Inside a program: how Graingene operates
GroundCover™ Issue: 46
LIFE WOULD get a lot easier for crop breeders if they had a genetic 'road map' allowing premium quality to be built into plant populations with certainty.
This offers major advantages since the competitiveness of Australian wheat is dependent on being able to meet or exceed customer expectations of quality - at the level of both the grain processor and consumer.
The Graingene project in the Quality program, led by Matthew Morell, is working on identifying the genetic factors underpinning important quality traits - with a view to improving selection efficiency.
"Specifically, this project is looking for markers for the genes required to produce wheats with superior product quality for specific applications such as sponge and dough breads and yellow alkaline noodles," said Dr Morrell.
Sponge and dough bread is a category of bread production in key Southeast Asian markets that is not successfully addressed by current Australian varieties. It requires a high-protein hard wheat with a combination of dough characteristics, such as strength and extensibility, in order to produce a high-quality bread after fermentation. Yellow alkaline noodles represent a premium market for APR or AR wheat and require the production of a firm noodle with excellent colour stability.
Do we have the quality trait or not?
"The project will examine the relationships between various grain, flour and end-product traits, and test methods for measuring these traits. At the end of the day the breeder, researcher or end user should be able to select the cheapest and most convenient testing method and have a high degree of certainty that the test is measuring a specific quality trait."
Other outcomes of the project include markers to accelerate breeding of wheats with specific quality attributes, and germplasm that meets and exceeds end-use specifications. Such wheats are expected to more regularly achieve target quality, and thus return premiums to growers.
Fast-tracking - genomics and molecular markers provide the edge
All living things contain genes. Scientists have traditionally studied one gene at a time to find its role in growth, development or other plant processes. There are around 30,000 to 40,000 different genes in a plant, so studying them one at a time is slow work.
Genomics is the study of all of the genes of an organism at the same time. Molecular markers are like flags in the genome that are easily detectable and are used to assist in the selection process of plant breeding.
They can be developed from information generated by genomics and can significantly speed up plant breeding, Graingene is using these new technologies to fast-track its research,
How the technology works to build water-use efficient varieties
"There is compelling evidence that wheat yields in Australia would be improved if we develop plant varieties that use available water more efficiently," said Richard Richards, leader of the Abiotic Stress program.
Water-use efficiency has complex inheritance and there are several projects within Graingene working on the structure of less thirsty wheat plants.
"Important traits that influence water-use efficiency include the ability for plants to reduce water loss during carbon uptake (i.e. greater transpiration efficiency), increased early vigour and better crop establishment," Dr Richards said.
The variable expression of these traits under different conditions makes them difficult to incorporate in a breeding program in a cost-effective way, So Graingene is developing molecular markers linked to these important traits and efficient ways to screen them, The process has been sped up considerably.
"The high through-put marker facilities in Graingene combine fully automated robotics with a strategic screening approach - using hundreds of markers positioned across the whole genome," Dr Richards said,
"This achieves the same results within weeks that previously required at least a year of fairly routine laboratory work.
"Applying this technology in Graingene will speed up the marker identification - in particular, for traits that show complex inheritance (controlled by several genes with small effect), Perhaps more importantly, it will free up human resources (hands and brains) to do the clever science needed for producing new, water-use efficient wheats for Australia,"
Graingene hopes by the end of the year to release Rees, its second variety incorporating the high transpiration efficiency trait to sit alongside Drysdale (released in 2002 and marketed by AWB Seeds).
DNA library on tap
Graingene now has another fast-track biotechnology tool with the contribution by Syngenta of over 36,000 pieces of sequenced wheat DNA.
Each piece represents a unique gene and can be used on a microarray. Microarrays or 'DNA chips' are high-density arrays of DNA attached to specially treated microscope slides.
The DNA is spotted onto the slides using precision robotics.
'High through-put' microarrays allow you to compare the genes switched on or off under particular conditions - for example, the genes that are active in wheat grown under drought conditions compared to wheat grown under normal conditions," said Liz Dennis, Technology Program Leader.
"It means you can analyse tens of thousands of genes simultaneously and possibly identify genes for the response to drought."
Combining the micro array technology with the high through-put marker technology, outlined above, can greatly speed up the identification of markers for traits with complex inheritance.
In this way, the Technology Program in Graingene is used as a tool by all the other programs to look for new genes of interest. Graingene aims for this type of integration across the entire research and commercial structure of its programs.