Inheritance of Somatic Embryogenesis in Orchardgrass

The ability for plant tissue to regenerate following in vitro culture is highly dependent on the genotype. The inheritance of somatic embryogenesis in orchardgrass (Dactylis glomerata L.; 2n = 4x = 28) was studied using one embryogenic genotype (Embryogen-P) and random plants from two nonembryogenic populations, Jay and OSG-13. Individual plants from F 1 (Embryogen-P x Jay), F 2 , BC 1 , and test cross (F 1 x OSG-13) matings were evaluated for somatic embryogenesis. Leaf bases were cultured in the dark on SH medium containing 30 μM dicamba (3,6-dichloro-o-anisic add) at 25°C for 4 wk. Qualitative differences of callus quality ranging from undesirable watery and gelatinous to desirable compact, firm, and friable were observed in all segregating populations. The percentage of plants initiating a firm and friable callus was significantly (P < 0.05) correlated to the frequency of embryogenic plants. The segregation ratios observed across all matings indicated that the ability to form somatic embryos from cultures derived from leaf base explants of orchardgrass was conditioned by two independent dominant genes with complementary effects. The genotype of Embryogen-P was simplex/simplex. The simple model of inheritance and the dominance of the character simplifies development of cultivars with improved in vitro response that would facilitate the application of biotechnological techniques in this species.