Synthetic Allopolyploids

For the abstract see Plant Mol Biol. 2000 Jun;

In the June 2000 issue of Plant Molecular Biology (43(2-3):387-99)., Dr. Luca Comai at the University of Washington, Seattle, has published an interesting article, dealing with the molecular basis of the abnormal behavior of wild allopolyploids. When two copies of each parental genome are present in a species, it is called an allopolyploid. Natural allopolyploids are stable and adapted to the environment in which they grow. In contrast, synthetic allopolyploids are characterized by partial sterility leading to their instability and even death. They also show chromosomal rearrangements, an increase in the chromosome length and changes in the number and distribution of repeated DNA sequences. The latter phenomenon disrupts gene regulation and in some case causes gene silencing.. Incompatibility between parental genomes has been attributed to cause regulatory abnormalities. According to one model, transposons resident on the heterochromatin of a chromosome are activated resulting in irregular gene expression, perhaps by a silencing interaction between activated transposons and euchromatic genes. The author is of the opinion that this phenomenon of lesser intensity also occurs in intraspecific hybrids. According to the author, the study of allopolyploidy from this perspective, will help us understand and explain the factors such as those conditioning for hybrid vigor.

 

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