Method for down-regulating gene expression in fungi

Abstract

The present invention concerns methods for controlling fungus infestation via dsRNA mediated gene silencing, whereby the intact fungus cell(s) are contacted with a double-stranded RNA from outside the fungal cell(s) and whereby the double-stranded RNA is taken up by the intact fungal cell(s). In one particular embodiment, the methods of the invention are used to alleviate plants from fungus pests. Alternatively, the methods are used for treating and / or preventing fungal infestation on a substrate or a subject in need of such treatment and / or prevention. Suitable fungal target genes and fragments thereof, dsRNA constructs, recombinant constructs and compositions are disclosed.

Description

RELATED APPLICATIONS [0001] This application is a continuation-in-part of PCT / IB2005 / 003495, filed Oct. 4, 2005, which claims the benefit under 35 U.S.C. §119(e) of U.S. provisional application 60 / 615,695, filed Oct. 4, 2004, the entire disclosures of which are incorporated herein by reference.FIELD OF THE INVENTION [0002] The invention relates to methods for controlling fungal growth on cells or organisms, methods for preventing fungal infestation of cells or organism and methods for down-regulating gene expression in fungi using double-stranded RNA. The invention also relates to transgenic plants resistant to fungal infestation. BACKGROUND TO THE INVENTION [0003] RNA interference or “RNAi” is a process of sequence-specific down-regulation of gene expression (also referred to as “gene silencing” or “RNA-mediated gene silencing”) initiated by double-stranded RNA (dsRNA) that is complementary in sequence to a region of the target gene to be down-regulated (Fire, A. Trends Genet. Vol....

AI Technical Summary

Benefits of technology

[0015] It has surprisingly been found that when intact fungal cells are contacted with double-stranded RNA outside the cell wall, the double-stranded RNA is taken up by the fungal cells in amounts sufficient to specifically cause inhibition of growth. This approach to RNAi in fungi avoids the need for complicated transformation procedures in order to introduce a transgene capable of directing expression of double-stranded RNA within cells of the fungus. Accordingly, there is no need for the fungus itself to be genetically manipulated and in particular no need to transform the fungal cells using non-natural procedures in order to introduce a DNA construct directing expression of dsRNA within the fungal cells. Hence, the technique is simple and of great practical utility and opens up a whole range of different applications of RNAi in fungi that simply would not be practical using the prior art techniques.

[0204] According to a still further embodiment, the present invention extends to a method for increasing plant yield comprising introducing in a plant any of the nucleotide sequences or recombinant DNA constructs as herein described in an expressible format. Plants encompassed by this method are as described earlier. Preferably, said plant is rice.

Problems solved by technology

However, to date RNAi has only been achieved in fungi by transcription of dsRNA within cells of the fungus, following transformation of fungal cells with a DNA construct or transgene from which the appropriate dsRNA may be transcribed.

RNAi techniques requiring transformation of fungal cells with a DNA construct that directs production of dsRNA within the fungal cells are useful for experimental studies within the laboratory but are clearly not suitable for many potential practical applications of RNAi, for example applications which require dsRNA to be introduced into many fungal cells on a large scale or in the field, for example, to protect plants against plant pathogenic fungi or large scale treatment of substrates to protect against fungal infestation, or for pharmaceutical or veterinary use in the treatment or prevention of fungal infestation in humans or animals.

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