Trisomics in diploid alfalfa

Abstract

Eight triploids were produced by pollinating male sterile alfalfa tetraploids with diploid lines of closely related “species” involving Medicago sativa, M. falcata and M. coerulea. Seeds were produced on all but one of the triploids by crossing them with diploid and tetraploid lines. Primary trisomic plants were obtained from the crosses with diploid lines and studies on their fertility and trisomic transmission are reported. A brief review of the cytogenetic evidence indicates that the closely related “species” involved in these trisomics appear to be forms of a single polymorphic species and that cultivated tetraploid alfalfa behaves essentially as an autotetraploid. Thus, it is proposed that linkage groups established with these diploid trisomics will also represent the linkage groups of cultivated alfalfa.