title: Cytogenetic analysis of plants regenerated from colchicine-treated callus cultures of an interspecific Hordeum hybrid.
abstract: Hybrids of Hordeum vulgare (HV) x H. jubatum (HJ) were synthesized for purposes of introgressive breeding, but were sterile and the recovery of pure diploid tillers by colchicine applications in vivo was difficult. Plant regeneration from colchicine-treated callus cultures of the hybrid (HV x HJ) was investigated as a means to produce high numbers of pure diploid, fertile intermediates. 10 of 50 plants regenerated in this manner exhibited variable chromosome numbers with means of approximately 37 (expected diploid number = 42). Cytological examinations of microsporogenesis in all such plants revealed a high incidence of bivalent formation at metaphase I (as compared to nearly complete asynapsis in the F1), but spindle and chromosome abnormalities in later meiotic stages led to complete sterility. Approximately 40% of HJ plants regenerated from colchicine-treated calli appeared to be pure tetraploids of high fertility. These techniques are hence useful for high frequency production of diploid or polyploid plants.
authors.affiliation: Department of Crop and Soil Sciences Michigan, State University, East Laming, Michigan, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Orton
authors.forename: R P
authors.initials: RP
authors.lastname: Steidl