Callus induction and haploid plant regeneration from anther culture of two poplar species

Anthers from 5 different clones of Populus nigra and Populus deltoides were isolated from dormant flower buds before catkin elongation and exposition, in order to establish haploid and doubled haploid poplar plants in vitro. Isolated anthers were cold treated and placed on MS medium supplemented with 2,4-D (0.5 mg/l to 2.0 mg/l) and Kinetin (0.1 mg/l to 1.0 mg/l). The optimal hormone concentration for callus induction was 1.0 mg/l of 2,4-D and 0.1 mg/l of Kinetin. The callus initiation response of the genotypes ranged from 24% to 75%. The genotypes with the best callus initiation response were P. nigra N-90 (59%) and P. deltoides D-29 (75%). Calli were subcultured on MS or WPM medium supplemented with BA (0 mg/l to 2.5 mg/l) and NAA (0 mg/l to 0.2 mg/l) for plant regeneration. The highest shoot regeneration frequency (79%) was obtained after 2 subcultures on MS medium supplemented with BA (1.0 mg/l) and NAA (0.2 mg/l), and on WPM medium supplemented with BA (2.5 mg/l). The rate of shoot regeneration and number of shoots/calli ranged from 4% to 79% and 1 to 9, respectively.