M. Orgaard et K. Anamthawat-jonsson, Genome discrimination by in situ hybridization in Icelandic species of Elymus and Elytrigia (Poaceae : Triticeae), GENOME, 44(2), 2001, pp. 275-283
The genome constitution of Icelandic Elymus caninus, E. alaskanus, and Elyt
rigia repens was examined by fluorescence in situ hybridization using genom
ic DNA and selected cloned sequences as probes. Genomic in situ hybridizati
on (GISH) of Hordeum brachyantherum ssp. californicum (diploid, H genome) p
robe confirmed the presence of an H genome in the two tetraploid Elymus spe
cies and identified its presence in the hexaploid Elytrigia repens. The H c
hromosomes were painted uniformly except for some chromosomes of Elytrigia
repens which showed extended unlabelled pericentromeric and subterminal reg
ions. A mixture of genomic DNA from H. marinum ssp. marinum (diploid,Xa gen
ome) and H. murinum ssp. leporinum (tetraploid,Xu genome) did not hybridize
to chromosomes of the Elymus species or Elytrigia repens, confirming that
these genomes were different from the H genome. The St genomic probe from P
seudoroegneria spicata (diploid) did not discriminate between the genomes o
f the Elymus species, whereas it produced dispersed and spotty hybridizatio
n signals most likely on the two St genomes of Elytrigia repens. Chromosome
s of the two genera Elymus and Elytrigia showed different patterns of hybri
dization with clones pTa71 and pAes41, while clones pTa1 and pSc119.2 hybri
dized only to Elytrigia chromosomes. Based on FISH with these genomic and c
loned probes, the two Elymus species are genomically similar, but they are
evidently different from Elytrigia repens. Therefore the genomes of Iceland
ic Elymus caninus and E. alaskanus remain as StH, whereas the genomes of El
ytrigia repens are proposed as XXH.