Allium Ampeloprasum— A Polyploid Complex II. Meiosis and Relationships between the Ploidy Types

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Abstract
The study of meiosis in A. ampeloprasum in Israel showed that in subsp. ampeloprasum the chiasmata are localised proximally to the centromere, whereas they are terminal or subterminal in subsp. truncatum. It was found that localisation of chiasmata reduces multivalent formation in 4x, 5x and 6x plants of subsp. ampeloprasum. The distribution of ploidy levels of subsp. ampeloprasum (4x, 5x and 6x) and of subsp. truncatum (2x, 3x, 4x) in Israel is presented on maps. In both subspecies the tetraploid level is the most frequent. Hexaploids are rather common and probably arise from time to time from 4x in various localities. Pentaploids are fairly rare and possibly arise by hybridization between tetra- and hexaploids. Diploids are rare. They may have been replaced to a great extent by the apparently more vigorous and successful tetra- and triploids. Triploids seem to be maintained mainly by means of efficient vegetative reproduction; however, pollination of triploids by diploid pollen of tetraploids may occur, resulting in production of tetraploid and triploid offspring.