|Ivic, Snezana - USDA ARS BELTSVILL MD|
Submitted to: American Society of Sugarbeet Technologists
Publication Type: Abstract Only
Publication Acceptance Date: December 28, 2000
Publication Date: N/A
Technical Abstract: Alternative sources of embryogenic sugar beet callus were explored in order to improve and optimize the particle bombardment method (Synder et al. 1999) for introduction of beneficial foreign genes into sugar beet. Biolistic transformation of embryogenic hypocotyl sugar beet callus requires long seed germination and hypocotyl cultivation periods. Transformation frequencies obtained with hypocotyls from a noncommercial line, REL-1, were low. Leaf discs taken from several individuals of 6 different germplasms were screened for callus-forming ability and shoot regeneration. Discs were excised from greenhouse-grown plants and cultured on MS basal medium with 1 mg 1-1 BAP (Doley and Saunders, 1989) at different temperature regimes in the dark. Breeding line FC 607 (Smith and Ruppel, 1980) was superior in its ability to form regenerative callus at 30oC after 5 weeks. This callus was used to initiate suspension cultures, which when plated, regenerated both shoots and somatic embryos after 4 weeks. Suspension cultures have the advantage of consisting of small cell clumps and individual cells, decreasing the chance of generating chimeras using the particle bombardment method. In addition, somatic embryos are easier to root than adventitious shoots and usually a larger percentage of them develop into normal plantlets. Use of both leaf disc callus and suspension cultures with the particle bombardment method is expected to increase the overall frequency of regeneration of transgenic sugar beet plants.