BioWorld International Correspondent

MELBOURNE, Australia - A number of companies have tried and failed to devise ways of preventing hay fever and allergic asthma by halting the immune cascade initiated when sufferers breathe in pollen. Further products are in development currently.

Now Australian plant scientists have applied lateral thinking to the problem and come up with a way of stopping hay fever at the source - by rendering pollen non-allergenic. They have achieved that by knocking out the genes for two proteins, Lolp-1 and Lolp-2, which are the main culprits in rye grass pollen. Pollen from the modified plants fails to initiate an immune response in the sera of hay fever sufferers in vitro.

The plant has just been tested in field-scale trials in the U.S. and shown to be equivalent to its non-modified counterparts in all other respects. "We feel that the two allergens we have switched off are the cause of 90 percent of allergic reactions to rye grass," said German Spangenberg, research director for plant genetics and genomics at the Victorian AgriBiosciences Center (VABC).

VABC has established a joint venture called Gramina with PGG Wrightson, of Auckland, New Zealand, the largest grass seed producer in the southern hemisphere, to commercialize the non-allergenic rye grass.

Australia grows 60 million hectares of rye grass forage per year. The allergic rhinitis caused by its pollen affects about 20 percent of the population and is believed to affect a similar proportion of people in temperate climates elsewhere. There are about 1.8 million hay fever sufferers in Australia alone.

VABC opened in October to apply high-throughput genomics and computational biology to crop plants. John Brumby, treasurer and minister for innovation for the State of Victoria, said that it is seen as a key to future prosperity in Australia, where agricultural commodities are the second-largest export.

"Low allergy rye grass will have a global impact. Anywhere with a temperate climate where rye grass is a source of hay fever, there is the possibility of a cure," Brumby said.

"This shows we are up there with leaders in the world of agribiotech. We have identified the genes and taken them out of rye grass. The beauty of this discovery is that it is good for human health and good for agriculture."

However, the VABC researchers are not stopping there. They plan to stack two further traits into the rye grass before it is commercialized in 2013. One involves knocking out a gene that is involved in lignin formation, increasing the energy value by making rye grass easier for animals to digest, without affecting its structural strength.

They intend also to add a gene that occurs in some species of rye grass that increases production of the carbohydrate fructans, thus increasing its energy content.

Spangenberg said offering rye grass that links productivity improvements to such an enormous health benefit would make genetically modified crop plants more acceptable to the general public. A key element of the increased acceptability is that unlike first-generation GM crops, the second-generation products are not transgenics.

"This shows how the power of genomics to identify relevant genes is being applied to improve crop plants," Spangenberg said. Having generated plants that exhibit individual traits, the researchers use conventional breeding to bring the three together in one plant. The technique in effect turbo-charges traditional breeding, by allowing the targeted preselection of the trait of interest.

The methods are being applied also to Australia's other major forage crop, clover (alfalfa). There, researchers are working to develop a strain that is resistant to alfalfa mosaic virus, a major pest; is aluminum tolerant, allowing it to thrive in acidic soils; and produces tannins in its leaves, preventing the clover from causing bloat in the rumen of herbivores.

As well as increasing outputs of methane, a greenhouse gas, bloat has a major economic impact, causing estimated losses of A$100 million (US$76.4 million) annually.

All three traits are related to the activity of endogenous genes that occur naturally in clover. While the eventual aim is to produce a plant that exhibits all three properties, a version that is resistant to alfalfa mosaic virus is due to be commercialized in 2009.

Both projects draw on an earlier Australian program to sequence the genomes of rye grass and clover. That created a proprietary database containing 50,000 gene sequences from each plant. "I don't think anyone else has done such a comprehensive job," Spangenberg said.