Genomic alterations in the interspecific hybrid Helianthus annuus×Helianthus tuberosus |
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Authors: | L Natali T Giordani E Polizzi C Pugliesi M Fambrini A Cavallini |
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Institution: | (1) Dipartimento di Biologia delle Piante Agrarie, Sezione di Genetica, Via Matteotti 1/B, I-56124 Pisa, Italy Tel.:+39 50 571567 Fax.+39 50 576750 E-mail: acavalli@agr.unipi.it, IT;(2) Scuola Superiore di Studi Universitari e Perfezionamento “S. Anna”, Via Carducci, I-56100, Pisa, Italy, IT |
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Abstract: | The genome of a Helianthus annuus (2n=34) ×Helianthus tuberosus (2n=102) hybrid was studied at cytological, biochemical and molecular levels and compared to those of the parental species.
Cytophotometric analyses showed that the hybrid has a 4C DNA content higher than expected and with a larger variability than
in the parents. This high variability is probably not related to chromosome-number variations since the hybrid always had
2n=68 chromosomes. Moreover, hybrid interphase nuclei showed lower heterochromatin condensation than the parental ones. Thermal
denaturation of genomic DNAs indicated that quantitative variation of some DNA families occurred in the hybrids compared to
parents. Finally, molecular analyses of DNAs restricted with different enzymes, after Southern blotting and hybridization
with HR probes, showed restriction patterns in the hybrid different from those observed in parents. These results indicate
that interspecific hybridization between H. annuus and H. tuberosus may determine quantitative variation of some DNA families and differential DNA methylations that probably modify the nuclear
structure. These phenomena are probable responses to a “genomic shock” following the interspecific cross.
Received: 22 May 1998 / Accepted: 4 June 1998 |
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Keywords: | Chromatin structure Genetic variability Genomic shock Helianthus Interspecific hybridization |
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