Inverted repeat of a heterologous 3'-untranslated region for high-efficiency, high-throughput gene silencing

This report describes a method for the easy generation of inverted repeat constructs for the silencing of genes of unknown sequence which is applicable to high-throughput studies. This improved procedure for high-efficiency gene silencing is specific for a target gene, but does not require inverted repeat DNA of the target gene in the construct. The method employs an inverted repeat of the 3'-untranslated region (3'-UTR) of a heterologous gene, and has been demonstrated using the 3'-UTR region of the nopaline synthase (nos) gene from Agrobacterium tumefaciens, which is often used as the 3'-UTR for transgene constructs. In a population of independent tomato primary transformants harboring a stably integrated polygalacturonase (PG) transgene driven by a constitutive promoter and linked to an inverted repeat of the nos 3'-UTR, 51 of 56 primary transformants (91% of the population) showed highly effective post-transcriptional silencing of the PG gene, with PG mRNA abundance in ripe fruit reduced by 98% or more. The method was also effective in Arabidopsis, where two different, relatively uncharacterized plant transcription factors were also targeted effectively. This method has the advantage of ease and rapidity in preparation of the constructs, since a gene of interest can be inserted into a binary vector already containing the promoter and the inverted nos domain in a single-cloning step, and does not require any knowledge of the DNA sequence. The approach is suitable for high-throughput gene silencing studies, where it is necessary to investigate the function of hundreds to thousands of uncharacterized genes.