CHIANG MAI: A research team at the National Center for Genetic Engineering and Biotechnology (BIOTEC) has developed a method of growing oranges that could prevent the spread of a disease that has ravaged crops in northern Thailand.

Citrus greening disease is transmitted by insects. It discolours, stunts the growth of fruit and makes it taste bitter.

But BIOTEC researchers have discovered a method of culturing disease-free plants in the laboratory, which they claim will increase the disease-resistance of orange plants and mitigate the worst effects of the disease.

They say the breakthrough could save the livelihoods of orange farmers, many of whom are facing financial hardship as a result of the disease.

BIOTEC researcher Tharathorn Teerakathiti said his team, which has been working on laboratory tests since 2011, has found a way to extract cells from fertile orange seeds and grow healthy test-tube plants.

It takes between six months and one year to sprout each new healthy offshoot. Disease-free trees can then be transferred to an indoor nursery for three months before being moved outside for six months and eventually planted on trial farms.

"We do need to wait and see whether the results are positive for the next three years after cultivation," she said. "But we are pinning our hopes on success. If it works, farmers will be able to limit massive losses caused by outbreaks."

Chiang Mai's Fang district produces the most oranges in the country, with 180,000 rai of plantations. But a severe outbreak of greening disease has hit around 30,000 rai of that farmland since 2010.

The owner of M K Orange Farm, Veerachai Chongsuwanwattana, estimates that more than 60% of orange farmers have been affected by the disease. He said he hoped the Biotec development would help put an end to the disease, which is the single biggest challenge facing citrus growers.

However, Likit Maneesinthu, an adviser to the BIOTEC project, cautioned that diseasefree orange trees in the lab do not necessarily guarantee plants will be immune from the disease in the outside world. Despite this he said the technique should lessen the effects of the outbreak and help a larger proportion of healthy trees.

Mr. Likit cited the success of a similar technique used to grow virus-free orchids by researchers in the US. That technique also reduced farmland orchid infections.

BIOTEC has also been working on a project to improve the taste of pickled cabbage. Vethachai Plengvidhya, chief of the microorganism study, said his team had successfully used Lactobacillus plantarum as a starter culture to ferment Chinese cabbage.

The work was carried out on behalf of the Peace Canning Company, one of the country's biggest producers of tinned pickled greens. The firm had been losing around 20% of profits on each batch of Chinese cabbage due to unstable methods of fermentation that caused it to sour too much.

Reference : APINYA WIPATAYOTIN.2014. Citrus greening disease tamed. Bangkok Post. (16 July 2014): 4.