An Analytical Study of Chromosome Behavior in a Wheat Haploid

Abstract

Bivalents, univalents, end-to-end and side-by-side associations, also chromosome distributions to the poles were associatively recorded for each of approximately 2000 meta-anaphase cells of a haploid Triticum aestivum L. It was demonstrated that the distribution of the univalents to the polar groups was not random. An inverse relationship between side-by-side association and bivalent frequencies was also demonstrated, and this formed the first in a series of analytical steps which led to a description of chromosome movement in the haploid. The validity of certain assumptions concerning chromosome behavior was tested using the χ2 method; for others, confirmatory observations were made in monosomic cells.

Aneuploids and the cytogenetic structure of wheat varietal populations

“…However, chromosomes which have paired at prophase without chiasmaformation sometimes remain secondarily associated as univalents (Person, 1955 Riley and Chapman, 1957). Occasionally the secondarily associated univalents then orientate on the first metaphase plate and separate one to each pole in late anaphase.…”

Male Meiosis, Microsporogenesis and Pollen Grain Study in Inula cuspidata C. B. Clarke (Asteraceae)

“…The 2 meiotic stages, metaphase I and anaphase I, in such cases are indistinguishable as the univalent chromosomes remain scattered in the meiocytes. In such cases, the term meta-anaphase is used as coined by Person (1955). The spontaneous occurrence of such plants showing high frequency of univalent chromosomes and associated meiotic irregularities during male meiosis is already known in other plant species (Kaul andMurthy 1985, Singh 2002).…”

The additional heterochromatic chromosome and its influence on sex chromosome pairing in Rumex

“…According to Levan (1942) nonhomologous pairing in haploid rye seems to start at the heterochromatic segments. Person (1955) reported e-e (end-to-end) and s-s (side_by-side) association of chromosome during meiosis in haploid Triticum aestivum. He suggested that homology is not a factor in the formation of e-e associations.…”

“…PAIRING between partner chromosomes is specific and depends on homology, while nonspecific pairing between nonhomologous regions is, in most cases, the result of heterochromatic fusion (Riley and Law, 1965;Riley and Chapman, 1957;Person, 1955). The introduction of a new, experimentallyinduced, heterochromatic chromosome into normal male plants of R. thyrsifiorus changes the pattern of sex chromosome pairing and cause conjugation between nonhomologous partners.…”