 ppm kinetin showed no tetraploid mitoses, which is expected since few or no endomitotically doubled cells are likely to occur in the apical meristem of the root. Certain experiments in which adenine sulfate or adenosine was fed the mature pea root segments together with kinetin suggest that an interaction between adenine and kinetin does occur in which adenine reverses in part the effect of kinetin on induction of mitoses in mature endomitotic cells.
144 citations
116 citations