The secrets of wheat4 min read . Updated: 02 Jul 2011, 05:03 PM IST
The secrets of wheat
The secrets of wheat
The future of humanity—6.87 billion of us by the time you read this—depends on a kind of grass.
Also read | Samar Halarnkar’s earlier columns
Wheat, one of mankind’s most important food crop, is a domesticated grass, though it is as far removed from its ancestors as we are from ours. Wheat was one of the first plants to be cultivated, around 8,000 BC, when the age of agriculture dawned and encouraged mankind to abandon a life of hunting and gathering and create its first nation cities. Wheat grows in one-sixth of the world’s fields and feeds nearly half the world’s population. Without wheat, you can’t make pasta, biscuits, beer, baguettes or chapattis. We need wheat, almost like we need water and air. Worryingly, like water and air, global warming and rising demand from prospering, urbanizing societies are pushing the world towards a wheat crisis.
Last year, wheat prices saw their steepest rise in 50 years, as fire and drought destroyed one-fifth of the crop in Russia, one of the world’s important producers. China, the world’s largest producer and consumer of wheat, faced one of its driest winters in 200 years, though rain, snow and a gigantic irrigation effort over the last two weeks appear to have saved crops. Uncertain weather in Canada, Ukraine, Australia, Pakistan and several other wheat-growing countries threatens wheat supplies at a time when the world needs more food. India, the world’s second largest wheat producer, has happier news: record yields are likely when the harvest begins this month, but global output will struggle to match demand.
The stage is set for a big scientific intervention. Living as we are in the age of genetic manipulation, it should be possible to fiddle with wheat’s genes to produce new varieties that can tolerate drought, disease and yield more grain. The gene maps of rice and maize, the other two major global food crops, have already been decoded.
But the wheat genome—the gene maps, or biological information required to build life, encoded in DNA and divided into genes—hides its secrets well, and that has held back the development of new strains of wheat. Humans have about 23,000 genes; wheat has more than 80,000. The 17 billion base pairs, or letters of genetic code, in wheat’s helical wilderness are five times as many as the human genome. Science once believed it was impossible to decode the wheat gene map. Only in the last two years have computing and DNA sequencing technology advanced enough for scientists to finally take a crack at the double-helix of wheat.
When scientists in the UK released the first rough draft of the wheat genome six months ago—the human genome was decoded 11 years ago—it was the largest and most complex genetic decoding ever attempted. Wheat was the last of the major food crops to yield its genetic secrets. The genetic code of rice was unscrambled in 2005 (leading to drought-resistant and vitamin-enriched strains), corn in 2009 and soybeans in 2010.
The technique used to map the wheat genome was difficult, even by the arcane standards of genetics. The DNA was extracted, suspended in a fluid, then broken apart with bursts of gas. Chemicals and a high-resolution camera were used to discern its genetic make-up. This was made more complex because the UK team worked with Chinese spring wheat, a descendant of three species of wild grass. It is not a commercial variety but a laboratory strain, much like a lab rat.
It will be some years before full use can be made of the wheat gene map now posted on the Internet. Many more strains must be analysed for the work to be truly useful. It is important to provide some perspective to this research, as the International Wheat Genome Sequence Consortium, an umbrella organization of some 200 breeders, scientists and growers in 16 countries (including India), tried to do soon after the UK advance was announced. It said that the raw data produced “could be viewed as similar to having an unordered string of all the letters from a set of encylopaedia volumes". Their message: This is a step forward, but beware of media hype. Unlike normal scientific practice, the wheat advance was not published in a scientific journal. In its defence, the research team said it wanted the data “out there", so further study isn’t delayed.
Indeed, not everyone wants to be so cautious. “Whatever be (sic) the opinions made by claimants worldwide, this is an impressive first achievement and major breakthrough… several people around the world are going to be benefited directly or indirectly," says a paper in the latest issue of the Indian journal Current Science.
There are potential downsides to this breakthrough. If in five to 10 years new strains of wheat reach our tables and global food supply expands, will this not be further incentive for populations to grow? It might. That is quite another question.
Samar Halarnkar is editor-at-large, Hindustan Times. This is a fortnightly column that explores the cutting edge of science and technology. Comments are welcome firstname.lastname@example.org