Wednesday, February 9, 2011

Wheat Genetic Gain Leveling Off

Wheat has been an important part of American history for years. It is a key food in the diets of many and is a very flexible and reliable food source. Recent study has found that wheat is no longer genetically diversifying like it used to. The genetic adjustments that had increased wheat yield in the past, has nearly come to a standstill. Farmers are now having issues trying to figure out how to more effectively breed and produce wheat to feed our ever - growing population.

With nearly 68 million metric tons of wheat harvested every year in the U.S., it is vital to find a new way to increase and expand this amount. The article mentioned that there are two possibile ways to do this. The first way is to change farming practices. Farmers would have to increase harvested produce. The second way is to breed wheat in a way that it becomes mature at desired times and fights against fungal infections.

With geneticist research, it has been discovered that genetic gain has been slowing since the 1980s, and has now halted. What is the reason behind all of this? Pathogens are a main contributor to the standstill. They are evolving more rapidly than breeders can keep up with and are getting out of control. Outside of the research, another geneticist had blamed genetic bottlenecks for the plateau in genetic gain. To increase yield, "dwarfing" genes were breed so that the plants could use more energy to produce grain. This is good in the short run because it gives more produce at a faster rate. In the long run though, non-dwarf varieties have been discarded and pushed aside which has greatly restricted the gene pool. A similar bottleneck has also been observed when choosing varieties that are resistant to particular pathogens. This ignores other varieties that are not so resistant.

So why not directly alter the DNA of wheat to program it to grow effectively and increase crop yields? It's not that easy. The wheat genome is very complex and the people do not like the sound nor are they open to genetically modified foods. Although the halt in wheat improvement is declining and is a concern, it is not yet a major issue. Until GMOs are more acceptable, better producing practices are the key to making more wheat.



  1. This is very interesting. It seems that the presence of pathogens would create strands of the wheat that are resistant. Farmers or seed distributors could use wheat that has survived attacks from harmful infections and distribute those to farmers. It must be more complex than that if the scientists haven't figured that out yet!

  2. The wheat genome was recently sequenced, which is a first step to understanding the potential for genetic engineering. One difficulty is that it is a hexaploid, made up of basically three diploid genomes in the nucleus. Thus, most genes are present in triplicate, which make modification a bit more challenging. The loss of genetic variability is a major issue with this and many crops as many landraces are being lost as only the "improved" varieties are grown. Although genes can be engineered, it is not easy to predict how they will behave in a plant, as opposed to being able to breed in a gene that is already present and has been subject to natural selection.