Tissue culture and plant regeneration of blue grama grass, Bouteloua gracilis (H.B.K.) Lag. ex Steud

As a first step towards applying biotechnology to blue grama, Bouteloua gracilis (H.B.K.) Lag. ex Steud., we have developed a regenerable tissue culture system for this grass. Shoot apices were isolated from 3-d-old seedlings and cultured in 15 different growth regulator formulations combining 2,4-dichlorophenoxyacetic acid (2,4-D), Picloram (4-amino-3,5,6-trichloropicolinic acid), N super(6)-benzyladenine (BA) or adenine (6-aminopurine). The highest induction of organogenic callus was obtained with formulations containing 1 mg l super(-1) (4.52 mu M) 2,4-D plus 0.5 mg l super(-1) (2.22 mu M) BA, and 2 mg l super(-1) (8.88 mu M) BA plus 1 mg l super(-1) (4.14 mu M) Picloram with or without 40 mg l super(-1) (296.08 mu M) adenine. Lower frequencies of induction were obtained for embryogenic as compared to organogenic callus. The most efficient treatments for induction of embryogenic callus contained 2 mg l super(-1) (9.05 mu M) 2,4-D combined with 0.25 (1.11 mu M) or 0.50 mg l super(-1) (2.22 mu M) BA, or 1 mg l super(-1) (4.52 mu M) 2,4-D with 0.50 mg l super(-1) (2.22 mu M) BA. Regeneration was achieved in hormonefree Murashige anmd Skoog (MS) medium, half-strength MS medium or MS medium plus 1 mg l super(-1) (1.44 mu M) gibberellic acid. The number of plantlets regenerated per 500 mg callus fresh weight on MS medium ranged from 9 for 2 mg l super(-1) (9.05 mu M) 2,4-D to 62.2 for induction medium containing 2 mg l super(-1) (8.28 mu M) Picloram, 1 mg l super(-1) (4.44 mu M) BA and 40 mg l super(-1) (296.08 mu M) adenine. Regenerated plants grown in soil under greenhouse conditions reached maturity and produced seeds.