The Use of Pentaploid Crosses for the Introgression of Amblyopyrum muticum and D-Genome Chromosome Segments Into Durum Wheat

Abstract

The wild relatives of wheat provide an important source of genetic variation for wheat improvement. Much of the work in the past aimed at transferring genetic variation from wild relatives into wheat has relied on the exploitation of the ph1b mutant, located on the long arm of chromosome 5B. This mutation allows homologous recombination to occur between chromosomes from related but different genomes, e.g. between the chromosomes of wheat and related chromosomes from a wild relative resulting in the generation of interspecific recombinant chromosomes. However, the ph1b mutant also enables recombination to occur between the homologous genomes of wheat, e.g. A/B, A/D, B/D, resulting in the generation of wheat intergenomic recombinant chromosomes. In this work we report on the presence of wheat intergenomic recombinants in the genomic background of hexaploid wheat/Amblyopyrum muticum introgression lines. The transfer of genomic rearrangements involving the D-genome through pentaploid crosses provides a strategy by which the D-genome of wheat can be introgressed into durum wheat. Hence, a pentaploid crossing strategy was used to transfer D-genome segments, introgressed with either the A- and/or the B-genome, into the tetraploid background of two durum wheat genotypes Karim and Om Rabi 5 in either the presence or absence of different Am. muticum (2n = 2x = 14, TT) introgressions. Introgressions were monitored in backcross generations to the durum wheat parents via multi-color genomic in situ hybridization (mc-GISH). Tetraploid lines carrying homozygous D-genome introgressions, as well as simultaneous homozygous D- and T-genome introgressions, were developed. Introgression lines were characterized via Kompetitive Allele-Specific PCR (KASP) markers and multi-color fluorescence in situ hybridization (FISH). Results showed that new wheat sub-genomic translocations were generated at each generation in progeny that carried any Am. muticum chromosome introgression irrespective of the linkage group that the segment was derived from. The highest frequencies of homologous recombination were observed between the A- and the D-genomes. Results indicated that the genotype Karim had a higher tolerance to genomic rearrangements and T-genome introgressions compared to Om Rabi 5. This indicates the importance of the selection of the parental genotype when attempting to transfer/develop introgressions into durum wheat from pentaploid crosses.

Characterization of the Durum Wheat-Aegilops tauschii 4D(4B) Disomic Substitution Line YL-443 With Superior Characteristics of High Yielding and Stripe Rust Resistance

“…Chromosomes 4T-b and 4H ch from Am. muticum or H. chilense were also transferred into durum wheat, resulting in the development of 4T-b(4B) and 4H ch (4B) disomic substitution lines, respectively (Calderón et al, 2012 ; Othmeni et al, 2019 ).…”

“…Despite its lower planting area compared with hexaploid wheat, the global durum wheat production has been forecast up to 42.7 million tons (MT) in 2020–2021 (Agriculture Agri-Food Canada, 2021 ). About 75% of the global durum wheat production is contributed by the Mediterranean region (Othmeni et al, 2019 ), where crops are mainly grown under environmental (high temperature, drought, and salinity) and biotic (pests and diseases) stresses (Tidiane Sall et al, 2019 ). In China, durum wheat cultivation was first started in the 1970s using varieties introduced from European countries such as Italy (Zhao et al, 2002 ).…”

“…Calderón et al ( 2012 ) successfully developed durum wheat- Hordeum chilense introgression lines by crossing a CS 4H ch (4B) substitution line with a LDN 4D(4B) substitution line, which may contain Septoria tritici blotch resistance and salt tolerance gene. In order to transfer abiotic stress and disease resistance genes from Amblyopyrum muticum into durum wheat, Othmeni et al ( 2019 ) utilized bread wheat/ Am. muticum hybrids to cross with durum wheat, resulting in D-genome and/or T-genome segment introgression lines.…”

Development of Wheat-Aegilops caudata Introgression Lines and Their Characterization Using Genome-Specific KASP Markers

“…For each KASP TM assay, two allele-specific primers and one common primer were used ( Supplementary Table S1). Genotyping reactions were performed as described in Othmeni et al (2019) using a ProFlex PCR system (Applied Biosystems by Life Technology). A final reaction volume of 5 µl was used which included 1 ng genomic DNA, 2.5 µl KASP reaction mix (ROX), 0.068 µl primer mix and 2.43 µl nuclease free water.…”

Homologous chromosome associations in domains before meiosis could facilitate chromosome recognition and pairing in wheat

“…In situ hybridization easily enables the visualization of chromosomal introgressions from one genome into another using labelled genomic DNA from the donor species as probe. Previous studies have showed the identification of the genome of related species by chromosomal introgression lines using FISH or GISH in a wheat genetic background 15 – 17 . In addition to wheat, these cytogenetic studies are possible in other species 18 – 20 .…”