Wheat & Barley Genome Projects
Since the beginnings of agriculture some
10,000 years ago, cereals have provided the main source of
calories for mankind. Recognised for their high yields,
nutritional value, and ease of transport and storage, a
range of different cereals were domesticated by the
world’s original farmers. Of these, wheat and barley
have been particularly important, providing the principle
grain stock that founded agriculture in the Middle-East and
led to its successful spread around the world.
Today, wheat and barley are grown throughout temperate,
Mediterranean-type and sub-tropical parts of both northern
and southern hemispheres. Globally, wheat and barley
contribute 25% and 8% of total cereal production,
respectively. In Australia, wheat and barley are by far the
most important crops, contributing approximately 70% and
25%, respectively, of total cereal production.
Over the millenia, human selection for wheat and barley
plants with superior yield and quality traits has led to
significant changes in cultivated varieties compared to
their wild relatives. For example, early selection by the
world’s first farmers led to the development of
varieties that produced grains of larger size that were
retained in the ear for longer. During the
20thCentury, the introduction of traits for
accelerated development, semi-dwarf habit and enhanced
disease resistance contributed to further, dramatic yield
improvements.
The Australian Centre for Plant Functional Genomics aims to
develop superior varieties of wheat and barley that have
increased tolerance to abiotic stresses, such as drought,
frost, waterlogging, nutrient deficiencies (such as
manganese, zinc and copper) and nutrient toxicities
(including salinity, sodicity, boron and aluminium). Since
most crops encounter one or more abiotic stresses at some
stage in their growth period, this will lead to significant
improvements in crop yield.
ACPFG Homepage
Goal/Deliverables:
The objectives of the Australian Centre for Plant
Functional Genomics are to:
• Identify the genetic mechanisms that control
tolerance to specific stresses and compare these with those
controlling broad range tolerance to abiotic stresses
• Use genome-wide analyses to define key cellular
processes that enable adapted plants to withstand abiotic
stress, and to apply that understanding of diversity for
the genetic improvement of crops such as wheat and barley
• Unravel regulatory networks that control plant
growth under abiotic stress
Identify ways of manipulating these networks, through
existing genetic diversity or through genetic engineering,
to deliver tangible industry outcomes, namely cereal
varieties better tailored to hostile environments.
ACPFG is involved in several international
programs to improve the genomics resources for wheat and
barley. Three key activities are
• the development of a physical map of the barley
genome, a collaborative program with the institute for
Leibnitz Institute of Plant Genetics and Crop Plant
Research, Gatersleben, Germany,
• the development of mutant and tagged populations
for barley to enhance functional analysis of candidate
genes
• the coordination of the International Triticeae
Mapping Initiative (ITMI).
ITMIwas established to provide support in
the coordination of research efforts in molecular
genetics, genomics and genetic analysis generally in the
Triticeae. The broad aims are:
1. to ensure data and information on the
Triticeae is readily available to all researchers,
2. to help avoid duplication of research efforts,
3. to provide a framework for accessing International
collaboration,
4. to help keep Triticeae research at the cutting edge of
genetic research.
In order to meet these objectives ITMI
provides up-to-date information on research programs,
provide a forum for discussion of ideas and for the
development of collaborative research programs. ITMI is
currently working with the international research community
to develop a broad vision of genome research in wheat
and barley.
Why sequence/study the genome?
Genomic research has been based on the study of a limited
number of model organisms that were chosen for their small
genome size and experimental tractability. However the
current thrusts of genome science are resulting in a new
vision where the study of diversity and organism complexity
is gaining prominence, often at the expense of model
organisms. Developments in crop genomics signal where the
significance of ‘models’ declines as
accessibility to genome technologies improves and the
social relevance of crop genomics to deliver ‘public
goods’ gains prominence.
Crop plants such as bread wheat were considered good models
for cytogenetic investigations and polyploidy research.
Wheat has one of the largest and most complex genomes of
any species. It is an allopolyploid containing three
different ancestral genomes (designated A, B and D) each of
which has seven pairs of homologous chromosomes (2n=6x=42).
The homologous chromosomes and genes in the different
ancestral genomes are referred to as
‘homoeologous’. Although these genomes are very
similar in gene content and order, chromosome pairing at
meiosis is restricted to homologous chromosomes. This
results in disomic inheritance which greatly simplifies the
pattern and interpretation of segregation data. The genome
size of wheat (17,000 Mb) which is approximately five times
the size of the human genome, was initially viewed as an
impediment to genomics research and most attention in
plants was focussed on the small genomes of model plants
such as rice and Arabidopsis. The initiation of
co-ordinated genomics initiatives with a global perspective
has dramatically changing our knowledge base and lead to
new opportunities for wheat genome research.
Two key features of the wheat (and barley) genome cannot be
addressed through studies of the simple model species;
polyploidy and the relationship between the large genome
size and chromosome behaviour, particularly with respect to
recombination. To some extent it is the interrelationship
between these features that makes wheat and barley
singularly fascinating organisms to study.
Recombinational behaviour and chromosome pairing in wheat
and barley is also showing some unusual features. It has
been known for some time that recombination in wheat
chromosomes is focused in the telomeric regions so that the
gene position along the chromosomes will affect the
exposure of that gene to recombination activity. Genes
subject to rapid change, such as many race-specific disease
resistance genes, are located in the recombinogenic
telometric regions while more highly conserved genes tend
to be positioned closer to the centromere). The large
genome size of wheat and barley may provide a mechanism for
developing and maintaining a strong recombination gradient
along the chromosomes.
These key questions will be central to future breeding
strategies for these species but they will be dependent
upon the development of physical maps and extensive
sequence databases for these species.
What is the benefit to Australia?
Wheat and barley are Australia’s
most important crops worth between $5 and $6 billion each
year to the Australian economy and occupying over 15
million ha (Australian Crop Report, 2003, ABARE). The
Australian cropping environment is harsh, with a range of
disease and environmental stresses limiting yield and grain
quality. Breeding still represents the most environmentally
and cost effective method for addressing limitations to
yield and enhancing grain quality and has a long and
successful history in Australia. However, the
competitiveness of the Australian cropping industries are
threatened through increasing pressure from other
producers, often heavily subsidised, pressure to reduce
chemical inputs and a deteriorating cropping environment,
for example the National Land and Water Audit (2002)
estimated that 3% to 6% of cropping land is now affected by
salinity, 5% by acidity, 50% by boron toxicity, 11% by
sodicity and most is affected by nutrient deficiencies. The
changing economic, political and natural environment means
that breeding programs will need to be increasingly
flexible and responsive. This will come through
improvements in the analysis and utilisation of genetic
resources and the rapid adoption of new technologies.
Information generated from existing wheat and barley genome
programs have clearly demonstrated that the characteristics
and behaviour of the genomes of simple model plant species,
such as Arabidposis and rice, provide few real insights
into the behaviour of large complex genomes. Therefore it
is important that we expand our understanding of the wheat
and barley genomes.
Analysis of the genome structure and sequence for wheat and
barley will provide information that will be critical to
the next generation of plant breeding strategies. The
information generated from this work and the links to
breeders keep Australian breeding programs at the leading
edge of breeding methodologies and places us in a strong
position to deliver well adapted varieties.
Download the detailed Business
Case
Contact Information:
Professor Peter Langridge
Chief Executive Officer
Australian Centre for Plant Functional Genomics
University of Adelaide
South Australia, 5064
AUSTRALIA
PHONE: (08) 8303 7368
FAX: (08) 83037102
EMAIL:peter.langridge@adelaide.edu.au
or peter.langridge@acpfg.com.au
URL: http://www.acpfg.com.au
