Transgenic tomato ready for field trial

By Archita Bhatta
Published: Saturday 30 September 2006

-- (Credit: AVRDC)tomato production may receive a major boost if the field trials for a transgenic variety developed by a team of scientists at the Indian Agricultural Research Institute (iari) are successful. The new variety is resistant to the leaf curl disease, which cuts down tomato production by as much as 65 per cent.

Led by Anupam Varma, the scientists cloned a gene from the tomato leaf curl virus which when introduced into the plant countered the virus replicating gene, thus preventing the germ from multiplying. iari may soon collaborate with a private company to carry out field trials for the new variety.

Some scientists believe that this approach may be safer than the popular gm (genetically modified) technology method known after the bacteria, Bacillus thuringiensis (Bt).

"Whereas Bt technology involves the introduction of a gene from B thuringiensis in the concerned plant which generates toxic proteins that kill certain insect pests, the technology used in tomato involves introduction of a gene which prevents the proliferation of the virus causing the leaf curl disease," says Shelly Praveen, one of the researchers. She says the iari approach does not involve production of toxic proteins. It is based on cloning the structure of the gene from the virus in an antisense (or opposite) orientation, which then blocks the expression of the virus-replicating gene. The findings appeared in Plant Cell, Tissue and Organ Culture (Vol 83, No 3, December 2005).

"The efficacy of this procedure was established earlier. As the disease is widely prevalent in India, this approach is certainly worth trying," says biotechnologist P M Bhargava, who is vice chairman of the National Knowledge Commission. "However, the variety must go through a rigorous risk assessment procedure before field trials. I would emphasise that till now no genetically modified organism released anywhere, including Bt cotton in our country, has gone through an appropriate risk assessment procedure," he adds. Scientists have also stressed that this genetic manipulation should be used in local varieties and not in seedless hybrid varieties, which farmers have to buy afresh every year.

They say that the virus-resistant trait was observed up to the third generation of the plant in which it was introduced. "We have received the approval of the Review Committee on Genetic Manipulation for the technology and we will be going in for Genetic Engineering Approval Committee's tests after the field trials are done," adds Praveen.

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