Diving in the barley genepool
Barley is a hardy crop, producing reliable harvests in
areas with poor rainfall and soils. It is also versatile– a major food for millions of people, a key animal
feed, and the principal ingredient in beer and other beverages.
Studies of genetic diversity in barley are helping to unlock evolutionary secrets – and to better target varieties for
specific environments
ICARDA scientists have studied barley for more than
30 years, developing varieties better adapted to
diverse growing conditions and improved techniques
now used worldwide. In 2009, they continued
innovative work on the genetic diversity and evolution
of barley, also using biotechnology.
Assessing genetic diversity
The barley genepool is very diverse, containing tens of thousands of genotypes, many of which are represented in the ICARDA genebank's 25,000 barley
accessions.
Together with scientists from Morocco's National
Agricultural Research Institute and Southern Cross
University in Australia, ICARDA looked at genetic
diversity and geographical differentiation in 304
accessions from 29 countries. These included wild
barley as well as landraces – local or indigenous
varieties grown by farmers for generations.
The scientists found that the barley accessions fell
into three distinct germplasm pools: East Africa
(Eritrea, Ethiopia) and South America (Ecuador, Peru,
Chile) in one group, the Caucasus (Armenia and
Georgia) in another, and the rest in a third group.
This provided some interesting insights and raised
questions about the evolution of barley.
Exploring evolution
For example, in the case of East Africa and South
America, why should widely separated traditional
varieties be genetically similar? There are two
possible answers: either South American landraces
originated from East Africa, or the two groups shared
common parents at some stage of their evolution.
Landraces from North Africa (Egypt, Libya, Morocco,
Tunisia) in the third group were similar to East
African landraces. A possible explanation is that
because both regions grow barley for food, selection by
generations of farmers gradually led to convergence.
But there could be a simpler explanation– generations-old travel, migration, and trade between the two regions.
The most diverse regions in the study were North
Africa (especially Morocco), East Asia (the Tibet region
of China), and the Near East (the Fertile Crescent). This
suggests that barley may have been first domesticated
in one of these regions (the primary center),
transported by people to another (the secondary
center), and later, gradually spread to other parts of
the world. Alternatively, it could have been
domesticated independently in more than one place– possibly the Fertile Crescent and Tibet.
Another major study, conducted jointly by ICARDA,
CIMMYT, and universities in Australia and Mexico,
looked at genotype-by-environment interactions in
barley. The researchers analyzed 27 years of data from
750 trials in 75 countries to identify 'megaenvironments',
and within each 'mega-environment',
the best locations to breed new barley varieties.
Studies like these are providing new insights into crop
adaptation and helping to better target new varieties at
appropriate environments.
More detailed studies are needed, but one thing is
certain: with biotechnology tools becoming cheaper
and more accurate, scientists are making very rapid
progress in exploring the genetic diversity of barley.
