Development of DNA markers from physically mapped loci in Aegilops comosa and Aegilops umbellulata using single-gene FISH and chromosome sequences

Said M., Holušová K., Farkas A., Ivanizs L., Gaál E., Cápal P., Abrouk M., Martis-Thiele M., Kalapos B., Bartoš J., Friebe B., Doležel J. and Molnár I.
Book of Abstracts - Cytogenetics Meeting 2021- Chromosome Biology in context of Evolution and Plant Breeding - September 27-28 - Görlitz - Germany : , 2021

Keywords: goat grasses, Aegilops comosa, Aegilops umbellulata, single-gene FISH, chromosome flow sorting and sequencing, chromosome rearrangements, homoeologous relationships, molecular markers
Abstract: During the evolution of Aegilops and Triticum grass genera, diversification of D-genome lineage resulted in the formation of diploid C, M and U genomes of Aegilops. The extent of structural genome alterations, which accompanied their evolution and speciation, and which may negatively affect gene transfer into wheat, remains unknown. Using fluorescence in situ hybridization (FISH), chromosome positions of forty-three ortholog genes were mapped on M- and U-genome progenitors Ae. comosa and Ae. umbellulata, respectively. The single-gene FISH maps were used to investigate the chromosome structure and describe the synteny of wheat, Aegilops M, U and C genomes. Chromosomes of Ae. comosa preserved collinearity with wheat, excluding chromosome 2M with intrachromosomal rearrangements and paracentric inversion in 6ML. While Ae. umbellulata chromosomes 1U, 3U and 5U maintained collinearity with wheat, structural reorganizations in 4U, 6U and 7U suggested similarity with C genome of Ae. markgrafii. To develop molecular markers, the single-gene FISH data were validated in silico using DNA sequence assemblies from flow-sorted M- and U-genome chromosomes. The sequence similarity search confirmed 44 out of 47 single-gene loci in Ae. comosa and 40 out of 52 map positions in Ae. umbellulata. Polymorphic regions thus identified enabled development of molecular markers, which were PCR validated using wheat-Aegilops chromosome addition lines. The single-gene FISH-based approach allowed development of PCR markers specific for cytogenetically mapped positions on Aegilops chromosomes, substituting as yet unavailable segregating map. The new knowledge and resources will support the efforts to introgress Aegilops genes into wheat and also their cloning.
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IEB authors: Jan Bartoš, Petr Cápal, Jaroslav Doležel, Kateřina Holušová, Istvan Molnar, Mahmoud Said