TOMATOES genetically modified to stay fresh for 30 days longer have been developed by scientists.
The team found a way to keep tomatoes firm for 45 days, when usually they would start to go soft after 15. They said the breakthrough could apply to other fruit – including bananas, mangoes and papaya.
The scientists identified the chemicals that make tomatoes go soft. By suppressing two enzymes, known as A-Man and B-Hex, which accumulate at critical stages during ripening, the researchers were able to extend shelf-life by a month.
They believe the finding could provide a boost for farmers who can lose almost half their harvest because of softening that makes their fruit shrivel up and go rotten before they can get it to the shops.
Dr Asis Datta and colleagues at the National Institute of Plant Genome Research in New Delhi used genetic engineering to "silence" the enzymes in tomatoes and showed those lacking A-Man were about two-and-a-half times firmer than conventional counterparts. Tomatoes without B-Hex were twice as hard.
Both types of genetically modified tomatoes retained their texture and firmness for up to 45 days compared with conventional ones which started shrinking and softening after only 15.
The researchers whose findings are published in Proceedings of the National Academy of Sciences said the GM plants grew normally and produced typical amounts of vegetation and fruit which matured at the usual rate.
Dr Datta said: "Overall the results demonstrate a substantial improvement in fruit shelf-life."
Previous efforts have been made to combat the problem by blocking proteins that damage fruit cells but these have met with "very limited success", he said.
He emphasised that there were no "ill effects". "In conclusion the engineering of plants provides a strategy for crop improvement that can be extended to other important fruit crops," he said.
India, the world's second largest producer of fruit and vegetables, loses about 40 per cent of produce due to softening.
The Scottish Government has a moratorium on planting GM crops in Scotland.
It argues this respects the consumers who demand locally-produced conventional and organic food.
In 2008, scientists developed purple tomatoes which they argued may be able to keep cancer at bay. They incorporated genes from the snapdragon flower, which is high in an antioxidant pigment called anthocyanin that is thought to have anti-cancer properties.
