We have led the way in the development of what has been hailed as a major breakthrough in molecular biology: silencing gene expression by RNA interference (RNAi). CSIRO's RNAi gene silencing technology is enabling researchers around the world to protect plants and animals from diseases, and to develop new plant varieties with beneficial attributes.

What is RNAi gene silencing?

Genes are found in living organisms and are passed on from one generation to the next. They are the coded instructions an organism uses to make proteins, and it is these proteins that make up the structures and perform the functions of living things.

Gene silencing is a way of reducing, or switching off, the activity, or expression, of single genes. As RNA is the courier that delivers the gene's instructions to make a protein, by changing the instructions for the RNA strand, a gene can be prevented from making its protein - therefore 'silencing' the gene.

Because of its effect on RNA, gene silencing is also referred to as RNA interference (RNAi). RNA interference is a naturally occurring mechanism that has evolved in plants and animals over millions of years as a defence against viruses.

In the 1990s, CSIRO's research led to the discovery of this naturally occurring gene silencing mechanism in plants. Their discovery led to a greater understanding of how the mechanism operates, in both plants and animals.

A photo of oil and safflower seeds being poured out of a laboratory beaker, the oil was produced with CSIRO RNA interference (RNAi) gene silencing technology.

RNAi gene silencing technology has enabled scientists to develop a safflower seed oil that contains more than 90 per cent oleic acid, a valuable fatty acid for industrial applications.

RNA interference (RNAi) is one of the most powerful technologies for discovering important trait genes and developing novel traits in plants and animals. CSIRO's RNAi technology adapts this naturally occurring process to provide a targeted and specific method of altering gene activity.

It holds tremendous promise as a therapeutic agent to control disease and prevent infection in plant and animal cells and has been adopted by research and biotechnology laboratories around the world.

In 2005, the RNAi team won a CSIRO Medal - an award which honours our biggest and brightest achievements for the year in the fields of research, business, and lifetime achievement.

Peter Waterhouse and Ming-Bo Wang also received the 2007 Prime Minister’s Prize for Science for their discovery of how to silence genes in plants.

Advantages of RNAi

There are many advantages for this proven technology over other methods used for reduction of gene expression . The RNAi technology is:

  • Precise: CSIRO's RNAi technology can target individual genes, even among a family of closely related genes. This means that only the gene of interest is affected
  • Fast: thousands of genes can be rapidly targeted using RNAi with today's high-tech laboratory equipment
  • Stable: traits based on RNAi have been shown to be stable for at least five generations
  • Flexible: RNAi is effective for different species and phenotypes
  • Controllable: researchers can turn off a gene completely or just 'turn down' its effects

RNAi technology can be used to identify which genes are responsible for particular traits so that breeders can produce non-genetically modified plants.

Examples of CSIRO's research with RNAi technology:

Breeding better wheat

Australia's grain industry produces around 25 million tonnes of wheat and generates more than US$6 billion annually. CSIRO has a long history of developing wheat varieties with beneficial traits for yield, quality and disease resistance and environmental tolerance. CSIRO's patented RNAi technology has been used through all stages of trait selection and development. This has included identifying genes of interest and validating them as potential targets, as well as observing phenotypes in proof of concept tests.

Increasing aquaculture productivity

Aquaculture is the world's fastest growing food production sector. CSIRO researchers are working with the aquaculture industry to achieve sustainable feed formulations, enhanced growth, survival and feed conversion rates and increased tolerance to viral diseases. RNAi technology is being used across CSIRO's aquaculture research to contribute to the following outcomes:

  • identifying genes associated with economically important traits
  • optimising the response to selection
  • reducing stock losses due to diseases, for example developing an experimental anti-viral that prevents prawn mortality from Gill-Associated virus.

Plants that are resistant to viruses

Viruses are a significant problem in many of Australia's crop plants, so having virus-resistant plants can mean many benefits to farmers, the environment and the economy. An example is where researchers developed cereal varieties with resistance to Barley Yellow Dwarf Virus. The virus can cause yield losses of about 15-25 per cent in cereals such as wheat and barley. Crops containing the RNAi against the virus are completely immune, whereas as the wild type plants are severely stunted by the virus infection.

Healthier cottonseed oil

Cottonseed oil is used extensively as an ingredient in margarines and cooking oils, particularly in the food service sector. When cottonseed oil is processed cholesterol raising trans-fatty acids are created. CSIRO has used RNAi to simultaneously reduce the function of three genes in cottonseed that normally convert oleic acid to polyunsaturated fatty acids or other undesirable fatty acids. The resultant high-oleic cottonseed oil is suitable for cooking applications and does not contain the cholesterol raising trans-fatty acids, making it a healthier oil for human consumption.

Better biofuels

CSIRO has produced safflower seed oil that contains more than 90 per cent oleic acid, a valuable fatty acid for industrial chemical production and fuel. RNAi technology enabled scientists to switch off the enzymes that convert oleic acid into the polyunsaturated fatty acids during seed oil synthesis.

What our licensees are doing with RNAi technology

Licensees of the technology are developing innovations to address plant, animal and human problems. Some examples include:

  • developing rice that is resistant to Rice Stripe Virus in China
  • producing new varieties of corn with increased resistance to Western Corn Rootworm
  • improving antibodies used to treat human diseases like Non-Hodgkin's Lymphoma and inflammatory conditions such as arthritis
  • finding ways to silence the Hepatitis virus's ability to reproduce itself.

Access to CSIRO's RNAi plant gene silencing vectors

If you are an educational or research organisation you can access CSIRO's plant gene silencing vectors to use within your organisation for research purposes. CSIRO plant vectors.

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