Pre-breeding for water use efficiency

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A comprehensive discovery, testing and delivery chain for water use efficiency traits has been created with GRDC investment to help improve yield resilience to various kinds of drought under Australian growing conditions

Efforts to improve the water use efficiency (WUE) of Australian wheat, barley and durum varieties has intensified in recent times using a combination of laboratory and finely controlled field-based research.

GRDC yield and quality traits manager Dr Jorge Mayer says improving WUE requires the ability to measure each trait accurately and determine its contribution to yield under moisture stress.

“The soil moisture profile over the growing season turns out to be the most important variable that needs to be controlled to reduce random effects and achieve target environment types representing realistic field conditions,” he says.

To enable this, the GRDC has established managed environment facilities (MEFs) – field trial sites where moisture levels can be controlled throughout the season using irrigation and rainout shelters.

Three MEFs are up and running in three contrasting regions of the Australian wheat belt: Narrabri in northern NSW, Yanco in southern NSW and Merredin in Western Australia. The facilities are run in collaboration with the University of Sydney, the NSW Department of Primary Industries (DPI) and the Department of Agriculture and Food, WA (DAFWA).

Pre-breeders are collaborating to lift the WUE of grain production systems. One sought-after outcome, says Dr Greg Rebetzke of CSIRO Plant Industry, is that germplasm assessment specifically targeting new WUE traits is now better able to highlight the trait’s value to commercial breeding programs.  

“This value is made more obvious when the performance of new traits can be compared with yields in commercial varieties and advanced breeding lines growing alongside each other,” he says. “In many cases, the delivery of new WUE traits to breeders is facilitated by their transfer into existing Australian varieties, the availability of improved selection tools, and breeder-friendly molecular markers.”

The MEF field sites go a long way to making such gains possible, Dr Mayer says. The GRDC has invested $10 million over five years (2010–15) in setting up the three sites and running eight concurrent WUE pre-breeding projects. These range from new traits such as ‘mesophyll conductance’ (near field-trial phase) through to validation of simplified screening technology for established WUE traits, such as the use of canopy temperature to track transpiration efficiency (TE). The eight projects are listed in Table 1 (page 19).

Feeding into the MEFs is technology to better monitor (or ‘phenotype’) plant performance developed at the Australian Plant Phenomics Facility, especially the Canberra node headed by Dr Bob Furbank (GRDC project CSP00148, 2011–14).

Crop Mobile Module in action; a man stands in the buggy in the foreground while the blimp is airborne in the background.

The ‘machine vision’ sensors built by the High Resolution Plant Phenomics Centre to study variation in plant physiology have been mounted onto tractors and blimps, allowing phenomics to roam paddocks where yearly millions of plots are sown in Australian field trials.

PHOTO: Carl Davies, CSIRO Plant Industry

Dr Furbank says about $1 million has been invested in developing the Crop Mobile Module. This is a one-of-a-kind phenotyping system made up of buggy-mounted crop monitoring technology (the Phenomobile), an airborne imaging platform (the Blimp), and a network of distributed sensors for remote monitoring of crops and the environment that uses the mobile phone network to feed data to a database that is accessible in real time through an online interface (the Phenonet). The Phenonet also provides new opportunities for real-time modelling of climate, trait and yield data.

“These systems were tested and validated at Yanco in the 2009–10 field seasons,” Dr Furbank says. “They allow non-invasive and rapid monitoring of traits previously measured using laborious and destructive techniques. Further validation and testing of new tools promise even further cost savings and higher resolution of crop performance under drought.”

IT support for the MEFs is being provided by Dr Andrzej Kilian of Diversity Arrays Technology Pty Ltd along with software tools to securely capture data produced by pre-breeders (DAR00008, 2012–14). Dr Karine Chenu at the University of Queensland has further contributed StressMaster – a decision-support tool to manage irrigation in real time and target the most representative drought patterns affecting dryland cropping (UQ00064, 2012–13).

“A functional prototype was available to MEF researchers during the 2012 growing season,” Dr Chenu says. “The tool has been fully implemented on CSIRO’s website and additional functions added for the 2013 growing season.”

Another $2 million a year is being invested in the area of gene discovery and acquisition of novel genetic resources for WUE. These projects lie further upstream in the R&D pipeline and will deliver the next generation of WUE traits for validation in MEF-based projects.

The gene discovery projects involve variation in flowering time genes (CSP00131), dwarfing genes (CSP00126), and the transpiration efficiency gene ERECTA (ANU00017). There are also projects to characterise the genetic control of root architecture (CSP00129) and of grain number during water stress (CSP00130).

“Taken together, the GRDC’s investment in the MEFs amounts to a comprehensive program to assemble a toolkit of validated traits and selection tools for breeders to produce varieties better adapted to typical water-limited conditions in all grain-growing regions in Australia,” Dr Mayer says.

“Whether selecting for roots with in-built novel water-chasing strategies or manipulating phenology patterns, researchers are being provided with the support, tools and facilities they need to fill the breeding pipeline with the traits that will better cope with the challenging and variable Australian environments.”

Upcoming issues of Ground Cover will carry in-depth coverage of individual projects as researchers reach milestones in breeding for improved WUE.

