How did barley, a plant native to the Middle East and South-Western Asia, become able to grown on land from just below the arctic circle to the equatorial highlands and southerly latitudes? The answer lies in the combined forces of evolution and natural selection, according to recent research published in the influential journal Nature Genetics.
In research that could have significant implications for the ability of breeders and farmers to respond to our changing climate and ensure food security, an international team of researchers from the Scotland, Germany and the USA have highlighted the potential benefits of understanding the huge natural diversity that is found in collections of locally adapted crop plants and their wild relatives.
Wild barley originates in a region called the Near East Fertile Crescent (present-day Egypt, Israel, Syria, Jordan, Iraq and Iran) where it germinates in the autumn, grows slowly over the cool winters and flowers early in the next summer. However, as barley grains were carried by ancient farmers and traders migrating west and north into more temperate climates, Its lifestyle had to adapt to the different environments that it encountered. Eventually, over a period of some 10,000 years, on the fringes of its range it became a crop that could be planted in the spring, avoiding the ravages of harsh northern winters and allowing rapid growth during the long cool days of summer, maturing in early autumn.
Using the latest genomic approaches, the research team sequenced the gene compliment of a collection of 267 landraces and wild species and identified a complex pattern of genetic variation associated with geographic and environmental variables. By growing the lines together in trials in the Scotland, Germany and the USA they were able to identify strong correlations between days to heading (flowering) and plant height with seasonal temperatures and summer rainfall at their original collection sites, suggesting these factors were major drivers of environmental adaptation.
The authors explain “Barley is really a hardy crop. It spread throughout the world because it adapts well to different environments. An adaptable crop is very important when you think about issues such as climate change and food security”.
Knowing which of barley’s 40,000 or so genes has been responsible for its environmental adaptation will ultimately help breeders select new varieties that can cope with emerging climate scenarios. It will allow selection of plants better able to grow in more marginal environments in both the developed and developing world, especially important as cropping areas are forced to expand to tackle the challenge of food security.
“Understanding the patterns genetic variation recorded in the genomes of crop plants that have become adapted to specific but diverse environments promises to reveal how the process of mutation and natural selection has allowed plants to become successful in their own specific environmental niche” says Prof. Robbie Waugh from the James Hutton Institute and University of Dundee. “Using this type of information should help us design crop varieties better able to cope with impending climate change”.
The group hope that follow-up research will ultimately allow breeders to be more predictive and sophisticated in the strategies they adopt to breed for a changing environment.
The paper “Adaptation of barley to different environments revealed in the exomes of a range-wide collection of landraces and wild relatives” is published in the most recent issue of the journal Nature Genetics.