Intraspecific chromosomal and genetic polymorphism in Brassica napus L. detected by cytogenetic and molecular markers

Abstract

The application of DNA intercalator 9-aminoacridine allowed us to increase the resolution of chromosome C-banding and DAPI-banding patterns and to investigate chromosomal polymorphism in karyotypes of seven spring and six winter rape varieties. It was shown that the pericentromeric and intercalary C-bands of most of the chromosomes in spring rape were smaller in size and less polymorphic than those of winter rape. More 26S and 5S rDNA sites were found in the winter rape karyotypes than the spring varieties. Separate or colocalized 26S and 5S rDNA sites were revealed on chromosomes 4, 5, 6, 8, 10, 14, 15, 16 and 18. Intervarietal and intravarietal polymorphism of the number and chromosomal localization of rDNA sites were detected. The generalized idiogram of chromosomes of 13 Brassica napus varieties with account of all possibilities of C-banding patterns as well as localization of 26S and 5S rDNA sites were constructed. Polymorphism of the examined molecular and cytogenetic markers as well as the heterozygosis level of FAE1.1 gene controlling erucic acid synthesis in rapeseed was higher in the winter varieties than in the spring ones. The obtained data were in a atisfactory agreement with increased tolerance to environmental stress conditions of winter rape.

Phenotypic and molecular cytogenetic variability in calendula (Calendula officinalis L.) cultivars and mutant lines obtained via chemical mutagenesis

“…The seeds were germinated in Petri dishes on the moist filter paper at room temperature. Root tips (of 0.5–1 cm) were excised and stored for 16–20 h in ice-cold water with 1 µg/mL of 9-aminoacridine (9-AMA) (Sigma, St. Louis, USA) to inhibit chromosome condensation process and accumulate prometaphase chromosomes 51,61,62 . After the pre-treatment, the root tips were fixed in ethanol:acetic acid (3:1) fixative for 48 h at room temperature.…”

Gene conversion events and variable degree of homogenization of rDNA loci in cultivars ofBrassica napus

“…Brassica rapa , the presumed progenitor species of B. napus , has five loci (two major and three minor) per haploid set while the second presumed genome donor, B. oleracea , harbours two loci (Maluszynska and Heslop-Harrison, 1993). At the cytogenetic level, the cultivars of B. napus show genotypic differences in number, distribution and morphology of rDNA chromosomal loci (Snowdon et al , 1997; Fukui et al , 1998; Hasterok et al , 2001, 2006; Ali et al , 2005; Xiong and Pires, 2011; Amosova et al , 2014). Previous Southern blot hybridization revealed restriction fragments corresponding to both parents indicating Mendelian inheritance of rDNA in B. napus (Bennett and Smith, 1991; Waters and Schaal, 1996).…”

“…Third, the C-genome rDNA sites were not totally blocked by the B. oleracea -specific IGS probe (Howell et al , 2008). Finally, chromosome banding showed interpopulation variation in the amount and distribution of heterochromatin adjacent to or overlapping with NORs (Amosova et al , 2014). …”

Селекция Озимого Рапса Для Условий Лесной Зоны

“…Проведенное молекулярно-цитогенетическое исследование сортов рапса с применением GISH с зондами геномной ДНК сурепицы и капусты для разделения геномов и последующим FISH с зондами 45S и 5S рДНК, позволило изучить хромосомный полиморфизм А-и С-субгеномов по локализации кластеров рибосомных генов. У зимостойких сортов Норд и Северянин, с более широким районировананием, обнаружено сходство по распределению и размерам выявленных хромосомных маркеров и идентичность сочетаний полиморфных вариантов гомологичных хромосом, несущих локусы 45S и/или 5S рДНК [8][9].…”