Fine tuning wheat genomes would help regional wheat varieties feed a growing population by potentially doubling global production.
In a first-of-its-kind analysis of the untapped genetic potential of wheat undertaken by an international team of experts, it has shown that global yields are only half of what they could be.
The team, led by the UK’s Rothamsted Research, said this ‘genetic yield gap’ could be closed by developing wheat varieties tailored to each region by utilizing the vast genetic variation available in global and historical wheat gene banks with modern techniques, such as speed breeding and gene editing.
Dr Mikhail Semenov and Dr Nimai Senapati, who co-led the study, defined a crop’s ‘genetic yield potential’ as the highest yield achievable by an idealized variety – in other words, a plant with an optimal genome that allowed it to capture water, sunlight and nutrients more efficiently than any other.
Dr Semenov said: “Current wheat cultivars are, on average, only at the half-way point with respect to the yields they could produce given the mismatches between their genetics and local wheat growing conditions. Global wheat production could be doubled by the genetic improvement of local wheat cultivars, without increasing global wheat area.”
The researchers ran millions of computer simulations to design ‘perfect’ wheat plants that were tailored to local environments. When compared to the performance of locally adapted cultivars, in all cases they found current wheat varieties were underperforming for grain yield.
According to Dr Senapati, closing the genetic yield gap would go a long way to feeding the growing world population and would reduce pressure to convert wild habitats to farmland.
Wheat is the world’s most widely grown crop and in terms of human consumption, it is the second most important crop after rice, with global harvests in the region of 750m tonnes. Since the 1960s’ ‘Green Revolution’, yields have, on average, tripled – but this study suggested there is more to come.
It is the first time this type of analysis has been done globally with the study, published in Nature Food, looking at a total of 53 wheat growing regions across 33 countries and covering all global wheat growing environments.
Using a state-of-the-art wheat model, called Sirius, the team first calculated the potential yield from a total of 28 commonly used wheat varieties grown at these sites, assuming the best possible cultivation conditions for each one. This gave harvests of less than 4 tonnes in Australia and Kazakhstan – compared with 14 tonnes of wheat produced per ha in New Zealand.
Next, they ‘idealised’ local varieties within the model, optimizing several plant traits that contribute to yield and whose underlying genetics would allow them to be improved by plant breeders.
The results showed that by optimizing key traits, genetic yield gaps could be anywhere from 30-70% across different countries, with a global average genetic yield gap of 51%. Therefore, global wheat production could be doubled by exploiting this existing genetic yield gap towards achieving global food security in a sustainable way.
“Not unsurprisingly, the countries with the lowest current yields could gain the most from closing their genetic yield gaps,” said Dr Senapati. “That said, even improvements in those countries with a medium genetic yield gap of 40 to 50%, but with a large proportion of global wheat harvest area – such as the leading producers India, Russia, China, USA, Canada, and Pakistan – would have a substantial effect on global wheat production due to the larger wheat cultivation areas involved.”
Before this study, the size of these genetic yield gaps at country and global scales were unknown. The genetic yield gap idea contrasts with the longer-understood concept of traditional yield gap due to sub-optimal management where harvests are smaller than the best-case scenario as a result of factors such as pest or diseases, lack of nutrients, or sowing or harvesting at the wrong time.
“Our analysis suggests that such genetic yield gaps due to sub-optimal genetic adaptation could, in relative terms, be as large as the traditional yield gap due to imperfect crop and soil management,” said Dr Semenov.
Also involved in the study were leading wheat experts from Australia, Denmark, France, Germany, The Netherlands and Mexico.