AUTHOR=Said Mahmoud , Cápal Petr , Farkas András , Gaál Eszter , Ivanizs László , Friebe Bernd , Doležel Jaroslav , Molnár István 

TITLE=Flow karyotyping of wheat-Aegilops additions facilitate dissecting the genomes of Ae. biuncialis and Ae. geniculata into individual chromosomes

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1017958

DOI=10.3389/fpls.2022.1017958

ISSN=1664-462X

ABSTRACT=<p>Breeding of wheat adapted to new climatic conditions and resistant to diseases and pests is hindered by a limited gene pool due to domestication and thousands of years of human selection. Annual goatgrasses (<italic>Aegilops</italic> spp.) with M and U genomes are potential sources of the missing genes and alleles. Development of alien introgression lines of wheat may be facilitated by the knowledge of DNA sequences of <italic>Aegilops</italic> chromosomes. As the <italic>Aegilops</italic> genomes are complex, sequencing relevant <italic>Aegilops</italic> chromosomes purified by flow cytometric sorting offers an attractive route forward. The present study extends the potential of chromosome genomics to allotetraploid <italic>Ae. biuncialis</italic> and <italic>Ae. geniculata</italic> by dissecting their M and U genomes into individual chromosomes. Hybridization of FITC-conjugated GAA oligonucleotide probe to chromosomes suspensions of the two species allowed the application of bivariate flow karyotyping and sorting some individual chromosomes. Bivariate flow karyotype FITC vs. DAPI of <italic>Ae. biuncialis</italic> consisted of nine chromosome-populations, but their chromosome content determined by microscopic analysis of flow sorted chromosomes indicated that only 7M<sup>b</sup> and 1U<sup>b</sup> could be sorted at high purity. In the case of <italic>Ae. geniculata</italic>, fourteen chromosome-populations were discriminated, allowing the separation of nine individual chromosomes (1M<sup>g</sup>, 3M<sup>g</sup>, 5M<sup>g</sup>, 6M<sup>g</sup>, 7M<sup>g</sup>, 1U<sup>g</sup>, 3U<sup>g</sup>, 6U<sup>g</sup>, and 7U<sup>g</sup>) out of the 14. To sort the remaining chromosomes, a partial set of wheat<italic>-Ae. biuncialis</italic> and a whole set of wheat-<italic>Ae. geniculata</italic> chromosome addition lines were also flow karyotyped, revealing clear separation of the GAA-rich <italic>Aegilops</italic> chromosomes from the GAA-poor A- and D-genome chromosomes of wheat. All of the alien chromosomes represented by individual addition lines could be isolated at purities ranging from 74.5% to 96.6% and from 87.8% to 97.7%, respectively. Differences in flow karyotypes between <italic>Ae. biuncialis</italic> and <italic>Ae. geniculata</italic> were analyzed and discussed. Chromosome-specific genomic resources will facilitate gene cloning and the development of molecular tools to support alien introgression breeding of wheat.</p>