India researchers squeeze more life out of tomatoes

Such advances are important for developing countries which rely heavily on agricultural exports for income but where logistical infrastructure like refrigeration is often patchy.

"We lose a lot of harvest all over the world. In India ... we grow tomatoes which cannot last more than 10 to 15 days. But if you can enhance (them), you don't need any storage system and you can transfer from place to place," lead researcher Asis Datta at the National Institute of Plant Genome Research in New Delhi told Reuters by telephone.

In a paper in the Proceedings of the National Academy of Science journal, the scientists said they analysed the genes of the tomato and identified those which appeared to be linked to two enzymes -- alpha-Man and beta-Hex -- that accumulate in the tomato during the time it is ripening.

They proceeded to "silence" these genes and found that those in which the alpha-Man enzyme was suppressed were 2.5 times firmer than conventional tomatoes, while those lacking in beta-Hex were two times firmer.

Both types of transgenic tomatoes retained their texture and firmness for up to 45 days, compared with conventional tomatoes, which started shrinking and losing texture after 15 days.

"When you go and buy tomatoes from a supermarket, you put it in a refrigerator and they can last for a few days, but not 10 to 15 days. But (with these transgenic tomatoes) you can keep them outside for 45 days, no problem," Datta said.

"We can use (this method) for mangoes, bananas, plenty of fruits."