A chemically inducible gene expression system and its application to inducible gene suppression in rice

Abstract

The viability of the estrogen-receptor (ER)-based chemically inducible gene expression system LexA-VP16-ER (XVE) in combination with the site-specific DNA recombination Cre/loxP system in rice was examined using transgenic plants introduced with a plasmid vector pUH-GFP2 that controls the expression of a green fluorescent protein (GFP) gene. β-estradiol applied to the germinating seeds of the transgenic plants, successfully induced the mRNA expression of the GFP gene. Inducible gene suppression was also tested by replacing the GFP gene by an RNAi cassette; this cassette targeted OsSPS1, a gene encoding sucrose phosphate synthase. When the RNAi plants were treated with the inducer, the transcript levels of OsSPS1 decreased. Concomitantly, the plant length became shorter or the sucrose/starch molar ratio in the leaf blades decreased, suggesting the successful suppression of the target gene. Finally, the utility and remaining problems of this inducible expression system are discussed.