Transformation of soybean via particle bombardment of embryogenic suspension culture tissue

Abstract

Embryogenic suspension culture tissue of soybean (Glycine max Merrill.) was bombarded with particles coated with plasmid DNAs encoding hygromycin resistance andβ-glucuronidase (GUS). One to two weeks after bombardment, embryogenic tissue was placed in a liquid proliferation medium containing hygromycin. Four to six weeks after bombardment, lobes of yellow-green, hygromycin-resistant tissue, which began as outgrowths on brown clumps of hygromycin-sensitive tissue, were isolated and cultured to give rise to clones of transgenic embryogenic material. In vivo GUS assays of hygromycin-resistant clones showed that the early outgrowths could be negative, sectored, or positive for GUS activity. Transgenic, fertile plants could be routinely produced from the proliferating transgenic embryogenic clones. Southern hybridization analyses confirmed stable transformation and indicated that both copy number and integration pattern of the introduced DNA varied among independently transformed clones. Hybridization analysis of DNA from progeny plants showed genetic linkage of multiple copies of introduced DNA. An average of three transgenic clones were obtained per bombardment making this procedure very suitable for transformation of soybean.