Development and molecular cytogenetic characterization of Thinopyrum bessarabicum introgression lines in hexaploid...

A variety of Thinopyrum bessarabicum introgressions in both hexaploid and tetraploid wheats were generated and characterized by molecular cytogenetic analysis. Six wheat-J genome recombinants were identified with ND-FISH and GISH. Diploid wheatgrass, Thinopyrum bessarabicum (2n = 2x = 14, E^bE^b or J^bJ^b or JJ), is a well-known alien source of salinity tolerance and disease resistance for wheat improvement. The true genetic potential and effect of such introgressions into wheat can be best studied in chromosomal addition or substitution lines. Here, we report the generation and characterization of various categories of Th. bessarabicum derivatives in both hexaploid and tetraploid cultivated wheats. Sequential non-denaturing fluorescence in situ hybridization (ND-FISH) and genomic in situ hybridization (GISH) are robust techniques to visualize the size of alien introgressions and breakpoints. We identified a complete set of monosomic addition lines into both bread wheat and durum wheat, except for 7J in durum wheat, by sequential ND-FISH and GISH. We also characterized alien derivatives belonging to various classes including mono-telosomic additions, disomic additions, monosomic substitutions, double monosomic substitutions, monosomic substitution-monosomic additions, double monosomic additions, and multiple monosomic additions into both bread and durum wheats. In addition, various wheat-Th. bessarabicum recombinant chromosomes were also detected in six alien derivatives. These wheat-Th. bessarabicum derivatives will provide useful cytogenetic resources for improvement of both hexaploid and tetraploid wheats.