Origin of nuclear aberrations and seed shrivelling in triticale: a re-evaluation of the role of C-heterochromatin

Abstract

The effect of C-heterochromatin on the origin of nuclear aberrations and seed shrivelling was investigated in four triticale lines, each consisting of a pair of genotypes designated A (producing plump, well-filled seeds) and B (with shrivelled seeds). The relative DNA content in the polyploid nuclei of endosperms, 42 h after pollination, was estimated by Feulgen cytophotometry. The observed frequency of polyploid nuclei, 0.85% and 5.69%, respectively, in the two genotypes 1A and 1B caused a reduction in nuclear number of 3.27% and 18.54% at this stage of development. In the B genotype, producing shrivelled grains, polyploidisation started earlier than in the A genotype. An examination of the Giemsa karyotype of the mitotic chromosomes of the rye genome in the four triticale pairs revealed no considerable differences in the banding pattern between the A and B genotypes. Giemsa staining of endosperms, 2-3 days after pollination, clearly showed that bridges without bands, most probably involving wheat chromosomes, were also present. An experiment designed to simulate spindle disturbances in developing endosperms by colchicine treatment revealed that polyploid nuclei can be formed by spindle malfunctions as well.

Meiotic expression of modified chromosome constitution and structure in × Triticosecale Wittmack

“…Accordingly, a series of studies have been carried out to analyse the chromosome constitution and the amount of telomeric heterochromatin of rye chromosomes in secondary triticale lines (Lukaszewski and Apolinarska, 1981;Ziauddin and Kasha, 1982;Varghese and Lelley, 1983; Gustafson et a!., 1985;Lukaszewski, 1986).…”

Scanning electron microscopy of mature grains of rye, wheat and triticale with emphasis on grain shrivelling

“…Aberrant cell divisions, involving chromatin bridge formation and the appearance of polyploid restitution nuclei in the endosperm, at early stages of development, have been connected with grain shrivelling (BEN-NETT 1977;KALTSIKES et al 1975;VARGHESE et al 1984;KALTSIKES and GUSTAFSON 1985). The chromatin bridges were between rye chromosomes, which have heterochromatic regions at their ends and between wheat chromosomes which lack such telomeric heterochromatin (VARGHESE and LELLEY 1983). A review of the literature on the possible role of rye heterochromatin in relation to grain shrivelling in triticale and a cytological analysis of the triticale lines studied here can be found in an accompanying paper (HENEEN and BRISMAR 1987).…”

Phenotypic, cytogenetic and spike fertility characterization of a population of male-sterile triticale

“…Several irregularities in the meiotic process and in pollen grain viability have been described in triticale (Shkutina and Khvostova, 1971;Falcão et al, 1981;Jung et al, 1985;Hohmann, 1993). There are several hypotheses regarding the cause of meiotic irregularities in this crop, including structural dissimilarity between wheat and rye chromosomes (Varghese and Lelley, 1983;Jung et al, 1985;Lelley, 1992), insufficient time for chiasmata formation in rye chromosomes during synapse (Oettler, 2005), premature disjunction of bivalents (Lelley, 1974), difficulties in cytoplasmic interactions or in generating univalent chromosomes (Sisodia and McGinnis, 1970) and problems during chromosome paring (Lelley, 1992).…”