Changes in triticale chromosome heterochromatin visualized by C-banding

Abstract

The distribution and characterization of heterochromatin in a series of cultivars, parents, new amphiploids and progeny of hexaploid triticale were comparatively studied using C-banding and morphometric analysis. A high level of intervarietal polymorphism was detected for the banding pattern. The chromosome pairs 4A and 1R presented the most constant pattern of heterochromatin distribution among 31 triticale lines studied. A total of 126 bands have been catalogued, from which 28, 59, and 39 belong, respectively, to the A, B and R genomes. The ratio of polymorphic bands per genome was 23/28, 36/59, and 30/39. The chromosomes displayed heterochromatin modifications consistent in both presence–absence and relative length of their content per genome, when passed from the parents to the amphiploids. Variations in the heterochromatin were also observed among sister plants coming from crosses between wheat and triticale. The heterochromatin content showed gradual tendencies either to increase or decrease in each genome during successive self-cross generations after that cross. The existence of a systematic process of variation of heterochromatin content in triticale is assumed, and the nature of this phenomenon is discussed.Key words: triticale, tetraploid wheat, rye, C-banding, heterochromatin.

Size matters in Triticeae polyploids: larger genomes have higher remodeling

“…Thus, the results collected in this review clearly point out, for the first time, the tendency in cereal-wide hybridization for parental genome size homogenization, which preferentially affects the larger genome to stabilize the newly formed polyploid species. Large scale rearrangement events are also observed resulting from the loss of telomeric heterochromatin, a mechanism used to obtain a more balanced nucleotype in triticale (Jouve et al 1989). Bernardo et al (1988) demonstrated a clear negative effect of rye heterochromatin on triticale meiotic pairing and that the loss of telomeric heterochromatic blocks are related to yield increase in hexaploid triticale (Gustafson and Bennett 1982).…”

Pollen‐Mediated Gene Flow in Triticale

“…We anticipate that triticale cultivars may also vary in PMGF. Triticale cultivars are heterogeneous, in part because of their variable genetic background and the amount of retention of the rye genome (Merker, 1971; Jouve et al, 1989; Kuleung et al, 2006). Quantification of PMGF between small plots has implications for the isolation distances used during cultivar development.…”

Estimation of the Highest Chromosome Number of Eukaryotes Based on the Minimum Interaction Theory

“…Direct tandem fission occurs by two steps: (1) dispersion of centromeres into arms by paracentric inversions and their inactivation, and (2) fissions at the inserted centromeres and their reactivation. Such a repeated dispersion of heterochromatin bands is known to have occurred in a grasshopper species, (Atractomorpha similis) (John & King, 1983), Parascaris equorum (Goday & Pimpinelli, 1986), and some plants such as triticales (Jouve et al, 1989) or Gibasis pulchella (Kenton et al, 1987).…”