¹Institute of Evolution, Haifa University, Mt. Carmel, Haifa, 31905 Israel

Correspondence: Alexander Belyayev, E-mail: belyayev@research.haifa.ac.il

Received 15 November 1999; Accepted 27 February 2001.

Abstract

Simultaneous genomic in situ hybridization (GISH) with probe preannealing was used to detect the relationship between chromosomal position and sequence conservation on Aegilops speltoides var. aucheri chromosomes. DNA of Secale sylvestre, Hordeum spontaneum, Festuca pratensis, Semiarundinaria fastuosa, Arundo donax and Zea mays that represent several main groups of Poaceae were used as probes. Different GISH-banding patterns that characterize diverse evolutionary trajectories in the repetitive DNA fraction and correlate with evolutionary distance between tested species were observed. Fast-evolving sequences were detected in subterminal telomeric and subtelomeric heterochromatic regions, whereas sequences in pericentromeric regions showed high levels of conservation. GISH experiments revealed extensive conservation in NOR regions on chromosomes 1 and 6 which, in fact, appears to be a complicated mix of rDNA clusters and heterochromatin blocks of different nucleotide composition.