杏吧原创

The world could theoretically double the amount of wheat it produces by breeding versions of the crop that are genetically optimised for different regions. However, crop scientists not involved in the work are sceptical.

Crop experts have previously estimated the 鈥渕anagement gap鈥� 鈥� or the difference between existing yields of wheat and the theoretical potential yield that could be achieved with better management of irrigation, fertiliser and other factors. Now, for the first time, a team has calculated the size of the 鈥済enetic yield gap鈥� 鈥� the difference between yields today and the maximum yield if the plant鈥檚 genome was perfectly adapted to absorb nutrients, water and sunlight in different climates.

Australia and Kazakhstan had the highest genetic yield gap at 70 per cent, meaning they could benefit the most from an optimised wheat genome. New Zealand was lowest at 30 per cent. The global average, weighted against wheat harvest areas, was 51 per cent, suggesting the world could one day double wheat production simply by tweaking wheat genetics and without having to grow more of the crop.

鈥淚t鈥檚 a surprise that it鈥檚 that big. There鈥檚 been quite a long time for [genetic] optimisation, but it clearly hasn鈥檛 happened in many parts of the world. The finding is a reason for optimism because [optimising genomes] is one of the ways you can find the additional yield that we鈥檙e going to need in the next few decades,鈥� says at Rothamsted Research, UK, a member of the team who modelled the genetic yield gap.

The study comes as wheat prices have after Russia鈥檚 invasion of Ukraine disrupted grain supplies and hot weather affected key producer countries including India. Halford and his colleagues are clear that closing the genetic yield gap isn鈥檛 a short-term fix. But in the longer term it could help compensate for climate change, which is expected to curb yields of wheat because wheat plants experience heat stress above 34掳C.

鈥淚t鈥檚 a modelling study,鈥� says at Rothamsted, another member of the research team. 鈥淚t鈥檚 not a solution which could be implemented straightaway, and it鈥檚 a big, big challenge to achieve this. But theoretically, we鈥檙e sure that we can.鈥�

The team arrived at its estimates by looking at climatic data for 53 sites from 33 wheat-growing countries in conditions representative of how 91 per cent of the world鈥檚 wheat is grown. The gap between yields today and the maximum from an idealised genome for that location was estimated using a computer model known as Sirius. Semenov says the use of a single model is one limitation that future research could address.

Optimising the genome of wheat cultivars to increase yield could be done via traditional plant breeding or in a much faster way via gene-editing technology, which the UK has made easier to use by relaxing rules on growing experimental crops in trials. But even Halford鈥檚 team acknowledge that incorporating all the desirable genes into an idealised genome for one region would be challenging, and achieving the full 51 per cent increase 鈥渕ight not be readily possible at present鈥�.

Commercial wheat breeders in the UK employing cutting-edge technologies are only achieving around 1 per cent genetic yield gain each year, says at the University of Reading, UK, who wasn鈥檛 involved in the study. 鈥淭here is always some scope for the rate of gain to be increased by introducing technologies such as gene-editing that have not yet been widely-deployed but to suggest that there is a whole raft of unexploited and game-changing breeding technologies that would allow wheat yields to be doubled any time soon is fanciful,鈥� he says.

Meanwhile, better management of wheat production might yet prove a simpler way to produce more of the crop to feed the world. Reducing the yield management gap is currently much more feasible than the genetic yield gap estimated by the new paper, says at the University of Barcelona, Spain. He says the research is a good simulation exercise but adds: 鈥淚 don鈥檛 share their optimism of doubling yields just based on breeding.鈥�

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