Gene mix and match to lift frost tolerance
GroundCover™ Supplement Issue: 109 | 03 Mar 2014 | Author: Janet Paterson
New research aims to determine the best gene combinations to lift the frost tolerance of Australian wheat varieties
Before flowering many winter wheats are tolerant of extremely low temperatures, down to minus 20°C in some cases. However, after head emergence wheat suffers severe damage at much milder temperatures (minus 4°C).
CSIRO scientist Dr Ben Trevaskis wants to identify gene combinations that enable wheat to maintain yield potential under frost – and he is prepared to search the entire Australian wheat genome to find them. “The aim is to identify combinations of genes and traits that help wheat to either avoid or tolerate frost or recover lost yield potential following frost damage.”
Dr Trevaskis has a valuable genetic resource available to help achieve the task – a special wheat population that is virtually identical genetically except for flowering behaviour.
“As the wheat plants differ only in flowering time and length we can get a really clear handle on how flowering traits interact with environmental conditions – including frost,” Dr Trevaskis says.
Dr Trevaskis will grow the wheat plants in trials across the GRDC cropping regions and identify the flowering characteristics that help wheat to avoid or tolerate frost.
“We will also be looking for plants that are able to compensate for frost damage by producing larger or additional grain in response to losing florets and grain to frost.”
Flowering-trait genes showing promise under frost will be captured via molecular marker technology and fed back to breeding companies for incorporation into new wheat varieties.
“We will also feed the best 10 lines into the Australian National Frost Program for detailed testing using their frost damage measurement system.
“We want to identify the optimum flowering-time genes for frost avoidance across Australia’s agro-ecological zones and also those combinations of genes that enable wheat plants to tolerate or compensate for frost events, such as those associated with spike length, tiller number and plant height.”
Dr Trevaskis says there is a treasure trove of mutations within cereal flowering-time genes that have faced natural selection over millions of years.
“There is strong evidence that the genes that control flowering in response to cold also influence frost tolerance, with frost tolerance declining as plants prepare to flower,” Dr Trevaskis says.
For example, wheat varieties bred for the cold areas of northern Europe and North America are extremely frost tolerant in winter, during vegetative growth, but lose this frost tolerance once they start to flower in spring.
“We want to find ways to maintain frost tolerance during flowering by examining how flowering behaviour interacts with the genetics of frost tolerance.”
Dr Trevaskis is also using the CSIRO four-way Multiparent Advanced Generation Inter-Cross (MAGIC) wheat population to investigate whether combinations of traits can improve yield stability in frost-prone regions.
“The MAGIC population randomly shuffles all the traits from four elite Australian wheats into a population of test lines,” Dr Trevaskis says.
Dr Trevaskis will measure the yield stability of the MAGIC lines across different sowing times at frost-prone sites in New South Wales and Western Australia.
“The hope is to identify trait combinations such as spike length, flowering time and tiller number that provide greater yield stability following frost events in each of the regions.”
The MAGIC population enables genes underlying specific traits or trait combinations to be linked to molecular markers, which can then be used to accelerate the development of new wheat varieties.
Any lines that perform well under frost will be put through rigorous testing at a third site in Toowoomba, Queensland, by research collaborators Dr Troy Frederiks and co-workers at the Queensland Alliance for Agriculture and Food Innovation.
“This third test site is an important part of the project because different regions have different types of frost and we want to be sure that any potential genetic solution for frost during flowering holds up across multiple environments,” Dr Trevaskis says.
The Toowoomba trials will use a special artificial light method to coordinate the flowering of different wheat varieties in the field.
“By synchronising flowering we can determine whether differences in frost tolerance are due to intrinsic genetic differences or because the plants are avoiding frost through flowering time.
“We can also determine how the different wheat lines compensate for yield lost to frost at flowering through changes in grain size or tiller number.”
More information:Dr Ben Trevaskis, CSIRO,
02 6246 5045,
GRDC Project Code CSP00180
Region National, North, South, West
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