Tomatoes that keep longer
N. GOPAL RAJ
— Photo: K.K. Mustafah
Less contentious: No new gene had being introduced into the transgenic tomato plants.
A team of scientists at the National Institute of Plant Genome Research in New Delhi has developed a technique to create transgenic tomatoes that do not become squishy even one and a half months after being plucked.
The same method may well be able to extend the shelf life of other fruit too, including banana, mango and papaya.
The technique, which has been patented, could help reduce the country’s post-harvest losses that run to thousands of crores each year, observed Asis Datta.
He is one of the corresponding authors of a paper with details of the research that is being published this week in the journal Proceedings of the National Academy of Sciences of the United States of America.
India is the world’s second largest producer of fruits and vegetables, but 35 per cent to 40 per cent of such produce is lost because of softening that accompanies ripening. The softening increases the damage during handling and transportation.
No new gene had being introduced into the plants, he emphasised. Instead, a method known as RNA interference was used to silence genes for two key enzymes.
The two enzymes, á-mannosidase and â-D-N-acetylhexosaminidase, were present at high levels during the ripening of many fruits, noted the scientists.
Genetically engineered tomatoes in which production of either of the two enzymes was blocked retained their texture and firmness for up to 45 days while the ordinary variety started shrivelling after 15 days.
The secret
The team found that suppressing these enzymes slowed the degradation of compounds that make up the cell wall.
The transgenic tomatoes, however, showed normal ripening and colour development while attached to the plant.
Several transgenic lines of tomato had been created using this technique, Prof. Datta told this correspondent. These lines could go into field trials after appropriate clearances were secured.
What about if both enzymes were suppressed in the same plant? “Let us see if we do both what happens,” he responded. “That is for the future.”
The high levels of the two enzymes in fruits such as banana, mango and papaya suggested their potential involvement in the softening process, the paper noted
It should be possible to extend the technique to such fruits too, he believed.
But even though the genes for the two enzymes would be largely similar to the ones in tomato, it would still be necessary to first clone those genes.
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