Light 'trick' to speed delivery of new crop varieties

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Photo of Dr Lee Hickey with wheat under continuous light conditions
Dr Lee Hickey among speed-bred wheat grown under continuous light.

A new high-protein milling wheat variety is being released in 2018 that includes genes that make the grain much more resistant to pre-harvest sprouting.

While the new variety, called DS Faraday, is a particular boon for northern growers who are frequently affected by summer thunderstorms, the technique used during its 10-year development is an important breakthrough for plant breeders worldwide.

Two pre-breeders at the University of Queensland, Dr Mark Dieters and Dr Lee Hickey, applied an innovative technique called ‘speed breeding’ to develop DS Faraday in partnership with Dow AgroSciences wheat breeder Nick Willey.

Dr Hickey explains that speed breeding gives researchers up to six generations in just one year for grains such as wheat and barley.

It was developed using an idea first floated by NASA to feed astronauts in space – the use of continuous light.

“Leaving the lights on in the glasshouse for 22 hours a day tricks the plants into the reproductive phase much more quickly than normal,” Dr Hickey says. “We started experimenting with continuous light over the next decade; the technique was refined by optimising the wavelength and intensity of light, as well as nutrients and temperature.”

On 1 January, all the protocols needed to use speed breeding were published online by one of the world’s most prestigious peer-reviewed journals – Nature Plants – in the article ‘Speed breeding is a powerful tool to accelerate crop research and breeding’. The protocols were produced in collaboration with the University of Sydney and the John Innes Centre in the UK.

interest around the world. Just seven days after its appearance, for example, it was tweeted 675 times and picked up by 43 news outlets. This is a virtually unheard-of response to a plant science paper and the buzz reflects the breadth of impact possible using speed breeding.

For breeders, the method allows for concurrent trait discovery and selection work. By cycling through six generations in one year, the technique greatly accelerates the deployment of new traits into commercial varieties, resulting in faster gains in crop productivity or resilience. This was the case with the grain dormancy traits used to develop DS Faraday.

Dr Hickey explains: “In the beginning we sourced germplasm that combined grain dormancy sources from Chinese and South African landraces. Normally breeders avoid such material as it takes too many crosses to move the desired trait back into elite cultivars and to weed-out undesirable DNA. Without speed breeding, it would not have been feasible to develop a new variety – we would still be working on it.”

This accelerated movement of traits now means it is universally easier to tap into the novel, unexploited traits conserved in gene banks.

The method can also be used to rapidly combine or ‘stack’ disease resistance and grain quality traits into elite germplasm – as is underway in Dr Hickey’s laboratories in partnership with LongReach Plant Breeders.

It provides an alternative to double haploids, as it is equally efficient at locking in the unique genetic profile of newly developed cultivars, while avoiding the need for specialised laboratories or the expense associated with double haploids.

For researchers, speed breeding also accommodates other advanced biotechnologies, such as gene editing, marker-assisted selection and genomic selection. It can be used to accelerate the creation of mapping populations needed to understand the genetic basis of new and useful traits. Such work is already underway in several projects in which the GRDC is investing.

There are even exciting opportunities to enhance crop productivity in terms of indoor and vertical farming systems.

To see the difference in growth rates possible with speed breeding, download the timelapse video at the 'Nature Plants' website. Recordings were made using the CropQuant workstation developed by Ji Zhou and colleagues at the John Innes Centre in the UK.