The Green Revolution, that near-mythical time nowadays where the imaginations of technology became real and millions of lives were saved from starvation, was, sad to say, never a full solution to the problem. It was a stop-gap. An incredibly successful one that managed to push back the looming issue for decades, but still only temporary nonetheless. It was inevitable that we’d have to deal with the same exact concerns again and it isn’t like agricultural science has stopped advancing since then.
In total, humanity has been doing its best to deal with issues of overpopulation, of famine, drought, and other conditions caused by the spread of climate change. Our new technologies nearly outnumber the ability to count them and they may truly, finally, be enough to fix the problem for good. But that doesn’t mean we can stop, we have to keep moving forward.
One of the things that appears to be stemming this continuation is the speed at which we can produce unique crops with new and desired traits. In short, it takes too long to make them, even with our far greater advanced speeds and tech available today. We have to find more and better.
A Need For Speed
NASA was one of the organizations that helped to try and tackle this over a decade ago where they began a series of studies into enhancing the breeding speed and efficiency of crops. This so-called speed breeding saw some improvements from their research, but it was slow going and never truly finished. Other scientists then took up that mantle.
Now, in a collaboration between Australian scientists at the University of Sydney and the University of Queensland and UK scientists from the John Innes Centre, the science of speed breeding has just leaped forward in both conception and reality. While there are most definitely benefits in direct yield from this process, their main focus was on being able to develop fast growing cultivars that could benefit genome editing and selection breeding for other traits, which could also end up being yield selected traits.
Most crop breeds manage only 1 or 2 harvests a year, with a select few going up to as many as 3. But in cross-breeding for traits, it usually takes 4-6 generations to obtain a line that is stable enough for use. As you can imagine and probably math out, that process takes a number of years to achieve. Any reduction in that requirement of invested time would be a huge boon to agricultural research all over the world.
An Overabundance of Light
The researchers decided to work with 6 different crop varieties that would be most benefited from this process: wheat, durum wheat, barley, chickpeas, common peas, and canola. An additional model organism, or model grass as it were, Brachypodium distachyon was used for control testing. They were all placed in a contained greenhouse-esque environment with climate controls and were exposed to 22 hours of light and 2 hours of darkness. Time without there being light rather than continuous 24/7 light was done in order to help stimulate circadian rhythms and the plant genes connected to them.
The time it took until the flowering period, known as anthesis, was estimated to be around half the time as compared to traditional greenhouse growth rates. For the model organism, it only took 26 days and it took 37 to 39 for the wheat. While the wheat were found to product less spikes than normal, the difference was not significant and both the wheat and barley in general produced a regular helping of spikes. They also ensured that the offspring from crosses of the wheat cultivars were still able to grow the same under speed breeding conditions themselves, indicating that there is no negative generational effects.
This first test had only involved the wheats, barley, and the model organism. They followed it up with another experiment using the full cohort of crops discussed before, this time outside a lab and in a temperature-controlled glasshouse with specialized high pressure sodium lamps for the 22 hours of light cycle. They also set up a control in a different glasshouse with a normalized 12 hours of light cycle, but with the same temperature setup.
Success In Many Forms
All of the crops saw a huge reduction in time until flowering, with wheat seeing 22 days, barley seeing 64 days, canola seeing 73 days, and the peas seeing 33 days. The amount of seeds, and wheat spikes, produced were the same as the average with the control. It was additionally found that the plants in general reached anthesis much more uniformly at the same time within a species, with all of a group having it occur nearly simultaneously. This was a far better result than with the controls and it is a very helpful trait for breeders that need two plants to be flowering in order to cross them.
Wheat seed that had been harvested early was found to still be viable after cold temperature treatment, indicating that complicated embryo rescue techniques aren’t needed when using speed breeding for early harvested seeds.
The single seed descent method, a common growing option used by agronomists where a single random seed from a plant is used to grow its progeny and the plants in general are grown at a high density in the greenhouse setting, was tested with speed breeding. Too high of a density was found to reduce growing speed somewhat, but the seeds collected two weeks after flowering were found to be 80% viable and those four weeks after flowering were 100% viable. This showed that single seed descent and speed breeding can be utilized together, along with early seed harvesting, in order to rapidly go through generations in a cultivar.
For Future Traits
It was announced afterward that they had managed to collectively increase the number of harvests through speed breeding to 4-5 per year on average for the crops. This would make it possible to make stable cultivar lines and genome editing testing and crossing of lines happen that much faster, reducing overall production times to less than 2 years, as compared to the 5 year average that things currently sit at.
The whole purpose of their study, as they put it, is to lower the barrier to entry of modified crops so that they can enter the world marketplace sooner. The ability to create stable cultivar lines is paramount to achieving that and this new speed breeding method may be just what is needed to jumpstart a new batch of crop lines out there by scientists everywhere and anywhere in the world.
Photo CCs: 103 2934 from Wikimedia Commons
