REPEATED DNA-SEQUENCES ISOLATED BY MICRODISSECTION .2. COMPARATIVE-ANALYSIS IN HORDEUM-VULGARE AND TRITICUM-AESTIVUM

The genomic organization of two satellite DNA sequences, pHvMWG2314 an d pHvMWG2315, of barley (Hordeum vulgare, 2n=14, HH) was studied by co mparative in Situ hybridization (ISH) and PCR analysis. Both sequences are members of different RsaI families. The sequence pHvMWG2314 is a new satellite element with a monomer unit of 73 bp which is moderately amplified in different grasses and occurs in interstitial clusters on D-genome chromosomes of hexaploid wheat (Triticum aestivum, 2n=42, AA BBDD). The 331-6p monomer pHVMWG2315 belongs to a tandemly amplified r epetitive sequence family that is present in the Poaceae and preferent ially amplified in Aegilops squarrosa (2n=14, DD), H. vulgare and Agro pyron elongatum. (2n=14,EE). The first described representative of thi s family was pAs1 from Ae. squarrosa. Different sequences of one satel lite DNA family were amplified from Ae. squarrosa, A. elongatum and H. vulgare using PCR. Characteristic differences between members of the D and H genome occurred in a variable region which is flanked by two c onserved segments. The heterogeneity within this element was exploited for tile cytogenetic analysis of Triticeae genomes and chromosomes. C omparative ISH with pHvMWG2315 identified individual wheat and barley chromosomes under low (75%) and high (85%) hybridization stringency in homologous and heterologous systems. We propose the designation Tas33 0 for the Triticeae amplified sequence (Tas) satellite family with a 3 30 bp average monomer length.