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Hot, sweet and strong

Biologist Ramesh Kumar Aggarwal has barely “walked” one-hundredth of the coffee genome, which is several hundred thousand DNA sequences long. But the scientist from the Hyderabad-based Centre for Cellular and Molecular Biology (CCMB) is already excited about the advances his team is making in understanding the genetic underpinnings of this much loved tropical bean.

Scientists from different laboratories in India have come together to explore the possibility of making coffee deliver more, both in quality and quantity. They made a small beginning when they mapped a part of the coffee genome as part of their larger goal to ferret out genetic links to desirable traits such as cup quality and the plant’s ability to fight pests, diseases and the vagaries of weather. The effort is being sponsored mainly by the Government of India’s Department of Biotechnology.

Aggarwal and his team reported in the latest issue of Theoretical Applications in Genetics journal that they have so far mapped 2,500 DNA sequences. Known as expressed sequence tags (ESTs), these represent portions of expressed genes that encode for proteins. These genetic markers come not just from coffee varieties that are commercially grown but other related varieties too. “Our next job is to link individual ESTs to biological traits, besides discovering more such DNA sequences,” says Aggarwal.

Besides the CCMB group, scientists from the Central Coffee Research Institute, the Central Food Technological Research Institute, Mysore, University of Agricultural Sciences, Bangalore, and Madurai Kamaraj University, Tamil Nadu, are also participating in the programme.

“The idea is to develop molecular and genetic tools to improve the Indian coffee plant through non-conventional means,” Aggarwal told KnowHow. The conventional breeding techniques that confer desirable traits on a crop plant through crossing varieties with highly variable characteristics have failed to work wonders. This is because each generation of coffee plant takes five-six years to flower, and it usually requires up to five generations to evaluate and release a new variety. It would thus need nearly 30 years to grow a new variety.

On the other hand, advances in molecular biology and genetics make it possible to significantly reduce the time required to bring forth a new variety. “An improved variety can be developed in just six-seven years, if we go by non-conventional breeding techniques,” says Jayarama, director of research, Coffee Board. Such techniques can also include a transgenic approach, for which the scientists require approvals from the Indian genetic engineering regulator, GEAC. “When transgenic food crops are allowed, we won’t lose much time in developing a transgenic coffee variety,” explains Jayarama.

Though there are over 100 kinds of coffee, only two species are grown commercially, Arabica and Robusta. While Arabica is known for better cup quality, it is extremely vulnerable to pest attacks and droughts. Robusta, on the contrary, withstands such conditions better, but is of inferior quality. India exports nearly 70 per cent of its coffee produce, making the tropical bean a significant foreign exchange earner.

The genetic improvements will help tackle two major diseases that afflict the coffee plant — white stem borer and coffee leaf rust. “If unattended, these diseases can reduce up to 70 per cent of the yield,” says Jayarama. Similarly, researchers at the University of Agricultural Sciences, Bangalore, are working on identifying genes that bestow tolerance to drought in other coffee-related species so that they can be transferred to Arabica plants to make them endure long spells of drought.

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