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`Full rice genome sequencing by 2005'

Our Bureau

NEW DELHI, Jan. 4

THE rice genome would be fully sequenced by the year 2005, according to Dr Gurdev S. Khush, Principal Plant Breeder and Head of the Plant Breeding, Genetics and Biochemistry Division of the Manila-based International Rice Research Institute (IRRI).

``When we started the work on gene sequencing two years ago, we expected it to be completed in 10-years time (by 2008). But now, this is likely to be finished by 2005'', Dr Khush said.

The sequencing work is being done under the auspices of the International Rice Genome Sequence Project (IRGSP), a consortium of research institutions from 10 countries, including India.

The other members include Japan, Canada, China, France, Korea, Taiwan, Thailand, the UK and the US. India is being represented by the Indian Council of Agricultural Research (ICAR) and the Department of Biotechnology (DBT).

Dr Khush said the advancing of the original schedule for completion of the project was partly facilitated by the US life sciences major, Monsanto, whose work in building had been claimed to be the first `working draft' of the rice genome. ``Monsanto had some data which it deciphered using the so-called shotgun approach and provided to IRSGP'', he added.

The rice genome has around 50,000 genes in 12 chromosomes. ``What the consortium has done is to allocate individual chromosomes to each country for sequencing. India, which was initially supposed to be sequencing chromosome number 8, is now working on ch romosome number 11'', he said.

ICAR and DBT have sponsored a Rs 60-crore project towards this purpose, with the sequencing being carried out at the National Research Centre on Plant Biotechnology here.

Dr Khush, however, noted that sequencing of the rice genome was just the beginning _ what breeders termed as `structural genomics'. This essentially entails knowing the exact order of the roughly half a billion chemical `letters' that make up the rice ge nome. But the real action would be in the realm of `functional genomics', i.e. understanding the precise role of each gene in the rice plant.

``Only once we know what each gene is contributing to the plant will we be able to move from structural to functional genomics'', Dr Khush said, while noting that as of now ``we know only about 200 genes at the most, all of which are not really useful''.

He said while the information on the entire rice genome sequence would be placed in the public domain, the functional genomics aspect pertaining to individual genes (once they are located) would, however, be amenable to patenting.

``Our efforts would be to see to it that publicly-funded institutions such as IRRI would be active even in the functional genomics arena, so that information pertaining to these are also available freely to the public'', he said.

Dr Khush, who is attending the 88th session of the Indian Science Congress here, has led IRRI's rice varietal improvement programme for the last 33 years. During this period, he has overseen the commercial release of 320-odd paddy varieties, which accoun t for roughly 50 per cent of the total planted rice area in the world. Of these, 35 lines have been released in India alone, including famous varieties such as IR-36 (sown in 11 million hectares worldwide during the 1980s), IR-64 (8-9 million hectares) a nd IR-72.

The 65-year-old Punjab-born plant breeder, who is considered by many to rice what the legendary Dr Norman Borlaug has been to wheat, said of the 600 million tonnes of paddy produced in the world, China accounted for 208 m.t., followed by India at 135 m.t .

While the average paddy yields in India, at three tonnes per hectare, was half that of China's six tonnes, ``our yields are almost the same when it comes to irrigated areas''. Unlike China, where the entire rice acreage was irrigated, the corresponding p roportion was only 50 per cent here.

He said out of 30 major food crops, 50 per cent of the world calorie supply was met by just three _ rice (23 per cent), wheat (17 per cent) and maize (10 per cent).