Genomic Distribution of a Long Terminal Repeat (LTR) Sabrina-like Retrotransposon in Triticeae Species

Knowledge of the chromosomal distribution of long terminal repeats (LTR) is important for understanding plant chromosome structure, genomic organization and evolution, as well as providing chromosomal landmarks that are useful for chromosome engineering. The aim of this study is to investigate the genomic distribution of Sabrina-like LTR pDbH12, which was first isolated from Dasypyrum breviaristatum (V-b genome), on Triticeae species in relation to the genomic evolution and chromosome identification. Fluorescence in situ hybridization ( FISH) analysis showed that pDbH12 is present on Dasypyrum ( V genome) and Hordeum ( H genome) species with the hybridized signals covering the entire chromosomes. However, clone pDbH12 did not hybridize to the genomes of Secale, Triticum, Lophopyrum, Pseduoroengeria, Aegilops, Agropyron desertorum and Elymus. Thinopyrum intermedium displayed fourteen chromosomes that hybridized with pDbH12. Sequential FISH identified these chromosomes as belonging to the J(s) genome. Results from sequence characterized amplified region ( SCAR) marker and dot blot both support the FISH results, and the integrative results suggest that amplification of Sabrina-like LTR retrotransposons is an important factor which involved in the speciation process. Clone pDbH12 could serve as a cytogenetic marker for tracing chromatin from V or V-b, H and J(s) genomes in wheat-alien introgression lines.