Chromosome Rearrangements Caused by Double Monosomy in Wheat-Barley Group-7 Substitution Lines

Abstract

Interspecific or introgressive hybridization is one of the driving forces in plant speciation, producing allopolyploids or diploids with rearranged genomes. The process of karyotype reshaping following homoploid interspecific hybridization has not been studied experimentally. Interspecific hybridization is widely used in plant breeding to increase genetic diversity and introgress new traits. Numerous introgression stocks were developed for hexaploid wheat Triticum aestivum L. (2n = 6x = 42, genome AABBDD). Double monosomic lines, containing one alien chromosome from the tertiary gene pool of wheat and one homoeologous wheat chromosome, represent a simplified model for studying chromosome rearrangements caused by interspecific hybridization. The pairing of a chromosome from the tertiary gene pool with a wheat homoeologue is restricted by the activity of the wheat Ph1 gene, thus, rearrangements caused by chromosome breakage followed by the fusion of the broken arms can be expected. We analyzed chromosome aberrations in 4 sets of lines that originated from double monosomics of barley (Hordeum vulgare L.) chromosome 7H and wheat group-7 chromosomes with dicentric or ring chromosomes. The dynamics of wheat-barley dicentric chromosomes during plant development was followed and an increased diversity of rearrangements was observed. Besides the targeted group-7 chromosomes, other wheat chromosomes were involved in rearrangements, as chromosomes broken in the centromeric region fused with other broken chromosomes. In some cells, multi-centric chromosomes were observed. The structure and dosage of the introgressed barley chromatin was changed. The transmission of the rearrangements to the progenies was analyzed. The observed aberrations emphasize the importance of cytogenetic screening in gene introgression projects.

Molecular cytogenetic characterization of a novel wheat–Psathyrostachys huashanica Keng T3DS-5NsL•5NsS and T5DL-3DS•3DL dual translocation line with powdery mildew resistance

“…These results indicate that the short arm and partial long arm of wheat chromosome 5D close to the centromere were replaced by P. huashanica chromosome 5Ns. Many studies found that homoeologous chromosomes are remarkably conserved and any missing genetic content is usually complemented by corresponding homoeologous chromosomes [34][35][36][37]. In the H8911 × Trs-372 cross, because Trs-372 only carries A and B genomes, chromosome recombination mainly occurred between the D and Ns genomes, in particular, the reciprocal translocation between wheat 5D and P. huashanica 5Ns chromosomes that generated a new 5DL-5NsL·5NsS chromosome.…”

Pairing and Exchanging between Daypyrum villosum Chromosomes 6V#2 and 6V#4 in the Hybrids of Two Different Wheat Alien Substitution Lines

“…At present, substitution lines are mainly derived from five methods including spontaneous substitution, monosomic substitution, telosomic substitution, nullisomic backcrossing, and tissue culture [27,28,29,30]. In theory, the homoeologous chromosomes of three wheat subgenomes can be replaced with alien chromosomes, forming three different types of alien substitution lines.…”

Cytological and genetic effects of rye chromosomes 1RS and 3R on the wheat-breeding founder parent Chuanmai 42 from southwestern China

“…However, the 5BS.7BS and 5BL.7BL translocations had no signi cant effects on PH, tillers, spikelets, and TGW (Yang et al 2021). A previous study indicated that wheat chromosomes are involved in rearrangements, such as chromosomal breakage and fusion, during the introduction of barley chromosome 7H into wheat to generate a double monosomic accession (Danilova et al 2018). The presence of alien chromosomes easily leads to additional chromosome structural changes, which may further diversify the host chromosomes.…”