Forum for Science, Industry and Business

Less Can Be More, for Plant Breeders Too

Imagine you are a rice breeder and one day within a large field you discover a plant that has just the characteristics you have been looking for. You happily take your special plant to the laboratory where you find out that the spontaneous, beneficial event was due to inactivation of a single gene.

This is a great observation; however, there are many different strains grown in different parts of the world, well adapted to the particular region they grow in. How can you now transfer the inactivated gene to other strains of rice?

Conventionally, you would have to go through years and years of breeding, until you have successfully transferred that single gene, without affecting all the other genes that are responsible for the target strains being so well adapted to their local environment. Would it not be great, if one could do this faster?

Using inactivated genes for rice breeding might sound far-fetched, but is not unusual. For example, the main change enabling the green revolution in rice resulted from loss of a gene that normally makes rice grow tall (and hence prone to toppling over if a plant makes many heavy rice grains). Thus, transferring inactivated genes is something rice breeders are indeed very much interested in.

Researchers at the Max Planck Institute (MPI) for Developmental Biology in Tübingen, Germany in collaboration with the International Rice Research Institute in the Philippines, have now generated a tool that should greatly speed up this particular aspect of rice breeding: According to a study published in PLoS ONE this week, a team led by Norman Warthmann (MPI) successfully demonstrated highly specific gene silencing using so-called artificial miRNAs in rice (Oryza sativa).

MicroRNAs are 20-22 bp long RNA molecules. In animals as well as in plants they have important functions in regulating gene activity. In plants, they cause highly specific degradation of sequence-matched messenger RNAs, which encode enzymes, regulatory factors or other proteins. The end effect is that the corresponding gene is silenced. With artificial miRNAs (amiRNAs), this natural silencing pathway can be harnessed to inactivate genes of interest to the breeder, with unprecedented specificity.

Detlef Weigel’s research group at the Max Planck Institute in Tübingen had initially pioneered this technique in the model plant Arabidopsis thaliana. The plethora of potential applications in agriculture now motivated them to try the method in rice. One of the rice genes they targeted is called Eui1. When Eui1 is inactive, the uppermost part of the rice plant and parts of the flowers grow taller and the plants can more easily fertilize neighboring plants, breeders use this genetic trick for hybrid seed production. Originally identified as a spontaneous mutant in a japonica rice variety, the eui1 mutation was introduced into indica varieties by several years of breeding. With an artificial miRNA targeting the Eui1 messenger RNA, the researchers at the International Rice Research Institute obtained within weeks plants with the desired property in two different rice varieties, including the agronomically important indica variety IR64, the most commonly grown strain in South-East Asia. Similarly, the researchers also report successful silencing of two other genes, Pds and SPl11.

Besides allowing the quick transfer of reduced gene function between different varieties, artificial miRNAs also accelerate the initial identification of important genes and the discovery of functions of genes that have not been studied before. Potential applications in rice breeding are manifold and they don’t stop at rice genes. By targeting pathogen-derived genes, for example, it should be possible to enhance virus and insect resistance. In addition, because they act dominantly, they are also perfectly suited for hybrid breeding.

MiRNAs have been found in all plant species examined so far. It should hence be possible to adapt the technique of gene silencing by artificial miRNAs to other crops and it may provide an important new avenue to enhance agronomic performance and nutritional value. Computer software to design the required oligonucleotide sequences and detailed protocols to produce amiRNAs are provided free of charge on the authors’ web site, at http://wmd2.weigelworld.org. Similarly, the artificial miRNA vector is provided free of charge to colleagues.

Rebecca Walton | alfa
Further information:
http://www.plosone.org/doi/pone.0001829
http://wmd2.weigelworld.org

Im Focus: Solving the mystery of quantum light in thin layers

A very special kind of light is emitted by tungsten diselenide layers. The reason for this has been unclear. Now an explanation has been found at TU Wien (Vienna)

It is an exotic phenomenon that nobody was able to explain for years: when energy is supplied to a thin layer of the material tungsten diselenide, it begins to...

Im Focus: An ultrafast glimpse of the photochemistry of the atmosphere

Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.

The nanocosmos is constantly in motion. All natural processes are ultimately determined by the interplay between radiation and matter. Light strikes particles...

Im Focus: Shaping nanoparticles for improved quantum information technology

Particles that are mere nanometers in size are at the forefront of scientific research today. They come in many different shapes: rods, spheres, cubes, vesicles, S-shaped worms and even donut-like rings. What makes them worthy of scientific study is that, being so tiny, they exhibit quantum mechanical properties not possible with larger objects.

Researchers at the Center for Nanoscale Materials (CNM), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE's Argonne National...

Im Focus: Novel Material for Shipbuilding

A new research project at the TH Mittelhessen focusses on the development of a novel light weight design concept for leisure boats and yachts. Professor Stephan Marzi from the THM Institute of Mechanics and Materials collaborates with Krake Catamarane, which is a shipyard located in Apolda, Thuringia.

The project is set up in an international cooperation with Professor Anders Biel from Karlstad University in Sweden and the Swedish company Lamera from...

Im Focus: Controlling superconducting regions within an exotic metal

Superconductivity has fascinated scientists for many years since it offers the potential to revolutionize current technologies. Materials only become superconductors - meaning that electrons can travel in them with no resistance - at very low temperatures. These days, this unique zero resistance superconductivity is commonly found in a number of technologies, such as magnetic resonance imaging (MRI).

Future technologies, however, will harness the total synchrony of electronic behavior in superconductors - a property called the phase. There is currently a...