The National Botanical Research Institute (NBRI),Lucknow,is working to develop transgenic varieties of mangoes and bananas that will take longer than usual to ripen. The aim is to increase the shelf life of these fruits and,thus,cut down on their wastage during transportation. India produces 45 million tonnes of fruits every year but 30 to 50 per cent is lost to post-harvest deterioration. NBRI is researching how to delay fruit ripening and,in the process,produce transgenic varieties of mangoes and bananas with a longer shelf life, said Dr Aniruddha Sane,one of the four scientists engaged in the research work. Though such genetic modification has been tried in other parts of the world,this is the first such experiment in India, he added. Every one per cent reduction of loss will save the country around Rs 250 crore annually. The delay in fruit ripening will also boost exports,making Indian mangoes and bananas reach other parts of the world. Explaining the process of fruit ripening in climacteric fruits,Sane said the triggering factor for ripening is a plant hormone called ethylene. After the fruit grows fully,there is a sudden burst of respiration and the release of ethylene,which causes quick ripening and abscission (shedding) of the fruit. Due to auto-catalytic production,when the hormone is produced in any one fruit,it also triggers the production of the hormone in all other fruits. Thus,during transportation,when a banana begins to ripen due to ethylene,it also instigates ripening of other bananas in that truck,which leads to excessive softening and rupturing of many fruits and invites fungus and bacteria. Given the countrys geographical vastness,fruits ripen while being transported from north to south. Even if we manage to delay the process of fruit ripening by two days,it will save 30 per cent of the wastage. In tomatoes,we have managed to delay ripening by 8 to 10 days, said Dr Sane. The genes for ethylene biosynthesis in the DNA get activated during ripening to produce RNA which in turn forms the protein (enzymes) that produces ethylene in large amounts. By genetic engineering,the scientists at NBRI are aiming to reduce the effective RNA available to produce ethylene. Once this modification is achieved,the genes are transferred into plants through special bacteria which have the ability to infect plants and introduce part of their DNA into plants. Under controlled lab environment,these bacteria are modified so that they introduce the modified plant DNA back into the plants. The bacteria are then killed by growth on antibiotics so as to prevent the plant from further harm. NBRI has been successful with a similar experiment on tomatoes,which are being grown in the glass house of the institute. It is now collaborating with Bhabha Atomic Research Centre (BARC) for bananas due to availability of expertise for banana transformation there. It is waiting for the tissue culture to be completed in BARC before transgenic banana saplings can also see the glass houses of NBRI,where they are intended to grow into transgenic plants. Before the technique is utilized on field,at least three to four generations of the plants need to be watched in the glass house atmosphere to check the effect of genetic modification. Up to three generations of tomatoes have successfully been grown in NBRI.
