Polyploidy-WesternWashingtonUniversity.ppt

Polyploidy …more than two haploid sets of chromosomes are present, 2n = diploid, 3n = triploid, 4n = tetraploid, etc. Autopolyploidy ...polyploidy resulting from the replication of one or more sets of chromosomes, …the additional set of chromosomes is identical to the normal haploid complement of that species. Autopolyploidy …can be induced by treating cells with the drug colchicine, colchicine: is a alkaloid derivative from the autumn crocus (Crocus veneris), ...inhibits microtubule polymerization, and thus inhibits the separation of chromosomes during meiosis. Colchicine Treatment cells undergo S-phase, no separation of chromosomes is accomplished, no cell division occurs, at telophase, the nuclear membrane reforms, treatment for one cell cycle leads to 4n cells. Amphidiploid …double diploid, 2n1 + 2n2 …have balanced gametes of the type n1 + n2, these gametes fuse to make fertile 2n1 + 2n2. Autopolyploidy Applications Treating a plant with colchicine often produces autopolyploidy, resulting in plants with larger flowers and/or fruit, Allopolyploidy Applications 4n x 2n = 3n? The creation of triploids can be accomplished by crossing a tetraploid with a diploid, Most triploid individuals are sterile. Generation of a Triploid Cells Meiosis in a Triploid Organism Who’d want to Eat That? Bananas, Seedless Watermelon, Most other seedless varieties, Some oysters. Environmental Applications? Polyploidy Summary More than 2 whole sets of chromosomes, Autopolyploidy, from the same genome, naturally occurring, or induced, often results in larger varieties, Allopolyploidy, from different genomes, naturally occurring, or induced, often results in larger varieties, Autotriploids, most often sterile can produce beneficial traits. Monoploidy …a haploid of a diploid is monoploid, …has one chromosome set. Monoploid male wasps, bees and ants have only 1 haploid genome, males develop from unfertilized eggs, gametes are formed by mitosis. Mo