Genome Analysis of a Natural Hybrid with 2n = 63 Chromosomes in the Genus Elytrigia Desv. (Poaceae) Using the GISH Technique

Abstract

Genomic in situ hybridization (GISH), using genomic DNA probes from Thinopyrum elongatum (E genome, 2n = 14), Th. bessarabicum (J genome, 2n = 14), Pseudoroegneria stipifolia (S genome, 2n = 14), Agropyron cristatum (P genome, 2n = 28) and Critesion californicum (H genome, 2n = 14), was used to identify the genome constitution of a natural hybrid population morphologically close to Elytrigia pycnantha and with somatic chromosome number of 2n = 63. The GISH results indicated the presence of a chromosomal set more or less closely related to the E, P, S and H genomes. In particular, two sets of 14 chromosomes each showed close affinity to the E genome of Th. elongatum and to the P genome of A. cristatum. However, they included 2 and 10 mosaic chromosomes, respectively, with S genome specific sequences at their centromeric regions. Two additional sets (28 chromosomes) appeared to be very closely related to the S genome of Ps. stipifolia. The last genome involved (7 chromosomes) is related to the H genome of C. californicum but includes one chromosome with S genome-specific sequences around the centromere and two other chromosomes with a short interstitial segment also containing S genome related sequences. On a basis of GISH analysis and literature data, it is hypothesized that the natural 9-ploid hybrid belongs to the genus Elytrigia and results from fertilization of an unreduced gamete (n = 42) of E. pycnantha and a reduced gamete (n = 21) of E. repens. The genomic formula SSSSP^SP^SE^SE^SH^S is proposed to describe its particular genomic and chromosomal composition.

Genomic in situ hybridization - 9-ploid hybrid - genomic analysis - Elytrigia - mosaic chromosomes

References

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Section Editor: F. Salamini