The allotetraploid (UUMM) species Aegilops geniculata and Ae. biuncialis are closely related to wheat and considered as sources of gene for stress resistance and grain nutritional value. Both species have higher contents of protein and ß glucan and higher proportions of water-soluble (WE)-pentosans relative to wheat. Analyses of wheat addition lines showed increased ß-glucan content associated with chromosomes 5Ug, 7Ug and 7Mb, while chromosomes 1Ub and 1Mg affected the proportion of polymeric proteins in wheat. In order to identify Aegilops homologs of the key genes responsible for the biosynthesis of storage proteins, ß -glucan and pentosan (arabinoxylan=AX), a sequence similarity search was made between the genomes of wheat or barley and the Aegilops genomes. Because complete sequences of the U- and M-genomes are not available, flow-sorted chromosomes of Ae. umbellulata (UU) were sequenced and were used for comparative analysis (http://olomouc.ueb.cas.cz/projects/Aegilops_umbellulata). The BLASTn search showed that the key genes responsible for wheat grain storage proteins (HMW and LMW glutenin subunits, γ-gliadins) were assigned to the same homeologous group chromosomes (group 1) in the U-genome of Ae. umbellulata as in bread wheat. The α-gliadin genes, which are assigned to group 6 chromosomes in wheat, were located on the 1U and 3U chromosomes of Aegilops. The genes involved in ß -glucan biosynthesis (OsCslF1-F2, HvCslF3-4, HvCslF6-10, HvCslF12-13, HvCslH1) in Aegilops homologs were also assigned to the same homeologouos group chromosomes (group 1, 2, 5, 7) as in wheat. The same was found for most of the genes responsible for AX biosynthesis, which were assigned to group 4 or 7 chromosomes (TaGT43 family), group 3 chromosomes (TaGT47 family), and group 2 chromosomes (TaGT75 family). However, some homologues were found on different chromosomes to those in wheat. For example, gene TaGT47-12 was assigned to the group 3 chromosomes of wheat, while its Aegilops homolog was present on chromosome 6U. Differences in chromosomal assignments were also found for genes HvCslF11, TaGT61-1, TaGT61-2 and TaGT75-4. The chromosomal assignment of genes influencing grain ß -glucan and AX content in Aegilops orthologs provides a foundation for further genome-wide association studies to identify QTL responsible for the amount and composition of dietary fiber in these Aegilops. The study will therefore contribute to the more efficient use of wild wheat relatives for introgression in wheat breeding programs to develop wheat varieties with increased fibre content, especially ß -glucan, and improved health benefits.

Acknowledgement. Funded by projects GINOP-2.3.2-15-2016-00029, K112169, K116277, János Bolyai (MR) and Marie Curie Fellowships (H2020-MSCA-IF-2016-746253) (IM).