SOMATIC EMBRYOGENESIS AND PLANT-REGENERATION FROM CALLUS-CULTURES OF TIFTON-9 BAHIAGRASS

Identifying appropriate tissue culture and plant regeneration systems for agronomically important cultivars is often an important step in de veloping gene introduction techniques. Culture conditions for somatic embryogenesis and plant regeneration of 'Tifton 9' bahiagrass (Paspalu m notatum Fluegge L.) from leaf-stem cross sections are described. Cul tures were initiated and maintained in the dark on Schenk and Hildebra ndt medium containing 3% sucrose and 6.6 mg L(-1) dicamba. Plant regen eration was initiated by transfer of callus tissue to medium lacking d icamba and incubating in continuous light. Scanning electron microscop y demonstrated somatic embryogenesis as the process leading to plantle t formation. More than 96% of 4-mm-diam. callus segments produced plan ts, many with multiple germinating embryos. Approximately 300 plantlet s were produced per gram of calli. Plants could be grown to maturity b y transferring to greenhouse flats 3 wk after placing on regeneration medium. Nonspecific subculturing of primary calli resulted in a declin e in regenerability and an increase in the number of albino regenerate d plants after 4 to 5 mo from the initiation of callus growth on the e xplants. However, subculturing of specific callus cells identified as embryogenic extended the efficiency of regeneration and reduced the fr equency of albino regenerates. Efficiency of regenerating green plants remained essentially unchanged for 10 mo. We have therefore identifie d a tissue culture and plant regeneration system suitable for use in g enetic engineering.