Comparative FISH mapping of two highly repetitive DNA sequences in Hordeum chilense (Roem. et Schult.)

Abstract

Hordeum chilense Roem. et Schult. (2n = 14) is an autogamous wild barley from Chile and Argentina included in the section Anisolepis Nevski. This species shows interesting agronomic traits that can be incorporated into crop plant species. Hordeum chilense has been successfully crossed with species of the genus Aegilops. Among the amphiploids obtained, the hexaploid tritordeum (2n = 6x = 42, AABBHchHch) is outstanding and shows good agronomic characteristics, suggesting its potential either as a new crop or as a bridge species to introgress interesting traits into cultivated cereals. The aim of the present work was to study the hybridization patterns of the two repetitive DNA probes pAs1 and pSc119.2 to evaluate their utility for the identification of H. chilense chromosomes. Fourteen lines of H. chilense were analyzed with fluorescent in situ hybridization using probes pSc119.2 and pAs1. The probe pAs1 was more widely dispersed than pSc119.2 over the H. chilense (Hch) genome. We found 89 different signals for pAs1, distributed evenly over the whole genome, and 10 for pSc119.2, located mainly over the telomeric regions. Five distinct hybridization signals were found for pAs1 and four distinct signals for pSc119.2. These signals allow the identification of different H. chilense lines. For example, centromeric signals for pAs1 on the short arms of chromosomes 1 and 7 identify line H46, and a telomeric signal for pSc119.2 on the short arm of chromosome 2 identifies line H1. A high degree of polymorphism in the hybridization patterns was found, confirming the extensive variability present in H. chilense. This work provides tools for the identification of H. chilense chromosomes in different genetic backgrounds.