PLANT-REGENERATION FROM ST AUGUSTINEGRASS IMMATURE EMBRYO-DERIVED CALLUS

Development of efficient methods for plant regeneration from callus br oadens the opportunities for genetic manipulation of new turfgrass sel ections through tissue culture. This study was conducted to induce cal lus formation and plant regeneration from embryo explants of St. Augus tinegrass [Stenotaphrum secundatum (Walt.) Kuntze 'Texas Common']. Imm ature embryo explants incubated in the dark produced yellow, amorphous callus on Murashige and Skoog (MS) agar-solidified medium with 30 g L (-1) sucrose and 1 or 5 mg L(-1) dichlo rophenoxyacetic acid (2,4 D). Subculture to medium with 0.25 mg L(-1) 2,4-D and 0.5 mg L(-1) kinetin and introduction of a 14-h photoperiod under fluorescent lamps (16 mu mol m(-2) s(-1) photosynthetic photon flux [PPF]) induced formation o f white, friable, embryogenic callus. Scanning electronic microscopy r evealed that plants regenerated via somatic embryogenesis. Complete pl ant regeneration was achieved from 33% of the original explants after transfer to 0.5 x MS medium without growth regulators. These rooted pl antlets were transplanted to a soil mix in the glasshouse with 100% ac climation success. This system for efficient regeneration of St. Augus tinegrass from callus could be applied to improved cultivar selection after environmental stress testing at the cell level.