Institute of Experimental Botany AS CR
We are Discovering the Plant World

Said M., Cabrera A., Vrána J., Číhalíková J., Doležel J.
Plant Molecular Cytogenetics in Genomic and Postgenomic Era Conference. 23-24 September | Katowice-Poland : 91-91, 2014

Keywords: Agropyron cristatum, Karyotype, Flow karyotype
Abstract: Background: The genus Agropyron, which belongs to tribe Triticeae, comprises a number of species that may provide novel genes for wheat improvement. Agropyron cristatum L. (Gaertn.) is a perennial species of economic importance as forage; it is facultatively allogamic and auto-compatible, showing high crossability with other members of Triticeae. A detailed knowledge of its karyotype is a prerequisite for the identification of chromosomes introgressed into wheat. Results: We have analyzed the karyotype of a tetraploid A. cristatum (2n=4x=28, PPPP) accession PI222957 from Iran. Fluorescence in situ hybridization (FISH) with a set of probes showed specific patterns for the majority of homologous chromosome groups. However, variability in the number and position of FISH signals were observed for some homologues in different individuals. The probe pHvG39 containing GAA satellite sequence showed a large signal in the subterminal region of the long arm of one homologous pair, while the 5S rDNA probe showed two to four sites of hybridization. The repetitive sequence pAs1 showed signals mostly in the terminal regions of all chromosomes and it could be used to identify the individual homologous pairs. The terminal location of the pSc119.2 sequence was also detected on ten to fourteen chromosomes. In situ hybridization with the 45S rDNA probe revealed eight hybridization sites, located in the terminal position of the short arms of four chromosome pairs. The flow karyotype of A. cristatum consists of three peaks representing twenty eight chromosomes of the species. Chromosome composition of individual peaks is being determined in ongoing experiments Conclusions: The results of this work support the view that the tetraploid A. cristatum accession has a non-autoploid nature and that the four P genomes have differed by structural changes like reciprocal translocations. Hence this accession could be a segmental allopolyploid. Variability in the number and position of pSc119.2 and 5S signals, and pAs1 patterns, can help to identify chromosomes involved in the structural changes. According to their relative DNA content, chromosomes of A. cristatum were classified into three groups by flow cytometric analysis. A possibility to purify individual chromosomes is being evaluated. More work is needed to characterize the four P genomes in the tetrapod accession, and the first step towards this goal is to establish the karyotype of a diploid A. cristatum. IEB authors: Jarmila Číhalíková, Jaroslav Doležel, Mahmoud Said, Jan Vrána