The cytology of triploid and tetraploidLycopersicum esculentum
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1. The multivalent configurations in the triploid and tetraploidLycopersicum esculentum are of the types which would be expected, if they were determined by a random distribution of chiasmata.
2. They vary in frequency from cell to cell, but remain statistically constant at successive stages, as they would be expected to do on this assumption.
3. The configurations (contrary to the opinion of previous authors, but as is expected on analogy with all other cases of chiasma pairing) are constant between diplotene and metaphase.
4. The metaphase chiasma frequency is highest in the diploid and lowest in the triploid. This is attributed to a similar difference in original chiasma frequency rather than to a greater reduction in number in the triploid during terminalisation.
5. The curve of variance is higher in the polyploids than in the diploids, as has previously been found inTulipa andHyacinthus.
6. The formation of trivalents and univalents in the triploid gives rise to irregularities in the second division, and to the formation of restitution nuclei.
7. The formation of quadrivalents in the tetraploid leads to numerical non-disjunction which is reflected in reduced fertility.
KeywordsChiasma Frequency Polar View Triploid Plant Chromatid Segregation Nather
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