STABLE TRANSFORMATION OF THE FOOD YAM DIOSCOREA-ALATA L BY PARTICLE BOMBARDMENT

A biolistic particle gun was used to deliver genetic material into int act yam cells. Cultured suspension cells of D. alata were bombarded wi th microprojectiles coated with pBI221.2 DNA and histochemical assays were carried out to show transient GUS expression in bombarded cells. Stably transformed D. alata cells were recovered from cultured cells a fter bombardment with microprojectiles coated with pRT99gus harbouring both the nptII and uidA genes. Bombarded cells were selected on a med ium containing geneticin (G418). Two months after bombardment, calli r esistant to G418 were assayed for GUS expression. There was a 100% cor relation between resistance to G418 and GUS expression. From these cal li, four cell lines were established and GUS activity in each line was determined fluorometrically. The use of a specific GUS inhibitor show ed that the GUS activity was due to the introduced uidA gene rather th an to any intrinsic GUS-like activity originating from the plant. Inco rporation of the introduced DNA into the plant genomic DNA was confirm ed by Southern analysis.