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Grow faster, grow stronger: speed-breeding crops to feed the future
[SYDNEY] Farmers and plant breeders are in a race against time. The world population is growing rapidly, requiring ever more food, but the amount of cultivable land is limited. Warmer temperatures have extended growth seasons in some areas — and brought drought and pests to others.
"We face a grand challenge in terms of feeding the world," said Lee Hickey, a plant geneticist at the University of Queensland in Australia. "If you look at the stats, we're going to have about 10 billion on the planet by 2050 and we're going to need 60 per cent to 80 per cent more food to feed everybody. It's an even greater challenge in the face of climate change and diseases that affect our crops that are also rapidly evolving."
But plant breeding is a slow process. Developing new kinds of crops — higher yield, more nutritious, drought- and disease-resistant — can take a decade or more using traditional breeding techniques. So plant breeders are working on quickening the pace.
Hickey's team has been working on "speed breeding," tightly controlling light and temperature to send plant growth into overdrive. This enables researchers to harvest seeds and start growing the next generation of crops sooner.
Their technique was inspired by NASA research into how to grow food on space stations. They trick the crops into flowering early by blasting blue and red LED lights for 22 hours a day and keeping temperatures between 62 and 72 degrees Fahrenheit. In November, in a paper in Nature, they showed that they can grow up to six generations of wheat, barley, chickpeas and canola in a year, whereas traditional methods would only yield one or two.
On Monday in Nature Biotechnology, Hickey and his team highlight the potential of speed breeding, as well as other techniques that may help improve food security. Combining speed breeding with other state-of-the-art technologies, such as gene editing, is the best way to create a pipeline of new crops, according to the researchers.
"What we're really talking about here is creating plant factories on a massive scale," Hickey said.
A new era in plant research has arrived, says Charlie Brummer, director of the Plant Breeding Center at the University of California, Davis, who was not involved in the work. Breeders and breeding companies have always tried to minimize the time it takes to develop a new variety of crops, but with new technologies like speed breeding, "we can do it better now than we could in the past," he said.
Botanists first started growing plants under artificial light — carbon arc lamps — 150 years ago. Since then, advances in LED technology have vastly improved the precision with which scientists can adjust and customize light settings to individual crop species.
Researchers have also adopted new genetic techniques to optimize flowering times and make plants more resistant to the rigors of a warming planet. Unlike older crossbreeding and crop modification techniques, newer tools like CRISPR allow scientists to snip out portions of the plant's own DNA that may make it vulnerable to disease. Hickey and his team are working on adding CRISPR machinery directly into barley and sorghum saplings, in order to modify the plants' genes while simultaneously speed breeding them.
This is easier said than done for some crops. Potatoes and some other crops, such as alfalfa, are tetraploids, carrying four copies of each chromosome. (Humans and most animals are diploid, with two chromosomes, one from each parent). A breeder might want to delete one gene that decreases crop yield, but there may be three more copies of the gene on the plant's other chromosomes.
This unique inheritance pattern means that potatoes are typically sterile, and must be propagated by harvesting them and replanting tubers. Speed breeding and genetic editing can only fast-track propagation to a certain extent, said Benjamin Stich, a plant geneticist at the Heinrich Heine University of Düsseldorf, Germany.
Stich and his team are developing a technique called genomic prediction to fast-track the identification of tubers with desirable traits. First, the researchers take what they know about how various genes influence growth and yield. Then, they input that data into computer models and extract predictions about which plants will have the best combination of genes and yield in the field.
"We can now predict many traits simultaneously, with high reliability," Stich said. His team has used the technique to successfully predict tubers' susceptibility to potato blight, as well as their starch content, yield and time to maturity.
With cheaper, more powerful technology, opportunities are opening up to improve crops around the world. Hickey's team plans to train plant breeders in India, Zimbabwe and Mali over the next couple years through a collaboration with the International Crops Research Institute for the Semi-Arid Tropics and grants from the Bill and Melinda Gates Foundation.
"It's important to make sure this benefits farmers in developing countries, too," Hickey said. Most speed breeding can be set up with minimum skill, and, in countries where electricity and other resources may be lacking, it can be done using solar panels to power cheap LEDs. Speed breeding can also be combined with gene editing and genomic prediction.
"One technology alone is not going to solve our problems," Hickey said. "We're going to need all the tools in the shed."