Genes from the plant that control its yield of the antimalarial drug artemisinin have been identified by scientists.

Artemisinin is extracted from the plant, Artemisia annua. When used in combination with other antimalarial drugs it is recognised as the most effective treatment for malaria.

Demand for the drug is likely to increase dramatically as new programmes such as the Affordable Medicines Facility make it cheaper for patients to buy malaria treatments.

Researchers from the Centre for Novel Agricultural Products at the UK-based University of York have now identified genetic markers for 'fast-track breeding' that will help produce higher-yielding A. annua plants.

Rather than sequence the whole genome of the plant, the team focused on parts of the genetic code called the transcriptome. "We chose to focus on the transcriptome as it represents genes that are expressed and doing something in the cell," co-author Dianna Bowles told SciDev.Net.

"By focusing on these, we got an idea of the genes that may well be the most functionally relevant to artemisinin yield, such as those involved in the manufacture of artemisinin and the size and architecture of the plant," she said.

The scientists constructed a genetic map to help them find genes that correspond to relevant traits in the plants.

"The results will enable people in the community [for example, those who farm the plants or manufacture the seeds] to use our data in their own breeding programmes," she added, "to generate better varieties tailored for the different growing regions in each of the developing countries".

Jacques Pilloy, of artemisinin combination therapies portal Artepal, estimates that the demand for the drug will increase from 100 tonnes now to 130 tonnes in 2013 — equivalent to 260 million treatments.

But only about 1.2 per cent of the plant can be converted into artemisinin, says Pilloy, so a large area of crop must be planted to obtain a small amount of the drug.

As well as increasing the amount of artemisinin available, the research will help farmers in developing countries who grow the crop, says Ian Bathurst of the Medicines for Malaria Venture (MMV).

"If farmers can either grow more plants per hectare, or the plants they grow are higher-yielding, they should be able to reduce their price and still make a greater profit," he said.

But the continued development of other methods for producing artemisinin — for example, from yeast culture or synthetic means (see New malaria drug technologies unveiled) — is vital, said Bathurst.

"In the next 3–5 years, other alternatives may become available," he added. "This will smooth out the supply chain, so in the event of a natural disaster there will be alternative supplies of artemisinin."

Source: SciDev.Net
Date: 15 January, 2010