DAVIS, Calif. Researcher Jorge Dubcovsky and his team have identified one of the genes in wheat that increases yield the holy grail for farmers.
Yield the amount of wheat grown per acre is how wheat farmers pay the bills.
We always joke in wheat breeding that the first three top priorities are yield, yield and yield, Dubcovsky, a University of California-Davis wheat breeder, told the Capital Press. There are premiums and discounts for protein, but the grower is paid by the yield. Thats the only thing that the grower gets.
The gene Dubcovsky and his team discovered controls the maximum number of grains the plant produces. They estimate the discovery could eventually increase yields by as much as 5%.
Breeders devote most of their efforts to pursuing yield, Dubcovsky said.
You only advance varieties that will yield better than the previous one, Dubcovsky said. If not, nobody will buy it.
But, he said, yield has been a very difficult trait to crack.
The reason is many variables impact wheat yields.
One year, the varieties that dont shatter in the wind will yield more. The next year, there could be a disease. Another year, too much heat.
Its difficult to pinpoint whether a varietys overall performance is due to genes or other factors, Dubcovsky said.
Dubcovsky leads the research for WheatCAP, a consortium of 41 breeders and researchers at 22 institutions in 20 states.
Researchers have identified most of the genes that contribute to a good bread, including protein, loaf volume and uniformity, and use molecular markers to select for those traits.
Has he finally cracked the trait?
I think we have cracked the easier part of this difficult problem, he said with a chuckle.
How it works
In the future, farmers holding a new variety of wheat in their hands wont see any difference from todays wheat, Dubcovsky said.
But if you look at the end of the spike, you have one more spikelet at the end, he said.
The plants genes determine when to stop producing those spikelets, which hold the grain, he explained. Researchers want to enable the plant to produce spikelets a little bit longer.
The newly discovered gene, designated WAPO1, controls the maximum number of grains in a wheat spike. Breeding it into plants could make room for more grains to grow in each spike by delaying formation of the terminal spikelet.
The only thing you will notice is that a spike will be a little bit longer and have more of those spikelets on the side, he said.
Step by step
At its core, yield is measured by the number of wheat spikes per square foot of land, multiplied by the number of grains each spike has, multiplied by the weight of each grain, Dubcovsky said.
One of those components, the number of grains, is a little bit easier to do genetics with, he said.
Researchers have identified several genes that control the weight of grains, he said.
But a plant with more grains has to produce enough starch to fill them, or else farmers will end up with more but smaller grains, and a plant producing the same yield.
Now, researchers are working on the more difficult part of the question, Dubcovsky said: making a more robust plant, with more biomass, that can mobilize more starch to the extra grains to increase yield.
We have made a step forward, he said. We have half of the equation solved.
The gene already existed in half of the modern wheat varieties in the world, he said. Identifying it may benefit those varieties that didnt already have it. WAPO1 is frequently found in wheat varieties used to make bread flour but not in pasta wheats such as durum.
We know now in which varieties its present and which its not present, he said. We didnt know that before. We were blind.
But it will be years before higher-yielding wheat varieties appear in farmers fields. New varieties take 5 to 10 years to develop, Dubcovsky said.
The reality in breeding is that we go step by step, he said. In plants that have a good biomass, you can push yield 5%.
That might not sound like much of an improvement at first.
But given that the worlds wheat farmers raise 750 million metric tons each year, and wheat produces 20% of calories and protein consumed by the human population, and the need to soon feed 3 billion more people on the same amount of land, that 5% starts taking a different perspective, he said.
Two farmers
Gary Bailey and Andy Juris raise wheat about 200 miles apart in Washington state. For both farmers, yield is a major consideration when deciding which varieties to plant.
Their farms receive different amounts of rain.
Bailey farms in St. John and represents Whitman County farmers on the Washington Grain Commission board. His land can receive 14 to 17 inches of rain per year a lot for this part of the state.
For him, a typical winter wheat yield is about 80 bushels per acre.
