A new paper in Nature magazine summarizes a project to delineate the DNA code of bread wheat. The results add to the growing number of crops and other plants whose genomes have been decoded, which facilitates genetic comparisons for evolutionary studies, crop improvement through breeding, and other biological work.
Proteins in bread wheat have properties that make dough elastic. This allows it to trap gas bubbles from yeast, causing the bread to rise to form classic loaves not possible with other grains. Flickr photo by Dave Pullig
Bread wheat is particularly challenging to study due to the large size of the genome and because it contains a lot of repeated DNA sequences that are hard to line up in the right order. Bread wheat is actually derived from the hybridization of three different closely related grasses, so it contains many similar genes derived from each of the progenitors, making it difficult to sort out.
The DNA sequences carry a lot of fascinating information about the structure of the wheat genome that will keep biologists busy. But there are also many practical implications.
Diversity is the key
As with other crops, the genetic diversity of current commercial wheat varieties—the source of crop and food characteristics, from taste and texture to pest resistance and drought tolerance—is much lower than for wild relatives of wheat. Domestication resulted in a “genetic bottleneck” that reduced genetic diversity. Use of limited sources for wheat breeding has further restricted the genetic diversity of commercially grown wheat and other crops.
But the reduced genetic diversity of current crop varieties also presents an opportunity to greatly improve these crops and the food derived from them.
As noted by the authors:
The genomic resources that we have developed promise to accelerate [breeding] progress by facilitating the identification of useful variation in genes of wheat landraces and progenitor species, and by providing genomic landmarks to guide progeny selection. Analysis of complex polygenic traits such as yield and nutrient use efficiency will also be accelerated, contributing to sustainable increases in wheat crop production.
This conclusion reinforces other work, such as an earlier comparative genetic study of commercial wheat varieties, wheat wild relatives, and landraces—the local varieties that have been developed in place for centuries by small farmers.
Using this diversity for breeding—in conjunction with, and for the benefit of, small farmers in developing countries as well as larger farms in developed countries—and for adaptation to diverse agroecosystems (rather than unsustainable monocultures), will be crucial in coming years. Doing so will increase crop resilience in the face of climate change and improve food security and food sovereignty.
So it is troubling that this diversity could be threatened by the widespread introduction of engineered crops, without proper provisions to protect landraces from contamination or replacement.
That is why over 2,500 scientists and others have signed a petition protesting the proposed planting of engineered maize (corn) in Mexico, the place where corn originated and the region of its highest genetic diversity. It is also one of the reasons for similar concern about the introduction of engineered eggplant (brinjal) in India, the center for genetic diversity of that crop.
The relevance of breeding
The important message of the Nature paper could not be more different from the poorly informed pronouncement of the Wall Street Journal’s “Market Watch” that breeding can’t cut it:
“Indeed, by 2050 the world will need to double its food production to feed the population of what will then be an estimated 9 billion people. Sorry, traditional methods won’t hold. Both an increase in crop yields and areas are needed. And there are mitigating factors to both, climate change among them.”
By “traditional methods” Kostigen seems to mean everything but genetic engineering (GE). While GE may make some contributions, breeding, far from being outdated, and is vastly outpacing crop engineering for producing the very traits that Kostigen mentions.
If Kostigen represents the opinion of investors, it is all the more reason why the public sector needs to greatly increase investment in both conventional breeding and agroecology research.
Better to listen to knowledgeable commentators, such as Daryll Ray and Harwood Schaffer, respected agricultural economists from the University of Tennessee. Their recent blog post points out the opportunistic and self-serving “false dichotomy” set up by the big seed companies and their supporters. The companies claim that we either accept GE and chemical-centered agriculture as the solution to the challenges of food production in coming decades, or accept lower-yielding organic farming as the alternative, which would lead to the decimation of uncultivated ecosystems and possible hunger.
As Ray and Schaffer aptly put it:
“By positing organics as the only alternative to the full use of their products, they [big ag companies] hope to quash any challenge to their vision. They also ignore a lot of other actions that could be helpful in meeting the challenge of feeding 2 billion additional people by 2050—an increase of 28 percent over a 38-year period. In taking on this challenge, we need to remember that we were able to move from feeding a world population of 4 billion in 1974 to feeding 7 billion in 2012—an increase of 75 percent over a 38-year period.
From our vantage point, one needed action is to reduce post-harvest loss, which can be as much as a quarter to a third of the crop. To do this, low-input storage technologies need to be identified that use resources that are available to farm households and can be maintained over the long-haul by the poorest of the poor.”
They go on to point out that productive intercropping, the improvement of neglected crops from the global south like millets, cowpeas, sorghums, and others, and methods like sensible crop rotations developed at Iowa State and elsewhere, are the ticket.
Their prescription is similar to that of the IAASTD, an international effort enlisting several hundred scientists and others, and our recent report about drought tolerant crops. And they go on to remind us that: “The real challenge in feeding all 9 billion people in 2050 is not production; it is distribution.” For example, despite having more food-insecure people than any other country, India exports food.
Ray and Harwood conclude “The first step in meeting this challenge is to enable the farmers who are among the poorest of the poor to produce their own food using sustainable technologies that are within their resource base.”
I could not have put it better.