Molecular cytogenetic (FISH) and genome analysis of diploid wheatgrasses and their phylogenetic relationship.

This paper reports detailed FISH-based karyotypes for three diploid wheatgrass species Agropyron cristatum (L.) Beauv., Thinopyrum bessarabicum (Savul.&Rayss) A. Löve, Pseudoroegneria spicata (Pursh) A. Löve, the supposed ancestors of hexaploid Thinopyrum intermedium (Host) Barkworth & D.R.Dewey, compiled using DNA repeats and comparative genome analysis based on COS markers. Fluorescence in situ hybridization (FISH) with repetitive DNA probes proved suitable for the identification of individual chromosomes in the diploid JJ, StSt and PP genomes. Of the seven microsatellite markers tested only the (GAA)n trinucleotide sequence was appropriate for use as a single chromosome marker for the P. spicata AS chromosome. Based on COS marker analysis, the phylogenetic relationship between diploid wheatgrasses and the hexaploid bread wheat genomes was established. These findings confirmed that the J and E genomes are in neighbouring clusters

Examples of COS markers resulting in polymorphic PCR products between hexaploid wheat and perennial grasses.

<p>(A) Amplicons produced by the markers <i>c746642</i> and (B) <i>c756279</i> from genomic DNA of wheat genotype GK Öthalom (<i>T</i>. <i>aestivum</i>), <i>T</i>. <i>elongatum</i> MvGB1963, <i>T</i>. <i>bessarabicum</i> MvGB1706, <i>Ps</i>. <i>spicata</i> MvGB1607 and MvGB1615, and <i>A</i>. <i>cristatum</i> MvGB1521 and MvGB1509.</p

Chromosome FISH- karyotype of three diploid wheatgrass species.

<p>Repetitive DNA sequences were used as markers to construct karyotypes: pSc119.2 green, Afa- family red and pTa71 (45S rDNA) orange (pAs1 and HT100.3 not shown) <i>P</i>. <i>spicata</i> accession 362480 chromosomes show repetitive DNA markers pAs1 red and Fat probe green. Arrows indicate positions of NOR loci. Scale bar = 10μm.</p

Original (in brackets) and Martonvásár (MvGB) registration number and country (area) of geographical origin for accessions used for FISH and COS marker analysis.

<p>Accession number 362480 is maintained in Moscow Scientific-Research Agricultural Institute “Nemchinovka”, Russia.</p

DNA repetitive probes and trinucleotide sequences used for FISH karyotyping.

<p>DNA repetitive probes and trinucleotide sequences used for FISH karyotyping.</p

Spike morphology of three representative diploid wheatgrass plants.

<p>All plants were grown under greenhouse conditions in Martonvásár, Hungary (Size marker = 10mm).</p

Molecular cytogenetic (FISH) and genome analysis of diploid wheatgrasses and their phylogenetic relationship

<div><p>This paper reports detailed FISH-based karyotypes for three diploid wheatgrass species <i>Agropyron cristatum</i> (L.) Beauv., <i>Thinopyrum bessarabicum</i> (Savul.&Rayss) A. Löve, <i>Pseudoroegneria spicata</i> (Pursh) A. Löve, the supposed ancestors of hexaploid <i>Thinopyrum intermedium</i> (Host) Barkworth & D.R.Dewey, compiled using DNA repeats and comparative genome analysis based on COS markers. Fluorescence <i>in situ</i> hybridization (FISH) with repetitive DNA probes proved suitable for the identification of individual chromosomes in the diploid JJ, StSt and PP genomes. Of the seven microsatellite markers tested only the (GAA)_n trinucleotide sequence was appropriate for use as a single chromosome marker for the <i>P</i>. <i>spicata</i> A^S chromosome. Based on COS marker analysis, the phylogenetic relationship between diploid wheatgrasses and the hexaploid bread wheat genomes was established. These findings confirmed that the J and E genomes are in neighbouring clusters.</p></div

Dendrogram illustrating genetic similarities between the genera <i>Thinopyrum</i>, <i>Agropyron</i>, <i>Pseudoroegneria</i> and hexaploid wheat.

<p>Dendrogram was generated by UPGMA cluster analysis (Cluster) and calculated from 206 loci produced by 97 COS markers.</p