Development and Characterization of Wheat-Rye Hybrids Produced by Meiotic Restitution

Karyotype Reorganization in Wheat–Rye Hybrids Obtained via Unreduced Gametes: Is There a Limit to the Chromosome Number in Triticale?

“…The long arms 2RL2RL were preserved in the F 3 generation [69] and were eliminated by F 5 . One reason for the absence of rye chromosomes from F 2 might be their elimination in hybrid embryogenesis [69]. Alien chromosome elimination has been reported in crosses of wheat with Secale cereale, species of genus Hordeum, and species more distantly related to wheat, such as maize (Zea mays), pearl millet (Pennisetum glaucum), sorghum (Sorghum bicolor), and Imperata cylindrica [83][84][85][86][87][88][89][90][91][92][93][94][95][96][97].…”

“…They retained 37 to 40 wheat chromosomes and eliminated four to five rye chromosome pairs. The F 2 hybrid 7-4, the ancestor of the F 5 of Group 2, comprised a set of 46 chromosomes, with 40 wheat and 6 rye chromosomes (1R1R4R4R2RL2RL), as shown by C-banding [69]. The long arms 2RL2RL were preserved in the F 3 generation [69] and were eliminated by F 5 .…”

“…The F 2 hybrid 7-4, the ancestor of the F 5 of Group 2, comprised a set of 46 chromosomes, with 40 wheat and 6 rye chromosomes (1R1R4R4R2RL2RL), as shown by C-banding [69]. The long arms 2RL2RL were preserved in the F 3 generation [69] and were eliminated by F 5 . One reason for the absence of rye chromosomes from F 2 might be their elimination in hybrid embryogenesis [69].…”

“…Thus, the conservation of chromosome sets of the parental subgenomes in octoploid triticale over generations may be associated with the increased expression of rye centromeric histone CENH3 variants in the new genomic environment [108] Unexpectedly, we detected the preservation of rye 4R chromosomes in a monosomic or disomic state up until generation F 5 . While in F 2 , the chromosome pair 4R4R only supplemented the wheat chromosome set [69], in F 5 , 4R4R was added to wheat chromosomes in 58.59% of plants and replaced chromosomes of the fourth homeologous group in 13.15% of plants, which implies its compensational and competitive activity in a new genomic environment. The short arm of chromosome 4R is known to be homeologous to wheat chromosome arms 4BS and 4DS, and partially homeologous to chromosome arm 4AL [109], which is itself involved in evolutionary translocations between chromosome arms 4AL, 5AL, and 7BS [37,39].…”

“…Saratovskaya 29 × Secale cereale L. var. Onochoyskaya (S29 × R) hybrid revealed 56 chromosomes; among them were 42 wheat chromosomes and 14 rye chromosomes [69]. The karyotype of the F 2 1Rv(1A) × R hybrid contained 46 chromosomes, of which three pairs of rye chromosomes 1R1R4R4R2RL2RL, 1R1R replaced the chromosomes 1A1A, and 2RL2RL and 4R4R were added.…”