Characterization of the A and C Genomes of Brassica Campestrisand B. Alboglabra

Abstract

Meiosis was studied in pollen mother cells of two Brassica cumpestris (AA) and one B. alboglabru (CC) accessions, their resynthesized B. napus amphidiploids (AACC), and digenomic hybrids produced (AAC). The two parental species exhibited different chromatin condensation patterns at diakinesis, which enabled the differentiation between genomes and the detection of auto-and allosyndesis in the amphidiploids and digenomic hybrids. Corresponding chromatin condensation differences were manifested at mitotic prometaphase. The diploid accessions were characterized as to glucosinolate composition, restriction fragment length polymorphism (RFLP), random amplified polymorphic DNA (RAPD), and isozyme patterns. All 20 RFLP probes and 9 RAPD primers tested gave discriminatory bands for the A and C genomes. For isozymes, 14 out of 17 analysed loci had alleles that discriminated between these genomes. In addition to the already established locations of flower colour, erucic acid content, and leucine aminopeptidase enzyme genes in the C genome, other genome-specific isozyme and DNA-based markers amounted to 89 and 112 in the two B. campestris accessions and 135 in the B. alboglabra accession. Sinigrin synthesis is an additional character controlled by the C genome, The combination of different marker systems and cytological techniques for the characterization of the A and C genomes and their constituent chromosomes has obvious implications for plant breeding, assessment of gene introgression in nature, and evolutionary studies. W.K. Heneen, Department of Plant Breeding Research, The Swedish University of Agricultural Sciences, S-268 31 Svalov, SwedenThe genus Brassica comprises a large number of crops that serve as sources of oilseed, and as vegetables and fodder. In economic terms, the diploid species B. campestris L. (2n = 20, genome AA) and B. oleracea L. (2n = 18, CC) and their amphidiploid B. napus L. (2n = 38, AACC) are globally the most important. An understanding of the organization of the A and C genomes at the chromosomal and molecular levels in the diploids and the amphidiploid is fundamental for phylogenetic studies, manipulation in plant breeding, and the assessment of interspecific gene introgression in nature.Characterization of the A and C genomes and their relations to other genomes in Brassica and related genera has been the subject of many detailed studies that were primarily based on cytological, biochemical, or molecular analysis. Beginning with the classical work of U (1935), hybridization and cytogenetical analysis have elucidated the close relatedness of the A and C genomes, their intraand intergenome chromosome homoeologies, and their apparent secondary polyploid origin ( H A R - BERD and MCARTHUR 1980;INOMATA 1980;PRAKASH and HINATA 1980; ARMSTRONG and CIECHOWSKI 1985; ATTIA and R~BBELEN 1986a,b; ATTIA et al. 1987;TAI and IKONEN 1988;CHOPRA and PRAKASH 1991;CHENG et al. 1994b). Recently it has been possible to characterize the different chromosomes in the A and C genomes through the use of banding t...

Meiotic nondisjunction in resynthesized Brassica napus and generation of aneuploids through microspore culture and their characterization

“…The occurrence of high number of univalents and multivalents, including rarely documented penta-, hexa-, and heptavalents in resynthesized B. napus reported here was in agreement with previous observations by Heneen et al (1995), indicating high degree of homoeologous pairing as a result of intragenomic duplications or the archaic homoeology of A/C genomes (Prakash and Hinata 1980). Chromosome rearrangements arising from homoeologous recombination were suggested to be the main reason for the genetic changes observed in the newly synthesized allopolyploids (Song et al 1995;Gaeta et al 2007).…”

“…Inomata (1980) observed 0-1 trivalent and 0-1 quadrivalent while Sarashima (1973), Prakash and Raut (1983) found a maximum of two trivalents and three quadrivalents. Heneen et al (1995) documented much higher numbers of univalents ranging up to 9, as well as the rare occurrence of penta-, hexa-, and heptavalents. Chromosome bridges, fragments and lagging were also reported by Song et al (1993) and Heneen et al (1995).…”

“…Heneen et al (1995) documented much higher numbers of univalents ranging up to 9, as well as the rare occurrence of penta-, hexa-, and heptavalents. Chromosome bridges, fragments and lagging were also reported by Song et al (1993) and Heneen et al (1995). Pollen fertility ranged from 45 to 97%.…”

Cytological and morphological analysis of hybrids between Brassicoraphanus, and Brassica napus for introgression of clubroot resistant trait into Brassica napus L

“…napus through homeologous recombination between A, C and R genomes is eminently possible. Several cytological studies have shown high frequency of homologous chromosome pairing among C subgenomes of Brassica species [14, 30, 38]. Our results showed that the C subgenomes in Brassicoraphanus (RRCC, 2n = 36) and B .…”

Disruption of a CAROTENOID CLEAVAGE DIOXYGENASE 4 gene converts flower colour from white to yellow in Brassica species

“…in U's triangle (Nagaharu, 1935) is yellow, although some white-flowered varieties exist in subspecies of the B. oleracea cytodeme. White flower has been reported in rapeseed lines resynthesized through interspecific hybridization between B. rapa and white-flowered B. oleracea (Chen et al, 1988;Heneen et al, 1995;Zhang et al, 2002). Genetic analysis of flower colour in Brassica has been conducted since 1929 (Pearson, 1929), and has been shown to be controlled by a single nuclear gene in Brassica species containing the C genome or subgenomes, with white colour dominant over yellow (Pearson, 1929;Zhang et al, 2002;Liu et al, 2004;Huang et al, 2014).…”