Juris farms in Bickleton and is vice president of the Washington Association of Wheat Growers. His farm normally receives 8 to 10 inches of rain each year although last year during the drought it got 3 inches.
In a fallow rotation, in which he rests his soil some years, his average yield is 35 to 40 bushels per acre.
Where he does annual cropping in shallow soils that cant hold precipitation, he averages 25 bushels per acre.
Dubcovskys 5% increase would mean a bushel or two more per acre, Juris said.
Were kind of clinging on sometimes by our fingernails to the margins of what is considered decent, farmable ground, he said. Were always looking for that next percentage.
Time will tell
Breeders in the Pacific Northwest say Dubcovskys discovery will put another tool in their toolbox.
Identifying the gene wont directly affect general breeding efforts in the near future, but could help breeding for specific production systems long term, Washington State University spring wheat breeder Mike Pumphrey said.
If the genes already present in Oregon State Universitys germplasm, molecular markers can be used for marker-assisted selection, said OSU breeder Bob Zemetra.
If not, it could be bred into elite germplasm and evaluated to determine the impact on yield, he said.
Everyone agrees on one point: Quality must not be sacrificed.
Yield pays the bills, but if a grower is discounted for low quality, that can change how much theyre paid in a hurry, said Mary Palmer Sullivan, vice president of the Washington Grain Commission.
Pumphrey recommends growers watch reliable, replicated, multi-year, multi-location regional yield performance data, while considering other traits of importance.
As part of the WheatCAP consortiums $15 million grant from the USDA National Institute of Food and Agriculture, researchers are evaluating the effect of the genes in combination with other traits for increased yield, said Arron Carter, winter wheat breeder at WSU.
Researchers need to take a holistic approach with all components of production, Carter said, adding that top yield is dictated by genetics, climate, inputs, cropping system and soil health.
I dont think we have reached our limits yet, he said. I think genetics can continue to push yield higher.
GMO quandary
Years ago, corn and soybean yields skyrocketed with the advent of genetically modified organisms, or GMOs, in which genetic traits such as pest resistance are inserted into the varieties.
The global wheat market, however, has not embraced the technology. As yet, there are no commercialized varieties of wheat available in the market developed through biotechnology.
It is unfortunate that we cannot use GMOs in wheat, because we can do a lot more, Dubcovsky said. Basically, you are asking us to give you more food in the same space, and you tied our hands at our backs. But since those are the rules, we continue to do breeding with our hands tied at our backs.
Breeding will continue to improve without GMOs, he said. But GMOs would allow solutions to a lot of problems, including nutrition and the economic value of wheat.
I understand, people always fear what they dont know, and we need to respect peoples fear, he said. From a scientific point of view, theres no rationale on the limitations they are putting upon me (with) GMO. But I respect the people if people do not want to eat them, I will not produce it.
Investing in food
Dubcovsky, 65, said its also time to find a younger researcher to overlap with him at UC-Davis to eventually take up the mantel.
In the meantime, I will continue doing it, I enjoy doing it, he said.
Even when a new person arrives, hed happily keep helping out.
This is my passion, so I will proudly continue working on it, he said.
Sullivan, of the grain commission, notes that Dubcovsky identified the gene through federal research funding.
While each state that has a checkoff for wheat contributes towards research, we cant do it alone, she said. These are the types of grants and opportunities that we wouldnt otherwise have. The more information, and the more tools they have in their toolbox, the better off were going to be. Its a really good investment in taxpayer dollars.
Dubcovsky echoed the need to support agricultural research.
Food is not something thats sold in the supermarket, he said. Food is something you need to fight for and you need to invest for, if you want to have food on the table tomorrow. Producing food takes work of a lot of people.
Dubcovsky left research on yield for the end of his career because he knew it would be difficult.
Making a more productive plant requires a plant that grows faster, a little taller, with a stronger stem to support more grain.
It can be done, he said, pointing to triticale, a cross between durum wheat and rye, which has some of those traits.
We know that its possible, he said. Now we just need to figure out how to get there.
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The 5% solution: Researchers crack wheat's genetic code, open door to higher yields - Herald and News