Chromosome composition of an F2 Triticum aestivum×T. turgidum spp. durum cross analysed by DArT markers and MCFISH

Retention of D genome chromosomes in pentaploid wheat crosses

“…turgidum ssp. durum cross (2-49/Bellaroi) using Diversity Arrays Technology (DArT) markers and multicolour fluores-cence in situ hybridization (MCFISH) (Eberhard et al, 2010). This study observed that recombination of A and B genome loci from either parent was random in this F 2 generation.…”

“…Between 12 and 37% of the polymorphic markers in this array hybridized with the durum DNA, depending on the population (Table 1) D genome content Significant differences were observed in the D genome content of the different populations (Table 2). In all, 99 and 92% of the lines in the F 2 (Eberhard et al, 2010) and F 3 2-49/Bellaroi populations, respectively, inherited at least one D genome chromosome. Of these lines, 52% (F 2 ) A relatively low frequency of partial chromosomes was also observed in these populations ( Table 2).…”

“…These numbers stabilize in later generations at either 28 or 42 chromosomes, representing the chromosome numbers of the original parents, and reflect the inherent instability of unpaired chromosomes (Sax, 1922b;Thompson and Hollinghead, 1927;Kihara, 1982). Following this pioneering early research, geneticists have turned their attention elsewhere and only a few recent studies on pentaploid crosses have been published (Gilbert et al, 2000;Wang et al, 2005;Lanning et al, 2008;Eberhard et al, 2010), despite the emergence of new techniques that allow a much more detailed examination of the chromosomal complement and origin. Wang et al (2005) analysed the cytological and agronomic characteristics of 55 F 2 plants of a durum (female) by hexaploid (male) wheat cross.…”

“…We have also investigated four other hexaploid/durum crosses using DArT markers to determine whether the degree of D genome retention at F 2 and subsequent generations is dependent on either or both of the hexaploid and tetraploid parents. Finally, we have compared the relative incorporation of the A and B genomes of each parent in the progeny to determine whether the random segregation of parental materials, observed previously in one population (Eberhard et al, 2010), is typical of hexaploid/ durum crosses.…”

Genetic mapping in polyploids

“…physically observing the pairing behaviour of chromosomes during meiosis and (for example) counting the number of bivalents and multivalents that persisted into metaphase I (Westergaard, 1940;Cadman, 1943;Lamm, 1945;Swaminathan and Howard, 1953). FISH (Fluorescence in situ hybridisation) or GISH (Genomic in situ hybridisation) techniques could be used to identify homologous (and homoeologous) pairing during meiosis, although till now these techniques have mainly been used to establish base chromosomal number or identify sub-genomes in polyploids (D'Hont, 2005;Eberhard et al, 2010;Chester et al, 2012;Liu et al, 2016). Another approach to investigate meiosis is tetrad analysis (Preuss et al, 1994).…”