Dihaploids of Elymus from the interspecific crosses E. dolichatherus x E. tibeticus and E. brevipes x E. panormitanus

Dihaploids (n=2x=14, SY) of two Elymus species, i.e., E. dolichatherus (Keng) Löve (2n=4x=28, SSYY) and E. brevipes (Keng) Löve (2n=4x=28, SSYY), were obtained from the interspecific hybrid combinations E. dolichatherus (♀) x E. tibeticus (Meld.) G. Singh (♂) and E. brevipes (♀) x E. panormitanus (Parl.) Tzvelev (♂). The dihaploids were probably formed through selective elimination of male parental chromosomes in early embryo development. Meiotic chromosome behavior was studied in E. dolichatherus, E. brevipes, and their dihaploids. The two parental Elymus species had regular meioses with predominantly ring bivalent formation. A low frequency of homoeologous chromosome pairing was observed, with an average of 0.81 bivalents and 0.03 trivalents in the dihaploid of E. dolichatherus, and 0.26 bivalents in the dihaploid of E. brevipes. Up to two chromatid bridges accompanied by small fragments were present at anaphase I of the E. dolichatherus dihaploid. It is concluded from this study that: (i) both E. dolichatherus and E. brevipes are allotetraploid species; (ii) a low affinity exists between the "S" and "Y" genomes of the two Elymus species.