DNA clue to a better class of potato

PUBLISHED : Sunday, 28 August, 2011, 12:00am
UPDATED : Sunday, 28 August, 2011, 12:00am


Even small potatoes have their DNA sequenced now. And a company in the Netherlands has just announced the successful genetic sequencing of Cannabis sativa, the annual plant that has been widely consumed for centuries as an intoxicant and a medicine.

More commonly known as marijuana, or 'grass' in the American vernacular, the plant has been legalised in 16 US states for medicinal use over the last decade. The legal market for the substance is currently growing by 50 per cent every year.

Now, it should be possible to isolate the genes responsible for making the plant's pharmaceutically active compounds: THC, CBD, and some 60 other cannabinoids. Particular drug-producing genes could be isolated and concentrated in particular strains of the plant, or even inserted into other species.

We now know the full DNA sequence, or genome, of many bacterial, animal and plant species: they are as different as the panda bear, silk worm, rice, malaria mosquito, honey bee, dog, cat, fruit fly, zebra fish, chicken, mouse, rat, chimpanzee, and man. The humble potato and cannabis have now joined this elite group of species.

The potato belongs to the Solanaceae, or nightshade, family, which also includes tomato, capsicum, and aubergine.

The sequencing of its genome will help to speed up the development of new varieties, which in turn may help to ensure food security.

In the mid 19th century there was a famine in Ireland when the fungus Phytophtora exterminated almost all potatoes grown in a monoculture. Throughout the famine years, nearly a million Irish arrived in the United States. Famine immigrants were the first big wave of poor refugees to arrive in the US and Americans were simply overwhelmed.

Upon arrival in America, the Irish found the going to be quite tough. With no one to help them, they immediately settled into the lowest rung of society and waged a daily battle for survival.

One of the most extraordinary descendants of these immigrants was John Fitzgerald Kennedy, great-grandson of Patrick Kennedy, a farmer from County Wexford, in Ireland. One might say a fungus and potatoes helped make JFK the first Catholic to be US president.

The research findings on potato genome, published in a recent issue of the journal Nature, begin to unravel the secrets of the world's most important non-grain food crop. They may help to create crops with greater nutritional value and resistance to pests and diseases.

They will also speed up the time-consuming process of developing new varieties with improved yield, drought tolerance and disease resistance - which currently takes between 10 and 12 years, by which time we will have many more mouths to feed.

Potato consumption is ever expanding in developing countries, which now account for more than half of the global harvest.

In the Nature article the scientists write: 'If we're to feed the nine billion people projected to be living on the planet by 2050 then potato crops with improved water uptake and resistance to disease and drought will be an important development.'

Researcher Dr Gerard Bishop, from Imperial College London, said that the wider crop research community has been 'eagerly' awaiting the news.

'The potato genome will also help our understanding of closely related crops, such as tomato, which will be of enormous benefit.'

What about inserting the cannabis genes into potatoes? Hope nobody is coming to this idea!

Reinhard Renneberg is professor of bioanalytical chemistry at the Hong Kong University of Science and Technology