TRANSIENT GUS EXPRESSION IN ZYGOTIC EMBRYOS OF TAXUS-BREVIFOLIA

Germinated zygotic embryos of Pacific yew (Taxus brevifolia) were tran siently transformed with the expression vector pB1121, as demonstrated by expression of the beta-glucuronidase (GUS) gene. Embryos exhibited sectors of blue color following treatment with DNA and dimethyl sulfo xide (optimal concentration of 2.25%). However, transient expression d epended on the presence of ions in the buffer, as no GUS activity was observed when deionized water was used in place of other buffers. GUS gene expression was dependent on the developmental stage of the embryo , since the frequency of GUS expression was elevated in embryos incuba ted with the expression vector during a period from 4 to 8 wk after cu lture of DCR medium. In addition, the utility of using zygotic embryos from mature seeds for tissue culture and transient expression experim ents was also examined.