Callus induction and plant regeneration from mature bluegrass (Poa pratensis L.) seeds

A protocol was discussed for high efficient plant regeneration from seven bluegrass (Poa pratensis L.) cultivars via an indirect callus induction and somatic embryogenesis method. Mature seeds were used as explants for callus initiation. Callus induction and proliferation efficiencies were investigated on NB, modified MS (MMS) and MS media, supplemented with 2.0 mg·L^-1 2,4-dichlorophenoxyacetic acid (2,4-D). The MMS medium performed best. Based on the MMS medium, direct and indirect callus induction effects of bluegrass from mature seeds were compared at the range of 1-5 mg·L^-1 2,4-D contained in the medium. Under the direct callus induction method, the most suitable 2,4-D concentrations varied among cultivars. Under the indirect callus induction method, a significantly high callus induction frequency (93.33%-98.33%) was obtained and there were barely any statistically significant differences among the tested genetically diverse cultivars. Somatic embryos were promoted on the MMS medium supplemented with 3 mg·L^-1 2,4-D, 0.1 mg·L^-1 kinetin and 0.8 mg·L^-1 CuSO₄. Embryogenetic calli developed into plantlets on the MMS medium containing different concentrations of thidiazuron (TDZ), and the differentiation frequencies varied in the range from 20.15% to 77.65%. The 0.25 mg·L^-1 TDZ was generally the most suitable concentration for the tested cultivars.