Widening the genepool of bread wheat by dissection of added Agropyron cristatum chromosomes 5P and 6P using gametocidal system

Gaál E., Said M., Copete A., Cabrera A., Cápál C., Szakács E., Farkas A., Ivanizs L., Türkösi E., Endo T., Doležel J., Molnár I.
Book of Abstracts - 6th Conference on Cereal Biotechnology and Breeding - EUCARPIA - November 3-5. Budapest - Hungary : , 2021

Keywords: Agropyron cristatum, COS marker, genome analysis, translocations
Abstract: Widening the gene pool of bread wheat (Triticum aestivum) by employing its wild relatives as donors of new alleles and genes will ensure the ability of wheat to sustain yield quantity under adverse environmental conditions. The chromosomes of Agropyron cristatum (PPPP) represent a rich source of agronomically important genes providing resistance to rust diseases, tolerance to drought and salinity and they positively affect the yield quantity. In order to transfer the useful agronomic traits to wheat, wheat – A. cristatum chromosome addition lines 1P-6P have been previously developed via interspecific hybridization. However, only low number of wheat-A. cristatum translocation lines were produced. Gametocidal (Gc) genes induce chromosomal rearrangements in gametes lacking them in the monosomic addition of the Gc chromosome. These Gc genes acts like a biological mutagen in common wheat and used as an efficient approach to produce wheat-alien chromosome rearrangements. However, the utilization of wild genetic diversity has been hampered by low throughput of selection methods and the lack of knowledge on the genomes of wild relatives. The COS (Conserved Orthologous Set) markers specific for genes conserved throughout evolution define orthologous regions, thus enabling the comparison of regions on the chromosomes of related species. In this study, the wheat-CS (Chinese Spring)-A. cristatum 5P and 6P disomic addition lines were crossed with CS-Ae. cylindrica 2C addition line with gametocidal effect to induce structural rearrangements between the chromosomes of wheat and 5P or 6P by the Gc system. GISH and FISH analysis of the BC1 F2 lines detected seven and two wheat-Agropyron structural rearangements for chromosomes 5P and 6P, respectively. Three 5P-wheat and one translocation involving the chromosome 6P were successfully transferred to the next generation. The morphological investigation of the selfed progenies indicated the 5P chromosome introgressions affected positively to the grain number per plant and the fertility relative to the wheat parental line. We used wheat–A. cristatum 1P-6P disomic chromosome and ditelosome addition lines to map COS markers on Agropyron chromosomes and characterize syntenic relationships between tetraploid A. cristatum and bread wheat. Out of 328 tested markers, 139 were polymorphic between tetraploid crested wheatgrass and wheat. Sixty-nine markers were located on the chromosomes 1P–6P in wheat, ranging from 6 to 17 markers per chromosome. BLASTn of the source ESTs resulted in significant hits for 67 markers on the wheat pseudomolecules. Generally, COS markers of the same homeologous group were detected on similar arms in both Agropyron and wheat. However, some intragenomic duplications and chromosome rearrangements were detected in tetraploid A. cristatum. These results provide new insights into the structure and evolution of the tetraploid A. cristatum genome and will facilitate the exploitation of this Triticeae species for introgression breeding of bread wheat. Acknowledgments This research was funded by Hungarian National Research, Development and Innovation Office (http://nkfih.gov.hu/english) (OTKA K135057) to IM. Grant award RTI2018-093367-B-I00 from the Spanish State Research Agency (Ministry of Science, Innovation and Universities), co-financed by the European Regional Development Fund (FEDER) from the European Union.
DOI: IEB authors: Petr Cápal, Jaroslav Doležel, Istvan Molnar, Mahmoud Said