Structural alterations in chromosomes of hexaploid triticale and their effects on cytological and yielding characters 2. experimental data concerning the cytological behavior of some heterochromatin deficient triticale lines

Huelgenhof, E.; Schlegel, R.

Biologisches Zentralblatt 104(3): 245-259


ISSN/ISBN: 0006-3304
Accession: 006488899

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Hexaploid winter triticale lines with a gradually reduced amount of telomeric heterochromatin on certain rye chromosomes were used to analyze the relationships between heterochromatin content and meiotic pairing behavior at metaphase I. The chromosomes were differentially stained by means of the Giemsa C-banding procedure. The modifications were characterized either by lack or reduction of telomeric blocks in the short arms of the chromosomes 4R and 5R as well as in the short and long arms of chromosome IR and the long arm of chromosome 3R. Most of the pairing failure was caused by the heavy Giemsa-stained rye chromosomes. The removal of telomeres decreased the univalent frequency. The karyotype containing deficiencies on both of the homologous arms of 1RS, 1RL, 4RS and 5RS exhibited about 30% less univalents than the original karyotype, and these effects were additive. Quite a different behavior was true for the rod bivalents. The association of the homologs showing the prominent terminal band on the short arm only was mostly restricted to the long arm, and exceeded the expected frequency. Even chromosomes marked by heterozygous deletions predominantly formed rods. The loss of heterochromatic telomeres in one of the 2 homologous chromosome arms reduces the chiasma frequency. The absence of large blocks of heterochromatin apparently has no effect on the transmission of affected gametes. The investigation of the offsprings of isolated plants which were heterozygous for several heterochromatin deficiencies demonstrated no deviations from monohybrid or dihybrid segregation, depending upon whether 1 or 2 chromosome pairs were modified.