POLLEN VIABILITY AND TRANSGENE EXPRESSION FOLLOWING STORAGE IN HONEY

Transgenic plants of tobacco and Arabidopsis that produce genetically marked pollen, expressing the reporter gene uidA (gusA), were generate d to determine whether pollen proteins can be expressed and stable in honey, a potential route by which foreign proteins might enter the wid er environment. Hydrated tobacco pollen was found to lose viability ra pidly in honey, while pollen in the natural dehydrated form remained v iable for at least several days and in some cases several weeks, as de termined by FDA staining activity and germinability. Dehydrated pollen was found to be capable of transient foreign gene expression, followi ng microprojectile bombardment, after incubation in honey for at least 120 h. PCR amplification of transgene sequences in pollen of transgen ic plants revealed that pollen DNA can remain relatively intact after 7 weeks in honey. GUS enzyme activity analysis and SDS-PAGE of pollen proteins revealed that foreign and native pollen proteins are stable i n pollen incubated in honey for at least 6 weeks. We conclude that pol len may represent an ecologically important vector for transgenic prot ein products.