Plant Genome II Conference
Town & Country Conference Center, San Diego, CA, January, 1994.
PG-II: DEVELOPMENT AND USE OF CHROMOSOMALLY UNBALANCED CYTOGENETIC
STOCKS FOR PHYSICAL CHROMOSOME MAPPING IN COTTON (GOSSYPIUM
HIRSUTUM L.)
DEVELOPMENT AND USE OF CHROMOSOMALLY UNBALANCED CYTOGENETIC
STOCKS FOR PHYSICAL CHROMOSOME MAPPING IN COTTON (GOSSYPIUM
HIRSUTUM L.)
Charles F. Crane, Robert Hanson, Wayne A. Raska, Don G. Czeschin,
H. James Price, and David M. Stelly, Department of Soil and Crop
Sciences, Texas A&M University, College Station, TX 77843.
Numerous chromosomal translocations, a number of monosomics,
and a few telocentrics, have been recovered over the past 50
years in cotton after irradiation or interspecific hybridization.
These rearranged or deleted chromosomes can be combined in
informative ways for physical mapping of DNA probes relative to
centromeres and translocation breakpoints by meiotic in situ
DNA hybridization (ISH). The informative stocks have one of the
following meiotic metaphase I configurations: (1) a heteromorphic
telocentric bivalent), (2) a telocentric chain quadrivalent, or
(3) a duplicate-deficient chain quadrivalent. The second of
these types, which arises from a telocentric x translocation
homozygote cross and therefore is designated TeTT, is
particularly useful because each chromosomal region occupies an
unambiguous position in the quadrivalent. Meiotic ISH with 18S
and 5S ribosomal DNA probes to TeTT quadrivalents involving
chromosomes 5, 9, and 23, has confirmed the localization of 18S
and 5S sites to opposite arms of chromosome 9, and to the same
arm of chromosome 23. The distribution of these ISH sites also
demonstrated that the breakpoints for the TT5-9 translocation lie
in the long arms of each chromosome, opposite the positions
reported by Menzel based on the meiotic analysis of hybrids to
other translocation homozygotes.
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