Antisense RNA Inhibition of β-Glucuronidase Gene Expression in Transgenic Tobacco can be Transiently Overcome Using a Heat-Inducible β-Glucuronidase Gene Construct

Abstract

A transgenic tobacco plant in which the constitutive expression of a single E. coli β-glucuronidase (GUS) gene had been completely repressed by antisense GUS RNA was crossed with another tobacco transformant containing several copies of the GUS gene driven by a 1.2 Kb D. melanogaster hsp70 promoter fragment. Southern blot analysis of the segregants in the F1 generation revealed different combinations of the sense, antisense and heat-inducible chimaeric GUS gene constructs. GUS activity in these segregants correlated with the presence and absence of the different GUS gene constructs. Transient heat induction of GUS activity was observed in some segregants in spite of the presence of the constitutive antisense GUS DNA construct. It was also possible to demonstrate the presence of sense GUS mRNA concomitant with the heat-inducible restoration of GUS activity in a plant where antisense GUS RNA had effectively suppressed GUS expression.