Development and characterization of small translocations between the Pm13 introgression from Aegilops longissima and wheat homoeologous A, B and D chromosomes.

Background: Wild relatives have substantial impacts on the resistance of wheat to biotic and abiotic stresses. The genetic diversity of these wild varieties can be employed to widen the wheat gene pool by introducing wild allele introgression and genome structure variations. The powdery mildew resistance gene Pm13 was derived from the wheat wild relative species Aegilops longissima (SS, 2n = 2x = 14) and was transferred into wheat chromosome 3BS over 30 years.

Non-B-form DNA is associated with centromere stability in newly-formed polyploid wheat.

Non-B-form DNA differs from the classic B-DNA double helix structure and plays a crucial regulatory role in replication and transcription. However, the role of non-B-form DNA in centromeres, especially in polyploid wheat, remains elusive. Here, we systematically analyzed seven non-B-form DNA motif profiles (A-phased DNA repeat, direct repeat, G-quadruplex, inverted repeat, mirror repeat, short tandem repeat, and Z-DNA) in hexaploid wheat.

Cytological analysis of the diploid-like inheritance of newly synthesized allotetraploid wheat.

Polyploidization is a process which is related to species hybridization and whole genome duplication. It is widespread among angiosperm evolution and is essential for speciation and diversification. Allopolyploidization is mainly derived from interspecific hybridization and is believed to pose chromosome imbalances and genome instability caused by meiotic irregularity.

New insights on the evolution of nucleolar dominance in newly resynthesized hexaploid wheat Triticum zhukovskyi.

Nucleolar dominance (ND) is a widespread epigenetic phenomenon in hybridizations where nucleolus transcription fails at the nucleolus organizer region (NOR). However, the dynamics of NORs during the formation of Triticum zhukovskyi (GGA A A A ), another evolutionary branch of allohexaploid wheat, remains poorly understood. Here, we elucidated genetic and epigenetic changes occurring at the NOR loci within the A , G, and D subgenomes during allopolyploidization by synthesizing hexaploid wheat GGA A A A and GGA A DD.

Chromosome Stability of Synthetic-Natural Wheat Hybrids.

Primary allopolyploids are not only ideal materials to study species evolution, but also important bridges in incorporating genetic diversity of wild species into crops. Primary allopolyploids typically exhibit chromosome instability that a disadvantage trait in crop breeding. Newly synthesized hexaploid wheat has been widely used in wheat genetics and breeding studies.

Some characteristics of crossing over in induced recombination between chromosomes of wheat and rye.

Allopolyploid wheat (Triticum aestivum L.) carries three pairs of homoeologous genomes but its meiotic pairing is diploid-like. This is the effect of the Ph (pairing homoeologous) system which restricts chromosome pairing to strictly homologous.

Genetic mapping of a major QTL promoting homoeologous chromosome pairing in a wheat landrace.

Common wheat landrace Kaixian-luohanmai carries a gene(s) that promotes homoeologous chromosome pairing. A major QTL responsible for this effect was mapped to chromosome arm 3AL. Polyhaploid hybrids of a Chinese common wheat landrace Kaixian-luohanmai (KL) and related species show increased levels of chromosome pairing.

Instability of Alien Chromosome Introgressions in Wheat Associated with Improper Positioning in the Nucleus.

Alien introgressions introduce beneficial alleles into existing crops and hence, are widely used in plant breeding. Generally, introgressed alien chromosomes show reduced meiotic pairing relative to the host genome, and may be eliminated over generations. Reduced pairing appears to result from a failure of some telomeres of alien chromosomes to incorporate into the leptotene bouquet at the onset of meiosis, thereby preventing chiasmate pairing.

Introgression of Powdery Mildew Resistance Gene on Rye Chromosome Arm 6RS Into Wheat.

Powdery mildew, caused by the fungus f. sp. , represents a yield constraint in many parts of the world.