Four major Indian institutes have initiated work on producing tomatoes that bear vaccines against major infectious diseases. Starting with a vaccine for cholera, scientists hope to be able to produce a whole basketful of them, all accessed by just biting into a tomato.

Speaking at the Science Congress here yesterday, Dr Akilesh Tyagi of Delhi University said initial work on the vaccine-producing tomatoes has already begun, coordinated by the Department of Biotechnology (DBT). The vectors have been identified and the transformation process has fallen into place, Dr Tyagi said.

The process involves `injecting' the cholera gene into tomatoes and making the gene express itself in a desired way. The human body would then produce the antibodies, thus fighting thedisease.

In some western countries, the technique is being tried out with potatoes. However, in India, as research has shown that the potency of the vaccine may be reduced by boiling the vegetable, tomatoes have been selected as the carrier because they can be eaten raw. Another factor to consider here is that the stomach flora of Indians is so complex that edible vaccines get gobbled up even before they can get going. The research project has addressed this issue, and the vaccine will be tailor-made for Indian conditions, Dr Tyagi said.

``Such vegetable vaccines would be very useful because of the low production cost, easy transportation, large-scale production capabilities and the edible nature of the product,'' he said.

Indian agriculture scientists have also collaborated with Japanese and other global firms on getting the best genes to perform various tasks, including giving better yields and fighting pests. They have also been able to inject desired genes into rice plants, making them moreresistant to the vagaries of nature, Dr Tyagi said.

Earlier, in his presentation, Dr V L Chopra, former director of the Indian Institute of Agriculture Research, said India is also producing designer crops. ``You need not reap what you sow,'' he said, pointing out that with genetic manipulation, scientists can produce coconut oil with the properties of olive oil or full-flavoured coffee without caffeine. All that researchers have to do is to block certain genetic pathways and modify them to arrive at a desired product.

In his paper, Sir Richard Sykes, president of the British Association for Advancement of Science, gave a flavour of future medicine, when he said gene-specific drugs would make treatment more accurate with little or no side-effects. Identification of the APOE gene responsible for Alzheimer's Disease has opened up a new pathway. In just two years, the genetic book of life will be ready, giving full information on the possibilities of contracting diseases, their likely onset and a newmethod of gene repair. People would be carrying their information on a chip and computers would be able to give them a printout of their state of health, he said.

Dr Arie Altman of Israel outlined the efforts by agricultural scientists to weave the desired genes into plants to make them more tolerant to external stress and give more yield.