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  • 1
    ISSN: 1432-0983
    Keywords: Nuclear-cytoplasmic interactions ; Mitochondrial genome ; Chondriome variability ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Although the mitochondrial genomes of the Chinese Spring and Aquila varieties of wheat are normaly similar in organization, this is not so in tissue cultures initiated from their immature embryos where the mitochondrial genomes of both are rearranged and in different, characteristic, ways. However, the mitochondrial genomes of tissue cultures of reciprocal F1 crosses between these varieties were almost identical to one another, showing that nuclear genes control the rearrangement processes. These rearrangements are either due to the appearance of new structures or else result from changes in the relative amounts of subgenomic components. The severe reduction in the amount of certain molecular configurations in tissue cultures from reciprocal crosses is probably due to the presence of dominant information in the Aquila nuclear genome. Data obtained from tissue cultures initiated from F2 embryos of the cross Aquila x Chinese Spring suggest that at least two complementary genes are involved in this control. In contrast, the presence of new molecular arrangements appears to be under the control of a dominant allelic form of a Chinese Spring gene or genes. Thus, this study demonstrates that at least two sets of nuclear genes control the reorganization of the mitochondrial genome which occurs when tissue cultures are initiated from the immature embryos of wheat.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2242
    Keywords: Wheat ; Somatic tissue culture ; Mitochondrial DNA ; Chondriome variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have previously shown that the mitochondrial genome of long-term tissue cultures prepared from immature embryos of several varieties of cultivated wheat underwent variety-specific rearrangements resulting from either changes in the relative amounts of subgenomic components or from the appearance of novel genomic configurations. In the present work, both categories of rearrangements were studied in long-term tissue cultures initiated from other explants (shoot meristem, young leaf base, young root tip, immature inflorescence) of the same wheat variety (Chinese Spring) and were compared to those previously obtained with immature embryo cultures. Two main patterns of reorganization were found in a region of the mitochondrial genome known to be hypervariable in structure. In addition, some of the novel subgenomic configurations were obviously organ/tissue-specific whereas others were present in more than one type of organ. In several instances, the age of culture was found to determine the degree of mitochondrial DNA rearrangement. The data presented in this study strengthen the hypothesis of an association between a particular organization of the mitochondrial genome in tissue culture and its regeneration capacity.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2242
    Keywords: Wheat ; Somatic tissue culture ; Regenerated plants ; Mitochondrial DNA ; Chondriome variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have previously shown that tissue cultures derived from various explants of the wheat variety Chinese Spring exhibit organ/tissue-specific changes in the organization of their mitochondrial genome. The aim of this work was to study the influence of passage out of in-vitro culture, and subsequent plant regeneration, on the in vitro “induced” reorganization of this genome. In all cases but one, subgenomic configurations present in both the donor parent and the tissue culture were evident, in corresponding regenerated plants. The presence, in regenerated plants, of subgenomic configurations found in tissue culture but undetectable in the donor parent appeared to be both timeand organ/tissue-dependent. Moreover, when present, these novel organizations were not systematically found in all regenerated plants. Finally, novel subgenomic configurations were specifically detected after passage out of in-vitro culture. As these results were obtained from a single plant variety, they clearly confirm the extreme plasticity of mitochondrial genome structure in response to in-vitro culture.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2242
    Keywords: Mitochondrial DNA ; Chondriome variability ; In vitro culture ; Plant regeneration ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plants have been regenerated from short-and long-term in vitro somatic tissue cultures made from immature embryos of the hexaploid wheat cultivar “Chinese Spring”. The mitochondrial genome organization of each regenerated plantlet was studied, after one selfing, by probing Sal I-restricted total DNA with cloned Sal I fragments of wheat mitochondrial DNA derived from a segment of the genome, which displays marked structural changes in response to in vitro culture. Short-term in vitro cultures give rise to regenerated plants whose mitochondrial genome organization is either close to that of the parental cultivar or to that of embryogenic callus cultures, except for a single plant which has an organization resembling that of short-term non-embryogenic cultures. In contrast, all but one of the plants regenerated from long-term cultures exhibited a mitochondrial genome organization similar to that of long-term nonembryogenic cultures. In addition, extra labelled bands were detected in some of the regenerated plants with two of the probes used. These results emphasize the importance of the duration of the in vitro step preceding the regeneration process: the longer it is, the higher the probability is of obtaining mitochondrial DNA variability in regenerated plants. Furthermore, since increasing the duration of the in vitro stetp results in the production of regenerated plants with a mitochondrial genome organization resembling that of non-embryogenic tissue cultures, the question is thus raised as to whether regeneration from long-term cultures is suitable for use in plant breeding.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2242
    Keywords: Triticum ; Allopolyploidy ; Mitochondrial DNA ; Somatic tissue culture ; Chondriome variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Southern-blot hybridizations of total DNA to mitochondrial DNA (mtDNA) probes were used to investigate the extent of mtDNA variability in cultures derived from immature embryos of diploid (Triticum monococcum, genomic formula: AA, T. tauschii, genomic formula: DD), allotetraploid (T. durum cv “Creso”, genomic formula: AABB), and allohexaploid (T. aestivum, genomic formula: AABBDD) wheat species. Similar distinct changes in mtDNA organization were observed in in vitro cultures of the derived tetraploid and the hexaploid species with related genomes. The tetraploid and hexaploid species share the B genome and mtDNA variability in in vitro culture is known to be under nuclear control. These results suggest that a study of B genome diploids and other polyploid combinations would now shed light on whether or not mtDNA variability in tissue cultures is under B-genome control.
    Type of Medium: Electronic Resource
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