title: Centromere Orientation of Quadrivalents of Heterozygous Translocations and an Autoploid of GOSSYPIUM HIRSUTUM L.
abstract: Cytological observations of quadrivalents of heterozygous translocations in Gossypium hirsutum L. demonstrate that, in addition to alternate-1 and alternate-2 orientations, a third alternate orientation (alternate-3), which occurs as a three-dimensional, V-type configuration, can be identified.-Two additional types of disjunctions, the centromere orientations of which are rotational modifications of either adjacent or alternate configurations, were also observed in quadrivalents of a translocation heterozygote. These two types are rare, and both appear in the form of the Roman numeral X . The X and the alternate-3 types also occur in quadrivalents of an autoploid of G. hirsutum.-The two X types, along with adjacent-1, adjacent-2, alternate-1 and alternate-2 orientations, represent the six possible types of planar 2 x 2 random orientation of the four centromeres of a quadrivalent. Including the three-dimensional alternate-3 type, there are seven types of orientation.
authors.affiliation: Plant Sciences Department and Committee on Genetics, University of Arizona, Tucson, Arizona 85721.
authors.forename: J E
authors.initials: JE
authors.lastname: Endrizzi
authors.forename: D T
authors.initials: DT
authors.lastname: Ray
authors.forename: A C
authors.initials: AC
authors.lastname: Gathman