Table 1: Water-use efficiency (WUE) traits under investigation at the GRDC's managed environment facilities.
WUE trait Description GRDC project Contact information
 1. The mesophyll conductance trait
Refers to the ease with which CO2 diffuses to sites of carbon fixation within leaves.
Test whether increasing leaf mesophyll conductance increases uptake of CO2 without
increasing water loss – a combination expected to increase a crop's WUE.
Screen Australian grain varieties to determine variability in mesophyll conductance, its relevance to WUE. Material with desirable mesophyll conductance qualities will be selected for transfer to breeders. US00056 (2012-17) Led by Dr Margaret Barbour, University of Sydney, margaret.barbour@sydney.edu.au
2. The 'tin' gene.
Tin affects plant architecture by controlling tiller number to varying
extents.
Test whether variation in tin improves access to sunlight and helps conserve soil water for grain filling that otherwise is lost through excessive growth of non-productive fillers early in the season. Test the yield advantage of including the tin gene variants in commercially relevant
wheat lines under water-limited paddock
conditions.
US00052 (2010–11)
UT00024 (2012–14) 
Led by Dr Carina Moeller, University of Tasmania, carina.moeller@utas.edu.au
 3. The HST trait.
Refers to heat stress tolerance (HST).
Characterise levels of heat stress tolerance in Australian germplasm. Also study HST's impact on wheat yield and profitability. Characterise varietal responses to heat stress tolerance and identify sources of genetic variation in HST for breeders. The project also looks at published genetic QTLs associated with HST to study their impact on plant performance in a prelude to developing markers for HST.
AGP00010 (2011–13)
Led by Mr Paul Telfer, AGT, paul.telfer@ausgraintech.com
 4. The stem WSC trait and the FEH genes.
Refers to water soluble carbohydrate (WSC) accumulation in the steam and remobilisation of stored WSC to grain linked to variation in teh fructan exohydrolase (FEH) genes under water stress.
This mechanism is active in Westonia and Kauz, which have high stem WSC levels and are considered drought tolerant. Higher levels of WSC remobilisation have been noted in Westonia and result in less loss of grain weight under water deficit.  Field validate the relationship between yield, WSC remobilisation and FEH gene expression using a Kauz x Westonia double-haploid population. Use FEH genes to provide markers for drought tolerance and develop germplasm useful in producing drought tolerant wheat lines.
UMU00039 (2011–14)
Led by Dr Jingjuan Zhang, Murdoch University, j.zhang@murdoch.edu.au
 5. Validation and delivery of elite WUE traits such as:
  • longer coleoptile
  • early vigour
  • novel dwarfing genes
  • high transpiration efficiency (TE)
  • high stem WSC
  • canopy architecture
  • tiller number
  • heat stress balance
  • glaucousness
Traits that improve wheat's adaptation to drought have been developed but despite interest from breeding companies few have been adopted for commercial use because their breeding value is unclear and traits lack high-throughput, breeder-friendly, field-based phenotyping tools. Assemble relevant germplasm from across Australia and use the MEFs to validate their WUE traits. Profile the relative value of the WUE traits. Contrast and benchmark elite trait-containing lines with current commercial wheat. Develop cost-effective selection tools that facilitate trait uptake by breeding companies.
CSP00140 (2010–11)
CSP00156 (2011–14)
Led by Dr Greg Rebetzke, CSRIO Plant Industry, greg.rebetzke.csiro.au
6. Drought tolerance during crop establishment in Mediterranean climates This project is screening wheat and barley cultivars and advanced breeding lines for the ability to establish rapidly and evenly in drying seedbeds, survive early water deficit and maintain high levels of productivity. Screen germplasm using rain shelters and irrigation infrastructure at the MEF in Merredin, WA, so the data is applicable to water deficits experienced in farmers’ fields. Also doing computer simulations to identify where in Australia, how often and how severe seedbed water deficit is a production constraint and if this is likely to change in the future.
DAW00219 (2011–14)
Led by Dr Bob French, DAFWA, bob.french@agric.wa.gov.au
7. Benchmarking wheat varieties for early drought adaptations Characterise the diversity for a range of readily phenotyped drought adaptation traits in current commercial and elite breeding material under widescale yield testing in the National Variety Trials. This project also provides the baseline for all other MEF-based projects. Rank up to 160 current wheat varieties and advanced breeding lines for their ability to maintain yield under water stress.
DAW00215 (2010–14)
Led by Dr Ben Biddulph, DAFWA, ben.biddulph@agric.wa.gov.au
8. Key WUE traits in durum Durum is reputed to be suited to productive growing conditions and there is little information about key traits associated with WUE in this crop. Assess Australian durum germplasm for adaptation to drought and productivity under irrigation. Develop new selection criteria for durum breeding programs.
DAN00141 (2010–11)
DAN00162 (2011–14)
Led by Dr Gururaj Kadkol, NSW DPI, gururaj@kadkol@dpi.nsw.gov.au

More information:

Dr Jorge Mayer, GRDC,
jorge.mayer@grdc.com.au

Next: The GRDC Water Use Efficiency Initiative

Previous:Securing yields on the edge

GRDC Project Code AGP00010, ANU00017, CSP00126, CSP00129, CSP00130, CSP00131, CSP00140, CSP00148, CSP00156, DAN00141, DAN00162, DAR00008, DAW00215, DAW00219, UMU00039, UQ00064, US00056, US00052, UT00024

Region South, West, North